FAIRCHILD High Flow Positive Bias Relay (M1500A)

FAIRCHILD High Flow Positive Bias Relay (M1500A)

Main Features

  • Control sensitivity of 1″ water column.
  • Large Supply and Exhaust Valves.
  • Soft Supply and Exhaust Valve seats.
  • A balanced Supply Valve.
  • Aspirator Tube design.
  • A separate Control Chamber.
  • Unit construction.


  • Allows use in precision applications.
  • Provides high forward and exhaust flows.
  • Minimizes air consumption.
  • Minimizes the effect of any supply pressure variation.
  • Compensates downstream pressure droop under flow conditions.
  • Isolates the diaphragm from the main flow to eliminate hunting and buzzing.
  • Allows you to service the Model 1500A without removing it from the line.

The Model 1500 Positive Bias Relay is designed for applications that require an output pressure that is the sum of a controlled input signal plus a fixed bias. This pneumatic relay provides high output flow at an output pressure that represents the input signal pressure plus a preset bias. The output of the relay is the sum of the spring bias, set with the Range Screw, plus a pneumatic input signal. (Po = Ps + K); where Po is output pressure, Ps is signal pressure, and K is the spring constant set by the Range Screw.

Max Supply Pressure: 250 psig [17 BAR]
Max Output Pressure: 150 psig [10 BAR]
Flow Capacity: 150 SCFM (255 m3/HR)
Accuracy: 0.5 psi (typ)