Model 25 Reversing Relay

Brand: Fairchild Industrial Products

The Rotork Fairchild Model 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 Model 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 Model 25 is PO = K - PS where PO is output pressure, PS is signal pressure and K is the spring constant.
Features
  • Control Sensitivity of 1/8" water column
  • Balanced supply valve
  • Aspirator tube design
  • Separate control chamber isolates
  • Unit construction
  • Allows for use in high precision applications
  • Minimizes the effects of supply pressure variation
  • Compensates for output pressure droop under flow conditions
  • Isolates the diaphragm from the main flow to eliminate hunting and buzzing
  • Allows servicing without removal from air line

Specifications

Actuator Type

  • Knob Adjust

Ambient Temperature Range

  • -40° to 93° C (-40° to 200° F)

BSP Connection

  • BSPP Female (Parallel)
  • BSPT Female (Tapered)

Elastomers

  • Buna-N on Dacron
  • Fluorocarbon (Viton)

Enclosure, Body Material

  • Aluminum

Exhaust Capacity - Relieving Units Only

  • 11 scfm (18.7 m³/hour)

Flow Capacity

  • 40 scfm (68 m³/hour)

Mounting

  • Panel Mount
  • Pipe

NPT Connection

  • 1/2” NPT Female
  • 1/4” NPT Female
  • 3/8” NPT Female

Pressure Range

  • bar: 0 to 0.7
  • bar: 0.03 to 2
  • bar: 0.1 to 4
  • bar: 0.15 to 10
  • kPa: 0 to 70
  • kPa: 10 to 400
  • kPa: 15 to 1,000
  • kPa: 3 to 200
  • psi: 0.5 to 30
  • psig: 1 to 60
  • psig: 2 to 150

Relief

  • Relieving

Sensitivity

  • < 1/8” WC (0.32 cm)

Signal or Output Pressure - Maximum

  • bar: 10
  • kPa: 1,000
  • psig: 150

Supply Pressure - Maximum

  • bar: 17
  • kPa: 1,700
  • psig: 250

Supply Pressure Effect

  • psig: 0.1 (bar: 0.007, kPa: 0.7) for a psig: 100 (bar: 7, kPa: 700) Change in Supply Pressure

Vent

  • Straight
  • Tapped Exhaust
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