25 October 2004
Figure 2-4. Plenum design without perforated duct.
Perforated Duct Design. Use perforated duct to evenly distribute the
flow of replacement air inside a plenum or use alone when ceiling height is greater than
4.58 m (15 ft). Manufacturers provide several different types and sizes of perforated
duct. Use recommendations from the manufacturer for duct design. The manufacturer
will not only recommend the size, shape, and type of the required perforated duct, but
also the location of the orifices and reducers to distribute the air properly.
CONTROLS. Provide industrial ventilation system controls and
associated alarms to ensure contaminant control, space specific balance and
conditioning, a safe and healthy work environment, and system malfunction notification.
Gauges and Sensors. Specify gauges and sensors to provide
continuous monitoring of system performance. The minimum requirements are:
Differential pressure sensors, with gauge readouts, across each
replacement air filter section. Set points on the gauge to trigger an alarm when the
pressure drops or gains across the filter exceed the manufacturer's recommended
value. A pressure drop occurs when there is a blow through a filter and a pressure gain
occurs when the filter gets loaded.
Operating light on replacement air system fan motor.