The Fairchild 25 Reversing Relay provides and output which will decrease in direct proportion to an increase in input pressure. The Model 25 is ideally suited for a variety of precision control applications, including converting direct acting valves to recerse action, controlling opposite acting valves from a single transmitter, and cushioning cylinder loads.
The Fairchild 25 Reversing Relay is designed for applications requiring an output that equals a manually preset spring load minus a variable signal pressure. This high quality unit combines excellent sensitivity with unusually high flow capacity.
The Fairchild 25 is ideally suited for a variety of precision control applications, including converting direct acting valves to reverse action, controlling opposite acting valves from a single transmitter, and cushioning cylinder loads.
The basic mathematical expression for the Fairchild 25 is PO = K - PS where PO is output pressure, PS is signal pressure and K is the spring constant.
Maximum Supply Pressure
250 psig, [17.5 BAR], (1750 kPa)
40 SCFM (68 m³/HR) @ 100 psig, [7.0 BAR], (700 kPa) supply, 20 psig, [1.5 BAR], (150 kPa) setpoint
11 SCFM (18.7 m³/HR) where downstream pressure is 5 psig, [.35 BAR], (35 kPa) above setpoint
Signal or Output Pressure
150 psig, [10 BAR], (1000 kPa) maximum
Supply Pressure Effect
Less than 0.1 psig, [.007 BAR], (.7 kPa) for 100 psig, [7.0 BAR], (700 kPa) change in supply pressure
Less than 1/8” (.32 cm) Water Column
Pipe or Panel
Ambient Temperature Limits
-40°F to +200°F, (-40°C to 93.3°C)
Materials of Construction
Trim: Aluminum, Stainless Steel, Brass
Diaphragms: Buna N and Dacron