2.11.3.2 RADIOISOTOPE HOODS (H3)
(a) Provide a dedicated exhaust system for each H3 type hood
(b) The exhaust air quantities and pressure drops are listed below in Table
2-13:
Table 2-13 H3 Hood Exhaust Air Requirements
Size mm
Exhaust Cu M/Min
Pressure Drop Pa
(Inches)
(CFM)
(Inches of Water)
1200 (48)
24.5 (875)
93 (0.375)
1500 (60)
31.5 (1125)
93 (0.375)
1800 (72)
38.5 (1375)
93 (0.375)
(c) Provide a HEPA filter in exhaust air duct prior to discharge at or above
the highest point of the building.
(d) Provide an alternate room exhausts air connection so exhaust air may be
drawn from the room grille when the hood is not in operation. Provide
motorized dampers in each branch and an airflow control valve to ensure
constant static pressure in each branch. See VA Standard Detail 15900-8. The
minimum static pressure drop to operate the valve shall not exceed 93 Pa
(0.375 Inches of Water).
(e) The ductwork shall be all welded stainless steel.
(f) See Article 2.16 for emergency power requirements.
2.11.3.3 FUME HOODS H7/H13: H7 and H13 hoods have identical requirements with
the exception of the make-up air system. The H7 hoods use all room air as the
make-up air for exhaust; the H13 hoods use 60 percent auxiliary make-up air
directly ducted to the hoods and remaining 40 percent air comes from the room
for their exhaust needs.
(a) Provide a dedicated exhaust system to serve not more than four H7 or H13
hoods.
(b) The exhaust air quantities) and pressure drops for H7 and H13 hoods are
listed below in Table 2-14.
Table 2-14 H7/H13 Hood Exhaust Air Requirements
H7 Hoods
H13 Hoods
Pressure Drop
ExhaustH Make-up
Total
Auxiliary
Room
Size mm
Exhaust
H13 ONLY
7/H13
Cu M/Min
Cu M/Min
Cu M/Min
(Inches) Cu M/Min
Cu M/Min Cu M/Min
(CFM)
(CFM)
(CFM)
(CFM)
(CFM)
(CFM)
900
19
7
11
18
89
7
(36)
(625)
(250)
(375)
(625)
(0.36)
(0.03)
1200
25
10
15
25
75
17
(48)
(875)
(350)
(525)
(875)
(0.30)
(0.07)
1500
32
13
19
32
89
55
(60)
(1125)
(450)
(675)
(1125)
(0.32)
(0.22)
1800
39
15
23
39
60
82
(72)
(1375)
(550)
(825)
(1375)
(0.24)
(0.33)
HVAC DESIGN MANUAL
2-32
HVAC SYSTEMS AND EQUIPMENT
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