Positive Bias Relay (M15)

The Model 15 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 an output pressure that represents the input signal pressure plus a preset bias. Mathematically Po = Ps + K where Po is output pressure, Ps is signal pressure and K is the spring constant. This unit, available in several bias range configurations to meet a variety of output requirements, offers excellent sensitivity and high flow capacity in a small volume. The Fairchild Model 15 Pneumatic Biasing Relay is well suited to a variety of control applications, including range shifting, and tension control, and pressure control from a remote location.


  • Sensitive to 1/4" Water Column variation
  • Balanced Supply Valve
  • Aspirator Tube
  • Flow Capacity of 40 SCFM (68 m3/HR)
  • Separate Control Chamber
  • Mounting Bracket available


  • Permits use in high precision applications
  • Minimises the effects of supply pressure variation
  • Minimises downstream pressure droop under flow conditions
  • Allows use in applications requiring high flow and/or fast response
  • Isolates the diaphragm from the main flow, eliminating hunting and buzzing
  • Quick and easy field installation

See PUB103-065 for further information.

Positive Bias Relay (M15)