The PS4 is used to sense the static pressure in the supply
air duct and maintain the static pressure set point limit
that the system will operate at. The PS4 will control an ND
or URD damper, to allow an adequate amount of pressure
to by-pass from the supply plenum to the return duct or
dump zone, and maintain design static pressure and
velocity. The PS4 has a range of 0.1" to 4.0" W.C. The PS4
can be used with motor actuators to create model EBD bypass dampers.