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  • 2020-2023
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  • 1995-1999  (183)
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  • 101
    ISSN: 1432-1084
    Keywords: Key words: Hematology ; Bone marrow ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Despite its lack of specificity, magnetic resonance imaging (MRI) of the bone marrow has the potential to play a role in the management of patients with primary neoplastic disorders of the hematopoietic system, including lymphomas, leukemias and multiple myeloma. In addition to its use in the assessment of suspected spinal cord compression, bone marrow MRI could be used as a prognostic method or as a technique to assess the response to treatment. The current review addresses the common patterns of bone marrow involvement observed in primary neoplasms of the bone marrow, basic technical principles of bone marrow MRI, and several applications of MRI in selected clinical situations.
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  • 102
    ISSN: 1432-1084
    Keywords: Key words: Bone neoplasms ; Soft tissue neoplasms ; Magnetic resonance imaging ; Osteoblastoma ; Schwannoma ; Neurilemmoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. One case of malignant schwannoma of the sacrum and another of occipital osteoblastoma were evaluated by MR imaging. Both tumors showed fluid-fluid levels with different signal intensities in the sequences performed. Pathologic examination revealed hemmorhagic fluid in both tumors. Malignant schwannoma and osteoblastoma should be included in the list of bone and soft-tissue with fluid-fluid levels. Our data confirm the non-specificity of this finding, which only suggests the presence of previous intratumoral hemorrhage.
    Type of Medium: Electronic Resource
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  • 103
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 8 (1998), S. 3-8 
    ISSN: 1432-1084
    Keywords: Key words: Rectum ; Diagnosis ; Magnetic resonance imaging ; Congenital disorders ; Inflammatory diseases ; Vascular
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The rectum has become the most successful area of the gastrointestinal tract to be studied with MRI. Its anatomical location, fixed in the pelvic fat, and its lack of peristalsis, make it an ideal organ to be scanned with MRI. In addition, MRI allows a direct sagittal and coronal display, of key importance to colorectal surgeons whose terminology and approach are based on the coronal plane. The sagittal plane allows the depiction of the relation of the rectum to the sacrum, uterus and prostate, with detail not available by other imaging techniques, and the use of endorectal coils allows excellent demonstration of the rectal wall. Although MRI has been used primarily to study rectal carcinoma, other diseases, congenital, inflammatory and vascular in origin, can be studied using the correct technique.
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  • 104
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 8 (1998), S. 116-122 
    ISSN: 1432-1084
    Keywords: Key words: Spine ; Magnetic resonance imaging ; Nerves ; spinal ; Radiculitis ; Contrast media ; paramagnetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Disc prolapse presenting with sciatica may be associated with enhancement of the symptomatic nerve root following magnetic resonance imaging (MRI) with intravenous gadolinium (Gd)-DTPA. Previous studies have shown, however, that this does not occur in all cases. The aim of this study was to assess the incidence of nerve root enhancement in patients with sciatica and disc prolapse and to try to identify any specific features that might be associated with the phenomenon. A total of 227 patients presenting with low back pain and/or sciatica underwent a MRI study of the lumbar spine with intravenous contrast enhancement. Nineteen of 81 (23.5 %) patients with disc prolapse demonstrated nerve root enhancement. Nerve root enhancement had a highly significant association with sequestrated disc lesions (13/19, 68 %; P 〈 0.0005), and was primarily seen in the symptomatic ipsilateral nerve root (16/19, 84 %). The sensitivity of nerve root enhancement associated with disc prolapse was 23.5 % with a specificity of 95.9 %, a positive predictive value of 76 % and a negative predictive value of 69.3 %. Nerve root enhancement may be indicative of the symptomatic level but its poor sensitivity negates the routine use of Gd-DTPA in MRI for sciatica.
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  • 105
    ISSN: 1432-1084
    Keywords: Key words: Rhabdomyosarcoma ; Magnetic resonance imaging ; Larynx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We report a rare case of a young girl with an embryonal rhabdomyosarcoma of the right aryepiglottic fold. Local disease recurrence, occurring 7 years after subtotal resection and adjuvant chemotherapy, was studied with plain radiography, CT and MRI. To the best of our knowledge, this is the first report illustrating the MRI characteristics of a laryngeal embryonal rhabdomyosarcoma in a child.
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  • 106
    Electronic Resource
    Electronic Resource
    Springer
    European spine journal 7 (1998), S. 344-347 
    ISSN: 1432-0932
    Keywords: Key words Lipoma ; Computed tomography ; Magnetic resonance imaging ; Radiography ; Vertebral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Osseous lipomata of vertebral bodies are rare. We present a very unusual case where adjacent vertebrae are involved and the plain radiographic and scintigraphic appearances gave cause for some concern. The findings on plain films, scintigraphy, computed tomography and magnetic resonance imaging are discussed.
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  • 107
    ISSN: 1432-1459
    Keywords: Key words Vascular dementia ; Dominant inheritance ; Cognition ; Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a 2-year prospective neuropsychological study of five asymptomatic subjects with magnetic resonance imaging (MRI) abnormalities from an Italian kindred affected by cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). These subjects completed tests for attention capacities, processing speed, abstract thinking, short-term memory, learning and constructional praxis. Seven normal subjects matched for age and education, belonging to the same pedigree and not having MRI hyperintensities were examined as controls. The results did not show significant differences between asymptomatic subjects and normal controls. Cognitive performance of asymptomatic subjects did not deteriorate during a 2-year follow-up. Our findings suggest that, at this stage of the disease process, the presence of diffuse leukoencephalopathy does not imply subtle cognitive defects.
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  • 108
    ISSN: 1432-1459
    Keywords: Key words Alzheimer dementia ; Magnetic resonance imaging ; Temporal lobe ; Amygdala ; High ; signal lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to assess selective atrophy of the temporal lobe and amygdala in the early stages of Alzheimer dementia (AD). Magnetic resonance imaging (MRI) measurements and the presence of highsignal lesions (HSL) were analysed in 31 patients with mild to moderate probable AD and 22 controls. In the AD group, MRI findings were compared with cognitive variables and specific features of memory functions. Alzheimer patients showed a significant reduction in volumetric measurement compared with controls in the total volume (P 〈 0.01), temporal lobe (P 〈 0.01) and amygdala (P 〈 0.05). The temporal lobe/brain volume ratio was also significantly reduced in AD subjects (P 〈 0.05). Atrophy of temporal structures was significantly related to the degree of episodic and semantic memory impairment according to a material-specific effect. No significant correlations between amygdala and cognitive variables were found. The results of our study confirm the usefulness of measures of temporal lobe atrophy assessed with MRI in the diagnosis of AD. In contrast, HSL are relatively common in AD patients (12/31 cases) and were not related to volumetric findings, severity of dementia or functional disability.
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  • 109
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 262 (1998), S. 91-94 
    ISSN: 1432-0711
    Keywords: Key words: Placenta accreta ; Uterine abscess ; Magnetic resonance imaging ; CT scan ; Ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The postpartum magnetic resonance imaging (MRI) appearance of a patient with placenta accreta and abscess formation is presented here and compared to the ultrasound and CT findings. The diagnosis was confirmed on histopathologic examination and cultures of the hysterectomy specimen. On MRI, the T1-weighted acquisitions showed an enlarged uterus of mildly heterogeneous but predominantly low signal intensity. The T2-weighted images demonstrated a heterogenous area of predominantly bright signal within the uterine body and fundus. In this case, MRI was more informative than ultrasound and non-contrast CT scan in the postpartum diagnosis of placenta accreta with abscess formation.
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  • 110
    Electronic Resource
    Electronic Resource
    Springer
    Child's nervous system 14 (1998), S. 537-546 
    ISSN: 1433-0350
    Keywords: Key words Fourth ventricle ; Brain stem ; Cerebellum ; Astrocytoma ; Brain neoplasms ; Craniotomy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The authors conducted a study of 21 children with benign astrocytomas in the IV ventricle treated with radical tumor resection from 1982 through 1991. The purposes of this study were to identify the tumor origin and neural involvement, and to determine the natural history following surgical resection. Pathological studies showed that 18 were pilocytic astrocytomas (pure pilocytic in 12, mixed in 6), 2 fibrillary, and 1 gemistocytic. In the IV ventricle, 12 patients had a transependymal involvement of the floor (brain stem), 6 had an involvement of the wall (cerebellar peduncle), and 3 had involvement of both floor and wall. A gross total resection was performed in 9 patients, and the remaining 12 patients underwent a subtotal resection. All patients were followed without radiation therapy (RT) or chemotherapy. During a follow-up period of 6.5–15 years, all patients were alive. Eight patients suffered recurrence between five months and 66 months after diagnosis. Of these, five received RT for recurrence and had a complete response in all cases. The remaining 13 patients showed no evidence of disease and one had a stable residual tumor. The recurrence-free 5-year and 10-year survival rates were 62.5% and 57% respectively. Patients without brainstem involvement, with total resection, or with pure pilocytic astrocytoma had a better outcome than those with brain stem involvement, with subtotal resection, or with nonpilocytic or mixed histology. In summary, a great majority of benign IV ventricle astrocytomas involve the floor of the IV ventricle. It is often difficult to determine the origin of these tumors in most cases. Benign IV ventricle astrocytomas may not recur even after incomplete resection, and close observation without RT is recommended, although RT appears to be effective for these tumors when they recur.
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  • 111
    Electronic Resource
    Electronic Resource
    Springer
    Child's nervous system 14 (1998), S. 135-138 
    ISSN: 1433-0350
    Keywords: Key words Hallervorden-Spatz syndrome ; Optic atrophy ; Basal ganglia ; Iron deposits ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 16-year-old boy with the classic or postinfantile type of Hallervorden-Spatz syndrome is described. Bilateral optic atrophy with visual loss but without retinal changes was the only presenting symptom. Mild cognitive impairment, behavioural disturbances and insidious extrapyramidal involvement appeared later. MRI showed marked symmetrical hypointensity of the globi pallidi and substantia nigra. This new observation suggests that the occurrence of optic atrophy in a patient with Hallervorden-Spatz syndrome should be regarded as noncoincidental and stresses the importance of an accurate neurological work-up in all adolescents with any unusual form of progressive optic atrophy.
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  • 112
    ISSN: 1432-2161
    Keywords: Key words Slipped capital femoral epiphysis ; Physis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To define and compare early lesions associated with slipped capital femoral epiphysis (SCFE) on magnetic resonance imaging (MRI), computed tomography (CT) and radiography. Design and patients. Thirteen patients with 15 symptomatic hips due to SCFE underwent radiography and MRI; CT was performed in 12 patients. SCFE was graded on radiographs, head/neck angles and qualitative changes were evaluated on CT, and morphologic/signal abnormalities were determined on MRI. Results. Physeal widening, apparent on T1-weighted MRI, was evident in every case of SCFE, including one presumed “pre-slip.” T2-weighted images demonstrated synovitis and marrow edema but obscured physeal abnormalities. CT head/neck angles ranged from 4–57° for symptomatic to 0–14° for asymptomatic hips. Physeal and metaphyseal changes were variably identified on both radiographs and CT in all cases of SCFE, but not in the pre-slip. Conclusion. MRI clearly delineates physeal changes of both pre-slip and SCFE, and demonstrates very early changes at a time when radiographs and CT may appear normal.
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  • 113
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 27 (1998), S. 161-163 
    ISSN: 1432-2161
    Keywords: Key words Parosteal osteoma ; Iliac bone ; Computed tomography ; Magnetic resonance imaging ; Partial regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A 33-year-old patient with a 2-year history of intermittent pain in the right gluteal region and thigh presented with a large sclerotic lesion of the iliac bone. From the findings on radiography, scintigraphy, CT and MRI, a giant parosteal osteoma was suspected. The histological examination confirmed the diagnosis. Since the lesion was extensive it was observed with periodic follow-up examinations. At present, 5 years after the diagnosis, the patient is asymptomatic and imaging studies show that the lesion persists with reduction of sclerosis and size. The tumor was on the surface as well as intramedullary – only one other case with such a distribution is known to us – and it was also in the iliac bone.
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  • 114
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 27 (1998), S. 266-270 
    ISSN: 1432-2161
    Keywords: Key words Granuloma annulare ; Magnetic resonance imaging ; Soft-tissue tumors ; Rheumatoid nodule ; Pseudo-rheumatoid nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. Granuloma annulare is an uncommon benign inflammatory dermatosis characterized by the formation of dermal papules with a tendency to form rings. There are several clinically distinct forms. The subcutaneous form is the most frequently encountered by radiologists, with the lesion presenting as a superficial mass. There are only a few scattered reports of the imaging appearance of this entity in the literature. We report the radiologic appearance of five cases of subcutaneous granuloma annulare. Design and patients. The radiologic images of five patients (three male, two female) with subcutaneous granuloma annulare were retrospectively studied. Mean patient age was 6.4 years (range, 2–13 years). The lesions occurred in the lower leg (two), foot, forearm, and hand. MR images were available for all lesions, gadolinium-enhanced imaging in three cases, radiographs in four, and bone scintigraphy in one. Results. Radiographs showed unmineralized nodular masses localized to the subcutaneous adipose tissue. The size range, in greatest dimension on imaging studies, was 1–4 cm. MR images show a mass with relatively decreased signal intensity on all pulse sequences, with variable but generally relatively well defined margins. There was extensive diffuse enhancement following gadolinium administration. Conclusion. The radiologic appearance of subcutaneous granuloma annulare is characteristic, typically demonstrating a nodular soft-tissue mass involving the subcutaneous adipose tissue. MR images show a mass with relatively decreased signal intensity on all pulse sequences and variable but generally well defined margins. There is extensive diffuse enhancement following gadolinium administration. Radiographs show a soft-tissue mass or soft-tissue swelling without evidence of bone involvement or mineralization. This radiologic appearance in a young individual is highly suggestive of subcutaneous granuloma annulare.
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  • 115
    ISSN: 1432-2161
    Keywords: Key words Joints ; Knee joints ; Cartilage ; Magnetic resonance imaging ; Susceptibility effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective: To study magnetic resonance (MR) imaging pattern of normal hyaline articular cartilage in the knee joint with regard to the contribution of the “magic angle” effect to the MR signal. Design. Thirty-two healthy volunteers were imaged in a standard supine position in a 1.5-T unit using spin echo and gradient echo sequences. Nine volunteers were reimaged with the knee flexed. The signal behavior of the hyaline cartilage of the femoral condyles was evaluated qualitatively and quantitatively. The extended and flexed positions of the nine volunteers were compared. Results. A superficial and a deep hyperintense layer and a hypointense middle cartilage layer were observed. Segments of increased signal intensity were visible along the condyles; a magic angle effect on signal intensity was evident in the hypointense middle layer with both gradient echo and spin echo images. Conclusion. The MR signal behavior of hyaline cartilage is influenced by the alignment of the collagen fibers within the cartilage in relation to the magnetic field. Failure to recognize this effect may lead to inaccurate diagnosis.
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  • 116
    Electronic Resource
    Electronic Resource
    Springer
    Child's nervous system 14 (1998), S. 139-141 
    ISSN: 1433-0350
    Keywords: Key words Cerebellitis ; Hydrocephalus ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 14-year-old boy presented acutely with occipital headache, nausea and vomiting. MRI showed obstructive hydrocephalus and marked bilateral cerebellar swelling with increased signal on T2-weighted imaging. Following treatment with oral corticosteroids, the clinical and radiological signs resolved. The clinical course and radiological appearances were consistent with cerebellitis associated with a significant mass effect and hydrocephalus.
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  • 117
    ISSN: 1433-0350
    Keywords: Key words Diffuse astrocytoma ; Bilateral thalamic astrocytomas ; Computed tomography ; Magnetic resonance imaging ; Hyperfractionated radiotherapy ; Chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the case of a 13-year-old girl with diffuse bilateral thalamic astrocytomas. Incoordination was observed at the onset. Cranial computed tomography (CT) showed enlarged thalami, and magnetic resonance imaging (MRI) revealed these lesions to be symmetrically enlarged with high intensity on the T2-weighted image. Owing to these atypical findings in the neuroimaging studies, we had difficulty in making the correct diagnosis of a brain tumor. After the diagnosis of diffuse bilateral thalamic astrocytomas was obtained, we performed hyperfractionated radiotherapy followed by chemotherapy. Radiation therapy was effective for a while, but the girl's condition deteriorated again and she died 8 months after admission. Although diffuse bilateral thalamic astrocytomas are difficult to diagnose because they do not resemble most other neoplasms on neuroimaging studies, pediatricians should keep this entity in mind in order to arrive at a precise and prompt diagnosis.
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  • 118
    ISSN: 1433-0350
    Keywords: Key words Choroid plexus cyst ; Lateral ventricle ; Intraventricular cyst ; Magnetic resonance imaging ; CT-stereoendoscopy ; Diomed 25 laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A cyst of the choroid plexus of the left lateral ventricle with intermittent blockage of the foramen of Monro and initially with invagination of the III ventricle in a child is described. In a 6-week-old boy a ventriculoatrial shunt was implanted for correction of an active asymmetrical hydrocephalus of unknown origin. When he was 3 months of age a water-soluble contrast CT ventriculography revealed a noncolloid cyst localised predominantly in the upper portion of the III ventricle. At that time the ventricular catheter obstructed with choroid plexus was removed; new bilateral catheters in a parieto-occipital region were implanted. In the course of the next 4 years, first the atrial catheter had to be extracted and then the peritoneal catheter was changed, in both cases because of obstruction. Periods of normal life alternated with periods of transient and intermittent symptoms of increased intracranial pressure, papilloedema, and myoclonic jerks. Repeated computed tomography (CT) and magnetic resonance imaging (MRI) showed stabilised hydrocephalus with an enlarged left lateral ventricle. When the boy was 16 years old MRI revealed a choroid plexus cyst in the left lateral ventricle 2 cm in diameter, with a ball-valve type of obstruction of the foramen of Monro. CT stereoendoscopic resection of the wall of a large cyst filled with cerebrospinal fluid was performed, and two additional adnexal small cysts were coagulated using the bipolar coagulator, Diomed 25 laser and scissors; the symptoms then regressed, except for superior bilateral altitudinal anopsia. Light and electron microscopy of the cyst wall is reported. The cyst was composed of collagenic connective tissue lined with a basal lamina lacking in epithelial cells. The preoperative and postoperative MRI are presented. Choroid plexus cysts localised in the anterior part of lateral ventricles are very rare, and all reported cases have been in male patients. According to the literature our case is only the third ever described in a child.
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  • 119
    Electronic Resource
    Electronic Resource
    Springer
    Child's nervous system 14 (1998), S. 747-750 
    ISSN: 1433-0350
    Keywords: Key wordsListeria monocytogenes ; Magnetic resonance imaging ; Intracerebral cyst ; Neonatal ; Pregnancy complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present the rare case of a girl surviving intrauterine listeria brain stem meningoencephalitis, who subsequently developed hydrocephalus, a trapped IV ventricle and an intramedullary cyst. Such cases have been reported only infrequently, and in earlier cases modern imaging studies were not available. Magnetic resonance imaging has been helpful in our patient to delineate the lesions and plan further treatment.
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  • 120
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Maligne Gliome ; Hirnödem ; Rezidiv ; Magnetresonanztomographie ; Key words Malignant glioma ; Brain edema ; Tumor recurrence ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose: To assess the influence of initial preoperative brain edema in malignant gliomas on regrowth patterns. Subjects and methods: 79 patients with histologically verified supratentorial malignant glioma were prospectively studied by magnetic resonance imaging (MRI) before and every 2–3 months after surgery. The median follow-up time was 11 months. We correlated the configuration of the initial vasogenic edema on T2-weighted images with tumor regrowth patterns on contrast-enhanced T1-weighted images. Results: 35/47 tumor regrowths (75%) imitated the initial edema configuration, while 11/47 occurred within the initial tumor bed; in one case tumor recurrence was multilocal. Conclusion: In glioblastoma, tumor regrowth patterns correlate positively with the configuration of the initial vasogenic brain edema. The initial, „presurgical” peritumoral edema should thus be considered when planning further treatment.
    Notes: Zusammenfassung Fragestellung: Beeinflussen Form und Größe des präoperativen peritumoralen Hirnödems die Rezidiventwicklung bei malignen supratentoriellen Gliomen? Methodik: Prospektiv wurden 79 Patienten mit einem malignen supratentoriellen Gliom mit einem standardisierten MRT-Protokoll untersucht. MRT-Untersuchungen erfolgten vor der neurochirurgischen Operation, möglichst innerhalb der ersten 3 Tage nach Operation und während der Nachbeobachtungszeit in Abständen von 2–3 Monaten. Die mediane Nachbeobachtungszeit betrug 11 Monate. Die initiale präoperative Ödemkonfiguration auf den T2-gewichteten MRT-Aufnahmen wurde mit der Rezidivtumorkonfiguration auf den Kontrastmittel verstärkten T1-gewichteten Aufnahmen verglichen. Ergebnisse: 47 Patienten entwickelten während der Nachbeobachtungszeit ein Rezidiv. Die Konfiguration des Rezidivtumors imitierte in 35/47 Patienten (75%) die initiale präoperative Ödemkonfiguration. Bei 11/47 Patienten entwickelte sich ein lokales und bei einem Patienten ein multilokales Rezidiv. Schlußfolgerungen: Die präoperative Tumorödemkonfiguration im T2-gewichteten MRT-Bild korreliert mit der Rezidivtumorausdehnung. Zukünftige Therapiestudien sollten daher die Ausdehnung des initalen präoperativen Ödems als zusätzlichen prognostischen Faktor mitberücksichigen.
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  • 121
    ISSN: 1433-8491
    Keywords: Key words. Bipolar affective disorder ; Phosphorus-31 magnetic resonance spectroscopy ; Magnetic resonance imaging ; Mood disorder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The authors have previously reported decreased intracellular pH (pHi) in the frontal lobes in euthymic bipolar patients treated with lithium using 31P-MRS. White matter hyperintensity (WMHI) is frequently seen in bipolar disorder. To examine a possible effect of lithium on pHi and the relationship between pHi and WMHI, seven drug-free euthymic bipolar patients were examined, and T2-weighted MRI were examined in 14 previously reported bipolar patients. Drug-free patients showed significantly lower pHi than controls. WMHI was associated with low pHi and increased phosphodiester peak. These results suggest that decrease of pHi is not an effect of lithium but is instead related to the pathophysiology of illness. Decrease of pHi and increase of the PDE peak may be the biochemical basis of WMHI in bipolar disorder.
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  • 122
    ISSN: 1615-3146
    Keywords: Epiphysenlösung ; Epiphysiolysis capitis femoris ; Hüftkopf ; Kernspintomographie ; Hüfte ; Röntgendiagnostik ; Slipped epiphysis ; Femur head ; Magnetic resonance imaging ; Hip radiography ; Technology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Diagnosis and determination of severity of chronic slipped capital femoral epiphysis (SCFE) is usually made from clinical history, physical examination and radiographic measurement of the degree of slippage. Aim of the present study is to evaluate the diagnostic impact of magnetic resonance imaging in early detection of SCFE. We evaluated magnetic resonance imaging of the hips of 5 healthy children in comparison to the findings in conventional radiographs and magnetic resonance imaging of 9 patients with suspected SCFE. The growth plate of healthy objects shows homogenous low signal intensity, constant width up to 3 mm, and is clearly defined against the surrounding osseous structures. The adjacent surface appears homogenous. Patients with suspected SCFE showed widened growth plate (〉 3 mm) in 6 of 9 cases. Articular effusion was seen in all cases of clinical suspected disease. Incongruence of the ondulate surfaces was seen. Here we found flattening of denticulation of the growth plate in addition. Growth plate showed increase of signal intensity in 2 cases.
    Notes: Zusammenfassung Die Diagnose der im Jugendalter spontan auftretenden Epiphysiolysis capitis femoris wurde bislang anhand der klinischen Beschwerden sowie der Bestimmung des Abrutschwinkels in konventionellen Aufnahmen (Beckenübersicht, Aufnahme nach Rippstein) gestellt. Für die Diagnose der Frühformen der Epiphysiolysis capitis femoris exsistiert kein allseits akzeptierter Goldstandard. Ziel der vorliegenden Arbeit war es herauszuarbeiten, inwieweit die Epiphysiolysis capitis femoris charakteristische Zeichen in der Kernspintomographie bietet und ob die MRT in der Lage ist, früher Veränderungen als die konventionellen Methoden zu erkennen. Die Kernspintomographien (1,5-T-, T1- und T2-SE-Sequenzen koronar, sagittal, paraaxial, fakultativ STIR-, TIRM-, FLASH-2D-Sequenzen) von fünf gesunden Kindern wurden standardisiert analysiert und mit den magnetresonanztomographischen Untersuchungen von neun Patienten mit vermuteter Epiphysiolysis capitis femoris verglichen. Bei den neun Patienten lagen zusätzlich konventionelle Röntgenaufnahmen nach Rippstein vor. Im Normalkollektiv stellte sich die Epiphysenfuge homogen signalarm bzw. signalfrei dar. Sie wies eine konstante Weite bis zu 3 mm auf und war gegenüber den angrenzenden knöchernen Strukturen scharf abgegrenzt. Das Grenzflächensignal erschien homogen und gezähnelt. Patienten mit vermuteter Epiphysiolysis capitis femoris zeigten eine Erweiterung der Epiphysenfuge auf mehr als 3 mm in sechs von neun Fällen. Bei allen klinisch verdächtigen Fällen konnte ein Gelenkerguß abgegrenzt werden. Es fand sich zusätzlich eine Verschiebung oder Abflachung der Verzähnelung. Ein Signalanstieg im Bereich des Knorpels fand sich kernspintomographisch in nur zwei Fällen.
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  • 123
    ISSN: 1619-7089
    Keywords: Key words: Absorbed Dose ; S-value ; MIRD phantom ; Whole-body positron emission tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this study was to measure the cumulated activity and absorbed dose in organs after intravenous administration of 2-[F-18]fluoro-2-deoxy-d-glucose (18F-FDG) using whole-body positron emission tomography (PET) and magnetic resonance imaging (MRI). Whole-body dynamic emission scans for 18F-FDG were performed in six normal volunteers after transmission scans. The total activity of a source organ was obtained from the activity concentration of the organ measured by whole-body PET and the volume of that organ measured by whole-body T1-weighted MRI. The cumulated activity of each source organ was calculated from the time-activity curve. Absorbed doses to the individuals were estimated by the MIRD (medical internal radiation dosimetry) method using S-values adjusted to the individuals. Another calculation of cumulated activities and absorbed doses was performed using the organ volumes from the MIRD phantom and the ”Japanese reference man” to investigate the discrepancy of actual individual results against the phantom results. The cumulated activities of 18 source organs were calculated, and absorbed doses of 27 target organs estimated. Among the target organs, bladder wall, brain and kidney received the highest doses for the above three sets of organ volumes. Using measured individual organ volumes, the average absorbed doses for those organs were found to be 3.1×10–1, 3.7×10–2 and 2.8×10–2 mGy/MBq, respectively. The mean effective doses in this study for individuals of average body weight (64.5 kg) and the MIRD phantom of 70 kg were the same, i.e. 2.9×10–2 mSv/MBq, while for the Japanese reference man of 60 kg the effective dose was 2.1×10–2 mSv/MBq. The results for measured organ volumes derived from MRI were comparable to those obtained for organ volumes from the MIRD phantom. Although this study considered 18F-FDG, combined use of whole-body PET and MRI might be quite effective for improving the accuracy of estimations of the cumulated activity and absorbed dose of positron-labelled radiopharmaceuticals.
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  • 124
    ISSN: 1619-7089
    Keywords: Key words: Ictal single-photon emission tomography ; Positron emission tomography ; Magnetic resonance imaging ; EEG-video monitoring ; Epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Although ictal single-photon emission tomography (SPET) with technetium-99m ethyl cysteinate dimer (ECD) has a well-established role in the diagnostic evaluation of patients with temporal lobe epilepsy who are being considered for epilepsy surgery, its use in cases of extratemporal epilepsy is still limited. We investigated the influence of the propagation of extratemporal epileptic seizure activity on the regional increase in cerebral blood flow, which is usually associated with epileptic seizure activity. Forty-two consecutive patients with extratemporal epilepsies were prospectively evaluated. All patients underwent ictal SPET studies with simultaneous electroencephalography (EEG) and video recordings of habitual seizures and imaging studies including cranial magnetic resonance imaging and positron emission tomography with 2-[18F]-fluoro-2 deoxy-d-glucose. Propagation of epilptic seizure activity (PESA) was defined as the absence of hyperperfusion on ictal ECD SPET in the lobe of seizure onset, but its presence in another ipsilateral or contralateral lobe. Observers analysing the SPET images were not informed of the other results. PESA was observed in 8 of the 42 patients (19%) and was ipsilateral to the seizure onset in five (63%) of these eight patients. The time between clinical seizure onset and injection of the ECD tracer ranged from 14 to 61 s (mean 34 s). Seven patients (88%) with PESA had parieto-occipital epilepsy and one patient had a frontal epilepsy. PESA was statistically more frequent in patients with parieto-occipital lobe epilepsies (58%) than in the remaining extratemporal epilepsy syndromes (3%) (P〈0.0002). These findings indicate that ictal SPET studies require simultaneous EEG-video recordings in patients with extratemporal epilepsies. PESA should be considered when interpreting ictal SPET studies in these patients. Patients with PESA are more likely to have parieto-occipital lobe epilepsy than seizure onset in other extratemporal regions.
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  • 125
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    European archives of oto-rhino-laryngology and head & neck 255 (1998), S. 18-21 
    ISSN: 1434-4726
    Keywords: Key words Parotid gland ; Solitary fibrous tumor ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Solitary fibrous tumors (SFT) arise in the pleura and less commonly in extrapleural sites. Head and neck regions have included the nose and paranasal sinuses, soft palate, epiglottis, thyroid, parotid and submandibular glands, as well as the infratemporal fossa and parapharyngeal space. We report a case of SFT arising from the parotid gland and extending to the parapharyngeal space. To our knowledge, this is the fourth case of SFT originating from the parotid gland and is the largest of its kind among the extrapleural lesions described. The characteristics revealed by computed tomography and magnetic resonance imaging are presented.
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  • 126
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    Clinical rheumatology 17 (1998), S. 166-169 
    ISSN: 1434-9949
    Keywords: Magnetic resonance imaging ; Tenosynovitis ; Tuberculosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A patient with tenosynovial tuberculosis affecting the extensor tendons of the wrist and hand is presented. This case highlights the clinical and magnetic resonance features of tuberculous tenosynovitis, and seeks to increase awareness of what may represent a resurgent musculoskeletal entity.
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  • 127
    ISSN: 1434-9949
    Keywords: Gadolinium ; Magnetic resonance imaging ; Radiosynovectomy ; Rheumatoid arthritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The intra-articular injection of a radiopharmaceutical agent (radiosynovectomy) produces a reduction of the synovial inflammatory process. The inflammed synovial membrane can be identified with magnetic resonance imaging after the intravenous administration of gadolinium (MRI-Gd). A 6-month prospective study was carried out in 10 patients with rheumatoid arthritis after radiosynovectomy of the knee. The efficacy was evaluated with clinical parameters and MRI-Gd. A progressive amelioration of synovial effusion, pain, articular range of mobility, total leucocytes count in synovial fluid and synovial membrane thickness through MRI-Gd was observed. The global efficacy was considered to be good in six patients, fair in three and bad in one. The study shows for the first time that MRI-Gd allows the evaluation of the response of the synovial membrane to radiosynovectomy.
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  • 128
    ISSN: 1435-0130
    Keywords: Key words Velopharyngeal insufficiency ; Magnetic resonance imaging ; Velopharyngeal pathophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The disadvantages and limitations of imaging methods to investigate velopharyngeal incompetence have created some difficulties in the management of this condition. Seven normal volunteers and seven patients who were suffering from a speech disorder were examined using magnetic resonance imaging. The velopharyngeal aperture was evaluated at rest and during phonation. In normal volunteers, the velopharyngeal aperture area had a mean value of 1.632 cm2 while at rest and complete closure was obtained during the phonation of /s/ sound. Detailed information was obtained about the function of the levator palati muscle. In five patients during the phonation of /s/ sound there was an increase in the area of the velopharyngeal aperture when compared to the volunteers. Investigation with magnetic resonance imaging is helpful in the pretreatment evaluation and postopertive follow-up examination of velopharyngeal insufficiency. As a result, this noninvasive method can be used as an alternative to conventional radiological investigations.
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  • 129
    ISSN: 1590-3478
    Keywords: Cavernoma ; Intramedullary cavernous angioma ; Magnetic resonance imaging ; Transthoracic approach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intramedullary cavernous angiomas are rare vascular malformations; all published cases have been surgically approached posteriorly by standard laminectomy. We describe the case of a 63-year-old man with an intramedullary cavernous angioma, anteriorly located in the thoracic spinal cord. The angioma was operated on by transthoracic approach and totally removed.
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  • 130
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    Neurological sciences 19 (1998), S. S399 
    ISSN: 1590-3478
    Keywords: Multiple sclerosis ; Magnetic resonance imaging ; Cognitive functions ; Magnetization transfer imaging Frontal lobe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario In questa revisione della letteratura, vengono presentati e discussi i risultati di recenti studi di risonanza magnetica (RM) quantitativa nei quali il grado di deficit cognitivo in pazienti affetti da sclerosi multipla e stato correlato con l'estensione e la gravity delle alterazioni encefaliche evidenziate con tecniche differenti di RM, al fine di raggiungere una migliore comprensione dei meccanismi patogenetici sottesi allo sviluppo di tall deficit.
    Notes: Abstract In this review, the results of recent quantitative magnetic resonance imaging (MRI) studies correlating the degree of cognitive impairment in multiple sclerosis patients with the extent and severity of brain abnormalities seen using MRI techniques are presented and discussed with the ultimate goal of a better understanding of the pathophysiological mechanisms underlying the development of such deficits.
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  • 131
    ISSN: 1590-3478
    Keywords: Azygous anterior cerebral artery ; Cerebral infarction ; Digital subtraction angiography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe the unusual case of a 63-year-old woman with a history of arterial hypertension who presented a sudden weakness of the lower limbs followed by mutism, akinesia and dyspraxia. Magnetic resonance images showed a bilateral medial frontal infarction. Digital subtraction angiography documented a right azygous anterior cerebral artery with severe stenosis in its sub-callosal tract; the left anterior cerebral artery showed mild hypoplasia with only sub-frontal and fronto-polar branches. No embolic source was documented. Afterwards the patient presented a gradual and partial recovery of both motor and cognitive functions.
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  • 132
    ISSN: 1573-9686
    Keywords: Heart ; Magnetic resonance imaging ; Cardiovascular models ; Right ventricular function ; Ventricular contractile motion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract As the importance of the right ventricle in many diseases and conditions has been realized, the need for quantitative assessment of the motion and contraction of the right ventricular free wall (RVFW) has become apparent. This study applied the myocardial tagging magnetic resonance imaging (MRI) technique to the normal RVFW to elucidate normal heterogeneity in RV motion and contractile patterns. The RVFW was divided into three segments (inferior, mid and superior) in each of three slices (apical, mid and basal) to allow for a detailed analysis of the motion and contraction. Percent segmental shortening (PSS) was used to measure the amount of contraction, and a vector analysis was used to quantitate the trajectory of the RVFW through systole. PSS increased monotonically through time to an average across all segments of 12% in the basal slice, 14% in the mid-ventricular slice, and 16% in the apical slice of the heart. The trajectory of the RVFW was characterized by a wave of motion toward the septum and outflow tract. The data provided in this study provide a better understanding of normal RV kinematics and can serve as a comparison for disease states. © 1998 Biomedical Engineering Society. PAC98: 8759Pw, 0705Pj, 8745Dr
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    Annals of biomedical engineering 26 (1998), S. 557-566 
    ISSN: 1573-9686
    Keywords: Shear stress ; Blood velocity ; Kinetic energy ; Pulmonary artery flow ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In this study, an application was developed to measure three-dimensional blood flow in the main, right, and left pulmonary arteries of seven healthy volunteers using phase contrast magnetic resonance imaging (MRI). Presently, no other noninvasive technique is capable of providing this information. Flow, mean velocity, kinetic energy, and cross-sectional area were measured at multiple phases of the cardiac cycle and were consistent with previously reported values measured with one-dimensional velocity encoded MRI and Doppler echocardiography. Additionally, axial, circumferential, and radial shear stresses near the wall of the vessel at multiple phases of the cardiac cycle were estimated using the in-plane velocities. All three shear stresses were relatively constant along the vessel wall and throughout the cardiac cycle (∼ 7 dyn/cm2). This three-dimensional characterization of normal pulmonary blood flow provides a base line to which effects of altered pulmonary artery flow patterns in disease can be compared. [Morgan, V. L., T. P. Graham, Jr., and C. H. Lorenz. Circulation Suppl. 94:I–417 (abstract), 1996]. © 1998 Biomedical Engineering Society. PAC98: 8759Pw, 8745Hw
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  • 134
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    Process Safety Progress 17 (1998), S. 61-67 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Risk assessments have been performed to determine the risk associated with the transportation of hazardous wastes through a city. In the course of these assessments, a number of modeling issues arose relating to transportation accident rates, the characterization of incidents, the effect of thermal radiation, the impact of exposure to toxic chemicals, and the threshold for acceptable risk. This paper discusses these issues.
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  • 135
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    Process Safety Progress 17 (1998), S. S3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 136
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    Process Safety Progress 17 (1998), S. 98-103 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents the design of ribbon wound pressure vessels useful for Ammonia, Urea and Methanol plants. The design is to create a thin shell of 1/5 the total wall thickness required, weld it to the end pieces, and wind 4 to 8 mm thick ribbons of 80 mm width at an angle of 15 to 30 degrees on the inner shell, using a prestress. The ribbons are welded at the ends and an even number of layers are wound cross-helically on to the shell. With more than 7000 vessels over the pressure range of 50 to 350 atmospheres in use in the various chemical industries in China over the past 30 years, their safety record has been excellent. Of particular interest has been the application of this technology in the Ammonia and Urea plants, where the design allows fabrication of these vessels at substantial reduction in cost, and early delivery, when compared to the mono wall technology.
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  • 137
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    Process Safety Progress 17 (1998), S. 20-22 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most audits try to look at a representative selection of the plant procedures and equipment. An alternative is a survey, a look in depth at selected procedures (such as those for testing alarms and trips, issuing permits-to-work, controlling modifications, taking samples or testing relief devices) or selected equipment (such as level glasses or equipment for handling LPG). If the procedure or equipment is well-chosen, surveys may make a bigger contribution to safety, per person-hour, than a conventional audit.
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  • 138
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    Process Safety Progress 17 (1998), S. 39-42 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Under OSHA 1910.119, all Process Safety Management (PSM) facilities are required to keep their pressure relief system design information current. This article demonstrates why a pressure relief system design verification effort must be based on an equipment list, rather than a relief device list, in order to ensure that every piece of equipment is adequately protected. The formerly common practice of simply checking the design bases of all existing relief devices is deficient is deficient since this technique does not systematically ensure that every piece of equipment is protected.The “Berwanger Method” is a step by step process for designing or analyzing a pressure relief system to meet OSHA 1910.119 Process Safety Information (PSI) and Process Hazard Analysis (PHA) mandates. The method uses a relational database which tracks the relationships between protected equipment, potential overpressure scenarios, and protective devices.The challenge facing an operating company does not end once the design basis has been “verified” - the design basis information must also be maintained and be readily accessible to avoid costly reinvention of the wheel down the road. The “Berwanger Method” also addresses these maintenance issues.
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  • 139
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    Process Safety Progress 17 (1998), S. 49-60 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper reports on a comprehensive literature search and small scale experimental work on the reaction characteristics of phosphorous trichloride and water. More than 30 tests were conducted, including both closed and open test cells. The water to phosphorus trichloride molar ratio was varied from 1 to 25. When in contact, water and phosphorus trichloride will form two liquid layers with a reaction starting at the interface. The impact of variables on reaction rates including the interface surface area, layer depth, and stirring were investigated experimentally. A reaction rate model that fits all the measured data is presented. Case studies illustrating the use of this data for emergency relief systems and vent containment design are presented in reference. [1].
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  • 140
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    Process Safety Progress 17 (1998), S. 68-73 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two major accidents in the 80's: the summit Tunnel Fire, England and Piper Alpha disaster, an offshore platform in the North Sea; and very recently, possible explosion of the Boeing, TWA flight 800 at New York, makes it imperative that further research into the mechonisms of the ignition of flammable vapor/air mixture in contact with hot surfaces needs to be done. There have been a number of studies of ignition by hot surfaces, but in all these studies the ignition sources were wire, sphere or strip, i.e., most of them were flat surfaces. But to the authors' knowledge, other variables which affect the ignition mechanism such as irregular geometrical shapes have not been studied. The purpose of this paper is to examine how the degree of confinement (or, configuration), size and orientation, of the heated surface affects the ignition temperature of the flammable vapors. The results were obtained by experimentnal and by computational fluid dynamics.
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    Process Safety Progress 17 (1998), S. S3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 142
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    Process Safety Progress 17 (1998), S. 9-15 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design and deflagration pressure relief vents is based on correlations developed for various types of combustible materials and for enclosures of different strengths. The primary guideline for deflagration vent design in the US is NFPA 68 Guide for Venting of Deflagrations [5]. That document gives guidance for the design of vents for enclosures containing flammable gases, specifically hydrogen, coke oven gas, propane, and methane. Application of the guide to other gases is achieved using the KG value. Values of KG are published for a relatively small number of gases, as seen in Table D-1 of NFPA 68. This work present KG data on several additional gases obtained in a laboratory scale test vessel along with analysis of the results with respect to published values of fundamental burning velocity.
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  • 143
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    Process Safety Progress 17 (1998), S. 23-31 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In May 1996, the Flammable and Combustible Liquids Code Committee of the National Fire Protection Association (NFPA) proposed for adoption by the Association a new edition of NFPA 30, Flammable and Combustible Liquids Code. This new edition was the culmination of two and one-half years' work by the Committee and included one of the most significant changes to that document in some twenty years: the incorporation of mandatory fire protection criteria for warehouses and other inside areas that store flammable and combustible liquids in containers and portable tanks.
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  • 144
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    Process Safety Progress 17 (1998), S. 32-38 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes the development of a risk ranked Inspection Recommendation procedure that is used by one of Exxon's chemical plants to prioritize repairs that have been identified during equipment inspection.As part of the Company's Safety Management Practices initiative in the late 1980's a procedure was put into place to ensure that an Inspector's repair recommendations were properly addressed by the organization. The initial procedures were successful at “systematizing” the documentation and stewardship-to-completion of the Inspector's recommendation, however, there were complications with the original process: (1)The Inspector made a simple High, Medium or Low assessment of the priority/criticality of the recommendation. Frequently, this resulted in disagreements with Operations about the true priority of the recommendation.(2)If there was agreement on the priority of the recommendation, there was still disagreement on the relative rank within the priority-which high priority was the highest priority?(3)With limited funds to spend on repairs, it was (and is) important to make sure that the money was being spent on the highest risk items that had the greatest risk reduction/cost benefit ratio.To address these concerns, the procedure was modified to incorporate a risk assessment of the recommendation by both the Inspector and Operations. In the new procedure, the Inspector describes the deficiency that he/she finds and assesses the probability of failure within a certain time-frame. Operations must assess the consequences, from an environmental, safety and economics standpoint, were the failure to occur. These assessments are combined in the typical risk equation (risk = probability × consequences) to arrive at a severity index which serves to rank the recommendation relative to the other recommendations. Because Operations participates in the assessment there is very little disagreement about the priority of the recommendation. The severity index puts the recommendations in order so it is quite clear which are the highest priority recommendations. This process has helped to focus the entire organization on those deficiencies that represent the greatest risk with the result that less time and money is spent correcting items that have a low risk/cost benefit ratio, allowing these savings to be used to reduce the higher risks in the plant.
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    Process Safety Progress 17 (1998), S. 124-126 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple analytical method is presented for estimating the hybrid minimum ignition energy (HMIE) of dust-gas mixtures, based on the assumed generality of Bartknecht's well-known test data for mixtures of propane with a series of dusts in air. Since the HMIE equation requires input data which might be unavailable, the use of conservative default methods is discussed.
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    Process Safety Progress 17 (1998), S. 138-148 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A large and potentially hazardous decrease in aldehyde autoignition temperature (AIT) occurs with increased pressure. The AIT-pressure curve determined in a 5 L stainless steel sphere was similar for propionaldehyde and butyraldehyde in air, falling from about 185°C at atmospheric pressure to 90°C at 140 psia. Reduction of oxygen concentration had little effect on propionaldehyde AIT. At 100°C and 140 psia, autoignitions accompanied by at least a doubling of pressure were observed above 4% oxygen. In the presence of a few grams of free liquid, propionaldehyde vapor ignited in air at initial conditions significantly below the AIT. The mechanism appears to involve rapid Fe-catalyzed exothermic liquid-phase oxidation leading to autoignition of the adjacent heated gas layer. An acetaldehyde vapor-air mixture in the presence of free liquid and rust exploded at room temperature when air pressure was increased to 95 psia; this result is discussed with reference to a cylinder overpressurization that occurred while making up an ostensibly sub-LFL calibration mixture with compressed air. Propionaldehyde's limiting oxygen concentration (LOC) was investigated in the near-autoignition region using the same 5L apparatus; the findings are discussed with reference to an overpressurization incident in an air-liquid partial oxidation reactor. The general results are used to illustrate the application of LOC in partial oxidation processes subject to autoignition and to discuss elements of the current ASTM draft test method for LOC, which does not address test difficulties associated with condensable and/or reactive gas systems.
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    Process Safety Progress 17 (1998), S. F3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Process Safety Progress 17 (1998), S. 157-170 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Risk analysis in chemical process industries is an elaborate exercise involving several steps from preliminary hazard identification to development of credible accident scenarios, to preparation of strategies for prevention or control of damage.All this requires substantial inputs of time and money. In order to get an approximate yet workable assessment of risk at much lesser costs, indices have been developed which link typical findings of elaborate risk analysis to scales of risk. The scales, in turn, provide workable measures of hazards/risks/safety.In the past, indices have been reported for swift risk assessment - the noteworthy among them include Dow fire and explosion index, Mond fire, explosion and toxicity index, IFAL index, and mortality index. A few rapid ranking techniques have also been proposed.This paper presents a new system of methodologies for Hazard Identification and Ranking (HIRA). The system consists of two indices: one for fire and explosion hazards and another for the hazard due to likely release of toxic chemical. The magnitudes of these indices indicate the severity of the likely accident; in terms of the size of the impacted area.HIRA has been applied to a typical chemical process industry - a sulfolane plant - and its performance has been compared with that of the Dow's and the Mond's indices. The study reveals that HIRA is more sensitive and accurate than the other indices.
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    Process Safety Progress 17 (1998), S. 200-208 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 14 Ill.
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  • 150
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    Process Safety Progress 17 (1998), S. 213-218 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On October 31, 1987 a crane lifting a heat exchanger convection section failed and severed a 4″ loading line and a 2″ pressure relief line to an HF alkylation reactor settler drum at a petroleum refinery in Texas City, Texas. Vapors were emitted under pressure for about two hours and the vessel was plugged and drained aproximately 44 hours later. A plume from this accidental release passed through residential areas, damaging some vegetation (brown lawns), and spawning a class action law suit. An extensive analysis was conducted to determine the total inventory loss and to model the blowdown process and the concentrations of HF in the plume. Since the discharge rate was decreasing with time, a peak concentration of HF in the emitted vapors occurred just before the water spray mitigation system became fully operative. Consequently, the mitigation efforts were more effective late in the response when concentrations were already low. The predicted plume concentrations are consistent with observed vegetation damage effects, with concentrations below Emergency Response Planning Guideline Level 3 past 3/4 mile from the source. These results support a policy of sheltering in place during such an event.
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  • 151
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fifty-five gallon steel drum of a liquid organic peroxide pressurized and ruptured in the mix room of a manufacturing plant. The head of the drum blew off and the ejected material ignited. The resulting fire was extinguished by the building sprinkler system and operating personnel. Although there were no injuries, the fire caused significant damage in the mix room. The investigation of this incident, its likely cause, and the corrective actions will be discussed.
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  • 152
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    Process Safety Progress 17 (1998), S. 238-242 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Brazoria County Petrochemical Council, 13 companies that are working together to enhance relations between industry and the community, united in a joint effort at complying with the EPA's Risk Management Program. One of the significant issues the group had to address was the need to develop meaningful hazard assessment for presentation to the public. The EPA's “Table Look-Up Approach” found in the Offsite Consequence Analysis Guidance document is certainly a good tool; however, the built-in conservatism results in over-estimates of potential hazard areas. Much more meaningful results are shown to be obtained using one of the hazard release models.The value of using a credible scenario with realistic meteorological data is demonstrated through the consistently smaller areas predicted by the PHAST Model for planning purposes. Realistic scenarios/failure modes and realistic model parameters are important so that the risk to the public is not overstated. Proprietary models such as PHAST are invaluable in providing more meaningful consequences for planning purposes.
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  • 153
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    Process Safety Progress 17 (1998), S. 263-271 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some of the hazards encountered by process plant operators involve the operation of in-line valves to control, start, and to stop flow. Torque required to operate valves may vary according to valve wheel size, in-line pressure, and valve flange position (open/closed). This study determined how valve wheel size, in-line pressure and valve position (open/closed) affect torque required to actuate a valve. Data were gathered with each combination of size, pressure and position for 336 valves in an operating petrochemical process facility. The results indicate that the main effects of valve wheel size, the in-line pressure, and open/closed valve position significantly affect operational torque requirements. In addition, the interaction between position and pressure was significant for operational torque. The implication of these results is that operators are exposed to operational torque requirements that exceed maximum acceptable capabilities that have been determined in previous studies.
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  • 154
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    Process Safety Progress 17 (1998), S. 288-296 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An ammonia storage tank was built at the BASF Antwerp site in 1969 on land reclaimed from the sea. After several years of operation uneven foundation settlement, of up 2, occurred. In order to assure stability of this area for the next operation period (at least 10 years) measures were taken to ensure continued safe operation. One key measure was strain gauge monitoring at the location of maximum stress.
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  • 155
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    Process Safety Progress 17 (1998), S. 297-301 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Baker-Strehlow methodology was developed to provide an objective approach to prediction of blast pressures from vapor cloud explosions. The complete methodology was first published in 1994 [1]. Since then, it has evolved through ongoing research and use in VCE hazard analyses, facility siting studies and accident investigations. This article gives a brief overview of a paper on recent developments in the Baker-Strehlow methodology presented at the 31st Loss Prevention Symposium in Houston on March 9-13, 1997. Because the entire paper is too lengthy to be presented here, the following discussions may be lacking in some details. A copy of the complete paper can be obtained from the American Institute of Chemical Engineers (AIChE).Since the Baker-Strehlow method was first published, it has been used extensively in VCE hazard assessments in refineries and chemical plants. As expected, many practical lessons have been learned during the course of the hazard assessments, and the Baker-Strehlow method has evolved as a result. The changes have been evolutionary, not revolutionary. In keeping with the goals of the original study in which the methodology was developed, all changes have been incorporated with the intent of achieving an objective methodology to provide consistent prediction of VCE blast effects.The revisions to the Baker-Strehlow method resulting from experience gained during plant walk-downs and hazard assessments include: Systematic identification of “potential explosion sites” or “PESs,”Selection of the level of confinement for mixed zones of 2D and 3D confinement,Deciding on flame expansion when confinement is elevated above the vapor cloud,Selecting the reactivity for a fuel that is a mixture of fuels with differing reactivities,Predicting blast loads when there are multiple PES's within a vapor cloud considering different ignition source locations.
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  • 156
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    Process Safety Progress 17 (1998), S. 83-85 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Safety, health and loss prevention are major areas of interst for the American Institute of Chemical Engineers (AIChE). There has been an evolution of these concerns over the years in the Institute just as it has in industry. This article chronicles this evolution.
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  • 157
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    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 158
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    Process Safety Progress 17 (1998), S. 1-8 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recent guidelines released by the U.S. EPA define a worst-case scenario as a release under stable atmospheric conditions defined as Pasquil-Gifford stability class F. Unfortunately, very few tests at F stability have been available heretofore to provide a basis for models. Recent test data with propane releases by the German research organization TUV provide a set of 60 experiments conducted specifically to define the effects of atmospheric stability class on dispersion. Of these, 25 tests were at F stability. A comparable number were at each other stability class A through E. In addition 23 tests were at wind speeds under 1.5 m/s in stable atmospheres. This paper reports on adjustments made to our models based on these new data by reducing the originally-postulated sensitivity to stability class. In spite of considerable scatter in the TUV data, particularly between two different types of propane analyzers, the model allows us to extract information by averaging over the tests.
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  • 159
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    Process Safety Progress 17 (1998), S. 16-19 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A multi-disciplinary team developed a guideline for determining access restriction zones around vented solids handling equipment. The guideline provides a method for ensuring the discharge from a vented explosion will not cause injury to personnel. The steps in this method include: calculating the extent of external hazards from vented explosions; identifying potential areas where personnel could be exposed to a hazard; identifying ways to eliminate or reduce the hazard area; and establishing and documenting any access restrictions needed. Hazard zone calculations use the latest knowledge from research into fireball size, flame length and external pressure equations in VDI 3673. The guideline provides guidance for using this information. Options for mitigating or reducing external hazards from vented explosions are also described. As part of the project, the team audited several solids handling systems to look for potential oversights in existing restricted access areas. Some of the team's learnings from these audits are reviewed.
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  • 160
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    Process Safety Progress 17 (1998), S. 43-48 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper defines situation awareness (SA) and discusses its importance to operator-machine system safety and functioning in the context of process control activities. Specifically, identified are relationships of human detection of critical process cues converying the status of automated control systems and operator interpretation of the meaning and relevance of such information to the potential for negative incidents in chemical processing. Beyond individual operator SA in interacting with control systems, intra- and inter- work team SA are discussed for supporting individual attainment of process control responsibilities. Factors critical to team SA are discussed. “Road blocks” to team SA are also analytically examined. Lastly, methods for assessing individual and team SA are reviewed and vehicles for relating outcomes of these methods to changes in process control operator and team behavior to improve human-machine system safety and performance are relayed.
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  • 161
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    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 162
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    Process Safety Progress 17 (1998), S. 74-81 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of the ingition behavior of dust-air mixtures due to electrical sparks (MIE, Minimum Ignition Energy) and hot surfaces (MIT, Minimum Ignition Temperature) is important for risk assessments in chemical production plants. The ignition behavior determines the extent and hence the cost of preventive protection measures.This paper describes the use of the minimum ignition energy and minimum ignition temperature as very important safety indexes in practice.Based on the latest results from large scale experiments on pneumatic filling of silos with polymeric materials and new results of full scale filling tests using Flexible Intermediate Bulk Containers (FIBC) manufactured from a variety of materials, guidance can be given to ensure safe operation in different situations such as filling, emptying operations, type of powder handled.The aim of this paper is to assist people dealing with product. It reflects the present state of the art and current knowledge of the assessment and measures associated with powder handling.
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  • 163
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    Process Safety Progress 17 (1998), S. 104-106 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In mid-1997, an Advanced Process Control (APC) scheme was implemented at a resins manufacturing complex with the goal of minimizing flare fuel gas usage while maintaining sufficient energy (BTU/SCF flare gas) to be in environmental regulatory compliance. Prior to APC implementation, the flare system was manually controlled by plant operators with minor attention paid to the minimization of fuel gas usage. Since implementation, APC has saved the plant thousands of dollars in fuel gas costs and reduced unnecessary combusted fuel gas emissions.Hazard analysis techniques were used in the development of the control scheme. An overview of the APC used, the economic evaluation, and the hazard analysis techniques used in the project are presented here.
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  • 164
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    Process Safety Progress 17 (1998), S. 107-123 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the risk assessment parlance, especially with reference to chemical process industries, the term “domino effect” is used to denote “chain of accidents,” or situations when a fire/explosion/missile/toxic load generated by an accident in one unit in an industry causes secondary and higher order accidents in other units. The multi-accident catastrophe which occurred in a refinery at Vishakhapatnam, India, on September 14, 1997, claiming 60 lives and causing damages to property worth over Rs 600 million, is the most recent example of the damage potential of domino effect.But, even as the domino effect has been documented since 1947, very little attention has been paid towards modeling this phenomena. In this paper we have provided a conceptual framework based on sets of appropriate models to forecast domino effects, and assess their likely magnitudes and adverse impacts, while conducting risk assessment in a chemical process industry. The utilizability of the framework has been illustrated with a case study.
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  • 165
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    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 166
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    Process Safety Progress 17 (1998), S. 149-154 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article deals with fire protection for water miscible flammable liquids stored in plastic containers packaged in boxes located on pallets. A series of fire tests was conducted with palletized rack storage arrangements using in-rack sprinkler protection at various levels. The intent of the paper is to present data from this test series for these types of commodities. The paper will identify various existing water miscible flammable liquid products stored in this fashion and provide background information for protecting this type of storage as it relates to NFPA 30 Flammable and Combustible Liquids Code. The test data indicates that further research work is needed in the area of plastic containers for use with the storage of combustible and flammable liquids. Included in the paper are discussions concerning possible protection strategies and suggestions for future research which would benefit those involved in risk management of this type of commodity.
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  • 167
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    Process Safety Progress 17 (1998), S. 176-183 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The safest method to prevent fires and explosions of flammable mixtures in the first place. This method requires detailed knowledge of the flammability region as a function of the fuel, oxygen, and nitrogen concentrations. A triangular flammability diagram is the most useful tool to display the flammability region, and to determine if a flammable mixture is present during plant operations.This paper describes how to draw and use a flammability diagram. A procedure to estimate the flammability region using the available and sometimes limited data is discussed. The paper also shows how to use the flammability diagram with plant operations involving inerting and purging, and from bringing vessels into and out of service. A compilation of flammability diagrams for 30 materials, based on previously published data is provided.An automated apparatus for acquiring data for a flammability diagram is described. The apparatus consists of a 20-L sphere with an automated gas mixing system, a fuse-wire ignition system, and a high speed pressure measurement and data acquisition system. Data derived from the apparatus includes flammability limits, maximum pressure during combustion, and the maximum pressure rate. The effect of fuse-wire ignitor dynamics on the results is studied. A flammability diagram for methane drawn from data obtained from the apparatus, is presented.
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  • 168
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    Process Safety Progress 17 (1998), S. 86-97 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Regulatory issues related to material safety have made the accurate measurement and/or prediction of flash points essential. The flash point is one of the major physical properties used to determine the fire and explosion hazards of a liquid. Flash points are used by virtually all governmental entities worldwide to define “flammable” and “combustible” materials for shipping and safety regulations.A model is described here for the calculation of closed cup flash points for multicomponent, single liquid phase, mixtures. The model is based upon rigorous vapor/liquid equilibrium calculations supplemented with information about the lower flammable limits (LFL's) and heats of combustion (ΔHc's) for the mixture's constituent components. The closed cup flash points predicted with this model are typically within ± 5°C of the experimentally reported values. Such a model is useful as a means of verifying experimental data and as a tool for screening product formulations prior to experimental flash point determination. The model should considerably enhance the safety evaluation portion of the product development cycle, thus leading to shortened product time-to-market cycles. While flash points calculated with this model are in excellent agreement with experiment, experimental determination is still encouraged for critìcal safety applications.
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  • 169
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    Process Safety Progress 17 (1998), S. 134-137 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: National Advisory Committee's Acute Exposure Guideline Levels (AEGLs) for ammonia are critically evaluated. The technical bases for concern about AEGL-2 and AEGL-3 values derived by the committee are summarized recommendations made.
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  • 170
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    Process Safety Progress 17 (1998), S. 127-133 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An explosion and flash fire in a fixed bed reactor occurred at a municipal wastewater treatment plant (WWTP). Two employees were injured in the accident. The accident occurred in an ozone treatment building where ozone was used to treat odors from the offgas of the sludge concentration units. Excess ozone manually was routed to the fixed bed reactor (ozone destruct unit) where the ozone is catalytically transformed into oxygen before being discharged to the atmosphere.An investigation of the accident was conducted to determine the root cause of the explosion and flash fire and identify corrective actions which the WWTP management could undertake to prevent a recurrence. This investigation included site inspections, interview with the injured employees, sampling and analysis of various materials, an explosion dynamics analysis, and a root cause analysis.It was concluded that cooling oil from one of the ozone generation units entered the main ozone gas line due to a crack in one of the reactor's dielectric tubes. The cooling oil was vented into the ozone destruct unit when an employee opened a ball valve on the main ozone gas line. The cooling oil, essentially a saturated hydrocarbon mixture, reacted exothermically when it contacted the manganese dioxide catalyst. The exothermic reaction resulted in an explosion which propelled the access panel outwards and dispersed the catalyst pellets. A flash fire followed the explosion. The flash fire burned two employees and caused thermal damage to a nearby control panel.Although this accident was the first of its kind at this facility, this was not the first time that the ozone generator had experienced a failure of a dielectric tube. Thus, there was a significant probability that a dielectric tube failure could leak cooling oil into the main ozone gas line. This failure event could, in turn, result in another explosion and flash fire. The WWTP staff neither designed nor fabricated the ozone generator-destructor system. Therefore, it did not seem appropriate for the WWTP staff to modify the ozone system. Instead, it was recommended that the ozone destruct unit be taken out of service. The WWTP management acted on this recommendation.
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    Process Safety Progress 17 (1998), S. 171-175 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An explosion occurred in a petroleum product storage tank at a refinery. The liquid petroleum product was a heavy oil used as an asphalt extender. There were no injuries, but the cleanup was costly. The storage tank was one of several which received the product stream from a dehydration unit. The accident occurred shortly after the refinery was brought back on-line following a shutdown for schduled maintenance.This was the first incident of this kind to occur at this facility. Analysis of the process data and eyewitness observations indicated that the dehydration tower, which was supposed to be maintained at a minimum of 100°C during the shutdown, was allowed to drift below 100°C for an unknown period of time. This deviation enabled liquid water to enter the storage tank. Three operational factors contributed to the accident. Corrective actions were recommended to prevent a recurrence of a similar incident.
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    Process Safety Progress 17 (1998), S. 184-189 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dust explosions have been with us for a long time. The first record of a dust explosion occurred in Turin, Italy, on December 14, 1785 [1]. The detailed record of this event is left to us by Count Morozzo. The event took place in Mr. Giacomelli's bakery. We know from his account that the weather was unseasonably dry, that a boy who worked in the bakery was using a shovel to stir and transfer the flour to a chute from a store room to the bakery and he had a lighted lamp to work by. The rest, as the saying goes, is history. No one was killed, and the building was saved by the sagacious fact of having plenty of windows. Since that first record, of course, there have been many explosions with much loss of life and significant economic consequences.
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    Process Safety Progress 17 (1998), S. 190-195 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The RSST DIERS vent sizing methodology is revised to provide realistic design equations for reactive systems consistent with available large-scale experience. Using easy to obtain RSST data such as rate of temperature rise and rate of pressure rise excellent agreement is illustrated for hybrid, vapor and gassy reactive systems.
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    Process Safety Progress 17 (1998), S. 196-199 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: From the 1960s onwards, the chemical and oil industries developed and used a number of new safety techniques which, in time, became second nature to those who applied them. They included the use of QRA for deciding priorities, Hazop and audits for identifying problems, inherently safer design for avoiding hazards, and more thorough investigation of incidents for identifying underlying causes. However, it has not yet become second nature to remember the accidents of the past and the actions needed to prevent them happening again.I joined industry in 1944 and moved to production in 1952. Then, and for at least 15 years afterwards, safety was a non-technical subject that could be left to arts graduates and elderly foremen. There was concern that people should not be hurt - great attention was paid to the lost-time accident rate - but there was no realization, that it was a subject worthy of systematic study by experienced technologists.This view changed at the end of the 1960s. A new generation of plants had been built, operating at higher temperatures and pressures and containing larger inventories of hazardous chemicals; the result was a series of fires and explosions and a worsening fatal accident rate. Figure 1 shows the situation in ICI, at the time the UK, s largest chemical company. Other companies experienced a similar state of affairs.As a result in 1968, I was appointed one of the company's first technical safety advisers, an unusual appointment at the time for someone with my experience, and if the reason for my appointment had not been so obvious I would have wondered what I had done wrong. I and my colleagues tried to apply the same sort of systematic thinking to safety that we applied in our other professional work. We developed some new concepts and techniques and adopted others. A common feature of our ides, realized only in restrospect, was that they consisted of more than mere problem-solving techniques. Once people had got used to these new concepts and used them a few times, they began to look at a whole range of problems in a different way.
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    Process Safety Progress 17 (1998), S. W3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Process Safety Progress 17 (1998), S. 259-262 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Case histories of 65 incidents in runaway reactions and emergency relief in Taiwan were analyzed and classified into several categories according to their causes, materials involved, equipment types, reaction types, and ignition sources. The cases in reactors and storage tanks were examined in more detail owing to the higher probability or larger potential hazard in these two types of equipments. The most common consequence of the incidents are explosions, fires, and atmospheric release of toxic chemicals. The most severe case was a thermal explosion from an organic peroxide storage area which caused the death of 33 persons. Popping and direct releasing of process chemicals to the atmosphere from relieving devices cause the greatest environmental concerns to the community close to the plants. Runaway reactions in batch type reactors occur frequently due to various operational mistakes. Heat of reaction is the most frequent ignition source of runaway reactions and emergency relief.
    Additional Material: 1 Ill.
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  • 177
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    Process Safety Progress 17 (1998), S. 272-277 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: EPA's Risk Management Program regulation, promulgated in June 1996 as 40 CFR Part 68 requires subject industries to submit Risk Management Plans by June 1999. This plan requires hazard assessment of the operations of a facility using worst case scenarios and alternative releases. EPA has provided an Off-site Consequence Analysis (OCA) guidance to help facilities in their hazard assessment.OxyChem will be significantly impacted by the RMP rule. This paper outlines OxyChem's general experience and its strategy in planning to comply with this rule. OxyChem's approach in the development of the scenarios required by the rule is described in this paper. Limitations involved in the use of EPA's look-up tables or a single modeling solution for conducting all of the OCA are discussed. A three tiered OCA approach is presented as a possible alternative.
    Additional Material: 4 Tab.
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  • 178
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    Process Safety Progress 17 (1998), S. 209-212 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: HFC-227ea (CF3CHFCF3;1, 1, 1, 2, 3, 3, 3-heptafluoropropane) is an effective replacement for Halon 1301 in fire suppression systems, providing rapid extinguishment of flames through a combination of physical and chemical mechanisms. The vast majority of applications for HFC-227ea involve the protection of Class A hazards, which are characterized by low fuel loadings and low energy output, with fire sizes often in the range of 5-10 kW. Mid- and large-scale testing has demonstrated that HFC-227ea, at its minimum design concentration of 7.0% v/v, is effective at extinguishing fires typical of those expected to occur in electronic data processing (EDP) facilities, telecommunication facilities and anechoic chambers. The levels of HF produced following extinguishment of typical Class a fires with HFC-227ea were well below the estimated mammalian LC50 and the human Dangerous Toxic Load (DTL), and do not appear to present a threat to electronic equipment.
    Additional Material: 4 Ill.
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  • 179
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    Process Safety Progress 17 (1998), S. 219-224 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sandia National Laboratories (Sandia) has refined a process for developing inherently safer system designs based on methods used by Sandia to design detonation safety into nuclear weapons. The process was created when Sandia realized that standard engineering practices did not provide the level of safety assurance necessary for nuclear weapon operations, with their potential for catastrophic accidents. A systematic approach, which relies on mutually supportive design principles integrated through fundamental physical principles, was developed to ensure a predictably safe system response under a variety of operational and accident-based stesses. Robust, safe system designs result from this thematic approach to safety, minimizing the number of safety critical features. This safety assurance process has two profound benefits: the process avoids the need to understand or limit the ultimate intensity of off-normal environments and it avoids the requirement to analyze and test a large array of accident environment scenarios (e.g., directional threats, sequencing of environments, time races, etc) to demonstrate conformance to all safety requirements.
    Additional Material: 3 Ill.
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  • 180
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    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 181
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    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 233-237 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method is described to enhance the management of process safety risks such that the number and type of safety systems protecting against any hazard are consistently predicated upon risk. Further, that such an assignment of safety systems can be made consistent throughout an organization. This consistency is gained through standardization of qualitative risk ranking and by setting company guidelines.
    Additional Material: 4 Ill.
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  • 182
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    Process Safety Progress 17 (1998), S. 243-258 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Research was carried out to develop improved protection guidelines for silane handling systems through enhanced understanding of the behavior of releases of this pyrophoric gas. The approach involved addressing three aspects of the problem: the prompt ignition behavior of silane; the reactivity characteristics of quiescent silane/air mixtures; and the rates of reaction of silane leaked into enclosures with and without explosion venting, in the presence of ventilation air flow. A first conclusion, reached from tests in a ventilated cabinet, was that, contrary to prevailing belief, the ventilation flow has no measurable effect on the prompt ignition of the release. From experiments in a 5.1-liter (311-in.3) sphere it was found that silane/air mixtures of concentrations between 1.4 and 4.1% (by volume) are explosive but stable. In this case, piloted ignition tests yielded laminar burning velocities up to 5 m/s (1000 ft/min). Mixtures between 4.5 and 38% (the maximum reached in the tests) were found to be metastable, and would undergo spontaneous ignition after a delay ranging from 15 to 120 seconds, with the shorter values corresponding to higher silane concentrations. Experiments were also performed in a 0.645-m3 (22.8-ft3) vessel both with and without explosion venting, to measure the rates of energy release associated with impulsively-started silane leaks from 1/8 and 1/4-in. (3.2 and 6.4-mm) lines. A method for the prediction of the venting requirements of partial-volume deflagrations (PVD) was evolved into a tool to quantify the pressure rise from ignition of silane leaks in enclosures. These results represent a significant step toward updating existing design recommendations which prescribe ventilation requirements that are based on outdated and, in some instances, misinterpreted data.
    Additional Material: 15 Ill.
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  • 183
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    Process Safety Progress 17 (1998), S. 278-287 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas explosion simulators are often used as tools in process plant design. This article presents some properties of gas explosions found using the EXSIM simulation software on three offshore modules with a total of nearly 10,000 simulations. The selected results are chosen for their supposed applicability to structural design in the process industries.Generalized data are presented for the effect of gas cloud size, explosion impulse vs. explosion pressure, pressure and impulse vs. duration, the probability of a “short” explosion, loading rate, pressure-time “shape” function, and the effect of introducing louvers.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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