Basic Documentation

Table Of Contents
Laboratory Ventilation Codes and Standards
Siemens Industry, Inc. 34
Topic Requirement(s) Commentary
(Special
Purpose)
Perchloric
Acid
(Continued)
A8.11.8 Perchloric acid hoods should be washed down after each use.
8.11.8.1 The hood work surface shall be watertight with a minimum depression of 13
mm (1/2 in.) at the front and sides.
8.11.8.2 An integral trough shall be provided at the rear of the hood to collect wash-
down water.
8.11.9 The hood baffle shall be removable for inspection & cleaning.
8.11.10 If a chemical fume hood or exhaust system was used for perchloric acid
heated above ambient temperature, tests shall be conducted for explosive
perchlorates before any inspection, cleaning, maintenance, or any other work is done
on any part of the exhaust system or hood interior.
8.11.11 Prior to using a perchloric acid hood for any purpose, the hood shall be water-
washed and shall be tested according to 8.11.9 to ensure residual perchlorates are
not present.
12.1.2.5 Strong oxidizing materials, such as perchloric acid, shall not be heated by
gas flames or oil baths.
American Conference of Governmental Industrial Hygienists (ACGIH)
INDUSTRIAL VENTILATION A Manual of Recommended Practice, 27th Edition
VS-35-03 (PERCHLORIC ACID HOOD DATA)
1. Do not use perchloric acid in a hood designed for other purposes. Identify
perchloric acid hoods with large warning signs.
2. Provide exhaust ventilation and room supply air with minimal challenge to hood.
3. Utilize local exhaust ventilation within the hood to minimize condensation of vapors
inside the hood.
4. Locate all utility controls outside the hood.
5. Materials of construction for this type of hood and duct must be nonreactive, and
acid resistant, and relatively impervious. AVOID ORGANIC MATERIALS unless
known to be safe. Stainless steel type 316 with welded joints is preferred.
Unplasticized polyvinyl chloride or an inorganic ceramic coating, such as porcelain,
is acceptable.
6. Ease of cleanliness is paramount. Use stainless steel with accessible rounded
corners and all welded construction.
7. The work surface should be watertight with a minimum of 0.5 inch dished front and
sides and an integral trough at the rear to collect the washdown water.
8. Design washdown facilities into the hood and duct. Use daily or more often to
thoroughly clean perchloric acid from the exhaust system surfaces.
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