MIL-HDBK-1191
shall comply with requirements of the Nuclear Regulatory Commission.
8.16.4.4
Canopy Hoods for Prosthetic Dental Laboratories. Canopy hoods
for Prosthetic Dental Laboratories, and exhaust ductwork extending for a
distance 3000 mm (10 ft) downstream from the hood connection, shall be
fabricated of material which is corrosion resistant to the caustic fumes
emanating from boil-out tanks and casting activities conducted in the
laboratory.
8.16.4.5
Biological Safety Cabinets (BSCs). Class, Type, and location
of BSCs shall be as directed by the using agency. Class II BSCs are
provided with HEPA filtration of recirculated air and/or building exhaust,
and are provided in such areas as Microbiology and Mycology. The required
open door/sash face velocity for Class I and Class II Type A BSCs shall be
0.381 m/s (75 fpm), and for Class II Types B1, B2, and B3, shall be 0.508
m/s (100 fpm). For further information of biological safety hood Class,
Type, application, and exhaust requirements, refer to references 8a, 8r,
8s, and 8t.
8.16.4.6
Perchloric Acid Hoods. Hoods for handling of perchloric acid
and other strong oxidizing agents, and the associated exhaust ductwork,
shall be constructed of stainless steel. Internal water spray systems
shall be provided for hood and all ductwork to facilitate the periodic
washdown. Joints shall be welded and ground smooth, and all ductwork
pitched back toward the hood to facilitate drainage. More detailed
guidance is provided by the ACGIH publication.
8.16.4.7
Containment Laboratories BL-3 and BL-4). These laboratories
deal primarily with indigenous or exotic agents which may cause serious or
potentially lethal disease as a result of exposure by inhalation. The HVAC
design for these laboratories shall assure the continuous negative
pressurization and exhaust of the space. The exhaust air from these spaces
shall not be recirculated to any other area of the building, but shall be
transported through dedicated exhaust ductwork to be directly discharged to
the outside of the building. Design of BL-3 and BL-4 laboratory exhausts
shall comply with latest editions of OSHA and other Federal regulations.
8.16.5
Exhaust Canopies. Exhaust canopies shall be provided for
equipment or appliances generating high heat or moisture (steam) loads,
such as glassware washers, boilout tanks, drying ovens, sterilizers, and
stills, as required. In some cases, specially designed canopy hoods may be
necessary to control personnel exposure to hazardous chemical vapors.
Canopy hood design shall comply with the ACGIH data for "Canopy Hood"
(reference 8b).
8.16.6
Laminar Flow Clean Benches. These horizontal flow hoods shall
be used in pharmacy for preparing intravenous fluids and similar laboratory
processes. Clean benches recirculate room air and do not require exterior
air supply or exhaust systems.
8.16.7
Bench-Back Slot Hoods. Slot hoods are typically built into the
wall behind laboratory benches to exhaust vapors, gases, and odors that are
released with little energy or velocity. Typical applications are
laboratories, brace shops, and other spaces in which volatile chemicals are
routinely used. Design of these hoods shall be in accordance with ACGIH
8-20
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