P74 Series Differential Pressure Controls
The controls are available for applications sensing air, oil or liquid.
Typical applications are proof of flow across a chiller or water cooled
condenser, proof of flow in a heating or cooling coil and lube oil
pressure sensing on refrigeration compressors. On a proof of flow
application the control measures pressure drop across two different points
in either a closed water circulating system or a city water to supply
These differential pressure controls are for use as operating controls
and/or indicating system functions through display lights or panels. They
measure the difference in pressure exerted upon its two sensing elements.
On a proof of flow application in a water chiller system the control
activates a light or signal to indicate a loss of water. The control may
also be applied as a lube oil pressure sensing control on refrigeration
compressors. They may be used in combination with P28 and/or P45 oil
pressure cutout controls on two compressor, single motor units to reduce
the oil system cost. Special low pressure models are available for
variable speed and screw compressor oil pressure applications.
Replaces Part Numbers:
All Series P74 differential pressure controls are designed for use only as
operating controls. Where an operating control failure would result in
personal injury and/or loss of property, it is the responsibility of the
installer to add devices (safety, limit controls) or systems (alarm,
supervisory systems) that protect against, or warn of, control failure.