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Evaluation of industrial local exhaust hood efficiency by a tracer gas technique.

Authors
Hampl-V
Source
Am Ind Hyg Assoc J 1984 Jul; 45(7):485-490
NIOSHTIC No.
00140308
Abstract
The efficiency of an industrial local exhaust hood was evaluated by a tracer gas technique. Sulfur-hexafluoride (2551624) (SF) was sampled in the duct, and its concentration was determined by gas chromatography (GC). SF was continuously released under controlled conditions from an SF source located in the hood duct inlet. The SF source was then positioned at various locations around the hood or at locations where industrial contaminants might originate. SF was again measured in the duct. The concentration found was compared with that released in the hood duct inlet. The ratio of these values (expressed in percent) was considered as the hood efficiency at a specific point. Three basic parameters were critical to the proper evaluation of the technique: proper SF detection conditions, proper sampling location, and proper SF discharge conditions. An increase of the GC column temperature, up to 100 degrees-C, resulted in a shorter elution time for oxygen peak; SF elution time remained virtually unchanged. Changes of pressure across a glass fiber filter connected to the GC column did not significantly affect SF peak height. The duct center line was determined as the best position for the sampling probe. A lower SF concentration was found in the duct where the tracer discharge velocity was higher than that of the air flow. The author concludes that the tracer gas technique is capable of directly evaluating the hood efficiency associated with fumes, gases, and vapors or very fine particles.
Keywords
NIOSH-Author; Exhaust-hoods; Industrial-ventilation; Control-equipment; Gas-chromatography; Quantitative-analysis; Air-monitoring; Air-quality-control; Equipment-design; Sampling-methods
CODEN
AIHAAP
CAS No.
2551-62-4
Publication Date
19840701
Document Type
Journal Article
Fiscal Year
1984
NTIS Accession No.
NTIS Price
Issue of Publication
7
ISSN
0002-8894
Source Name
American Industrial Hygiene Association Journal
State
ME
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