25 October 2004
6-2, to uniformly distribute airflow over the entire cross-section of the enclosure.
Figure 6-2. Crossdraft blast enclosure.
For mechanically supplied replacement air, use maximum plenum take-off width
of 2.44 m (8 ft). Plenum serves as material door.
Perforated plate with 9.53 mm (3/8-in) holes. Size open area for an airflow
velocity of 10.16 m/s (2000 fpm) through holes.
Size the exhaust plenum for a maximum plenum velocity of 5.08 m/s (1000 fpm).
Size any supply plenum for a maximum plenum velocity of 2.54 m/s (500 fpm).
Lift up flap to remove material from behind plenum.
Perforated plate, from floor to ceiling and wall-to- wall, with 9.53 mm (3/8-in)
holes. Size open area for an airflow velocity of 5.080 m/s (1000 fpm) through
Hinged plenum equipment doors.
Access Doors and Observation Windows. Provide an observation
window and an access door in accordance with 29 CFR 1910.94(a)(3)(i)(d) and (e) and