Images are representations only.

Model 85D Multi-Stage Positive Bias Relay

Brand: Fairchild Industrial Products
The Rotork Fairchild Model 85D Multi-Stage Biasing Relay is a precision control combining the sensitivity of a precision pressure regulator with positive biasing capability. 

This compact, pilot-operated device offers unusually high output capacity with minimal air consumption, while providing excellent protection against supply or output pressure variations.

The versatile Model 85D is recommended for use in systems requiring precision pressure maintenance and instrument biasing, in dead end service and instrument panel supply applications.

The basic mathematical expression for the Fairchild Model 85D is PO = PS + K where PO is output pressure, PS is signal pressure and K is the spring constant.
Features
  • Two Stage Pilot Operation
  • 14 SCFM flow capacity in a small size unit
  • Low air consumption
  • Compact size
  • Available in 1/8", 1/4" and 3/8" standard port sizes
show more
The Rotork Fairchild Model 85D Multi-Stage Biasing Relay is a precision control combining the sensitivity of a precision pressure regulator with positive biasing capability. 

This compact, pilot-operated device offers unusually high output capacity with minimal air consumption, while providing excellent protection against supply or output pressure variations.

The versatile Model 85D is recommended for use in systems requiring precision pressure maintenance and instrument biasing, in dead end service and instrument panel supply applications.

The basic mathematical expression for the Fairchild Model 85D is PO = PS + K where PO is output pressure, PS is signal pressure and K is the spring constant.
Features
  • Two Stage Pilot Operation
  • 14 SCFM flow capacity in a small size unit
  • Low air consumption
  • Compact size
  • Available in 1/8", 1/4" and 3/8" standard port sizes
Close
Close

Specifications

Brand

Signal or Output Pressure - Maximum

  • psig: 150 (kPa: 1,000, bar: 10)

Ambient Temperature Range

  • -40° to 93.3° C (-40° to 200° F)

Supply Pressure

  • psig: 150 (kPa: 1,000, bar: 10) Recommended Operating Supply Pressure

Standard Features

  • Tamper-Proof

Air Consumption

  • < 0.1 scfm (0.17 m³/hour)

Exhaust Port

  • Tapped Exhaust

Supply Pressure Effect

  • Less than psig: 0.2 (bar: 0.0014, kPa: 1.4) for psig: 100 (bar: 7, kPa: 700) Change in Supply Pressure

NPT Connection

  • 1/4" NPT Female
  • 1/8" NPT Female
  • 3/8" NPT Female

Pressure Range

  • bar: 0 to 7
  • kPa: 0 to 700
  • psig: 0 to 100

Diaphragm Material

  • Buna-N & Dacron

Flow Capacity

  • 14 scfm (23.8 m³/hour)

Enclosure, Body Material

  • Aluminum

Trim Material

  • Aluminum
  • Brass
  • Stainless Steel

Exhaust Capacity - Relieving Units Only

  • 2.5 scfm (4.25 m³/hour) where Downstream Pressure is 5 psig (bar: 0.35, kPa: 35) Above Set Point

BSP Connection

  • 1/4" BSPT Female
  • 1/8" BSPT Female
  • 3/8" BSPT Female

Mounting

  • Bonnet Mounting

Supply Pressure - Maximum

  • bar: 17.5
  • kPa: 1,750
  • psig: 250
Close