25 October 2004
Static pressure sensor at the outlet of the replacement air fan with a
gauge readout. Set the points on the gauge to trigger an alarm when the pressure is
lower than the recommended range (as determined by baseline testing).
Hood static pressure sensor, for critical processes or process where
extremely toxic substances are used, with a gauge mounted in a conspicuous place
near the hood. Set the points on the gauge to trigger an alarm when the static pressure
is lower or higher than the recommended range (as determined by baseline testing). Do
not use the type of inline flow sensor, which measures the pressure drop across an
orifice plate. Use only a static pressure tap and differential pressure gauge.
Differential pressure sensor across each exhaust air-cleaning device with
gauge readout. Set points on the gauge to trigger an alarm when the pressure drop
across the device exceeds the manufacturer's recommended value.
Static pressure sensor at the exhaust fan inlet with gauge readout. Set
the points on the gauge to trigger an alarm when the pressure is lower than the
recommended range (as determined by baseline testing).
Operating light on exhaust air system motor. When a sensor indicates a
malfunction, trigger an alarm that is both audible and visible in the shop space.
Operating ranges on all gauges clearly marked. Locate gauges on an
annunciator panel (except hood static pressure gauges). Provide a 3-way valve at each
gauge connection for cleanout and calibration; see Figure 2-5.
Place room differential pressure sensors away from doors, windows, and
replacement air discharge.
Interlocks. Provide an interlocked on-off switch so that the replacement
air and exhaust air systems operate simultaneously. When there are multiple fans,
clearly label which exhaust fan is interlocked with which supply fan.
Annunciator Panel. Provide an annunciator panel to continuously
monitor ventilation system performance. Locate the panel so it is accessible to shop
personnel. The panel must include, but is not limited to, all gauges (except hood static
pressure gauges) described in paragraph 2-5.1. Mount fan motor operating lights and
interlocked ON/OFF switch on the panel. The interlocked switches must clearly show
which exhaust and supply fans are interlocked, where multiple fans are used. The
panel should indicate what action to take when operation falls outside the prescribed
ranges. For example, "examine/replace filter on R.A. unit when this gauge reads
outside indicated range."