Brand: Rotork

Rotork Fairchild Model 81 Multi-Stage Pressure Regulator

Name: Rotork Fairchild Model 81 Multi-Stage Regulator – Datasheet
Brand: Rotork
SKU: Fairchild Model 81

Description

The Rotork Fairchild Model 81 is a precision two-stage pressure regulator. It pairs a pilot control stage with a basic force-balance stage, and Rotork recommends it for highly sensitive instrumentation and control circuits and for equipment that needs high flow together with precise control. The datasheet quotes a sensitivity of less than 0.1 inch water column and a nominal flow of 50 SCFM, while the pilot arrangement keeps air consumption below 0.1 SCFM.

Why a two-stage design

In a single-stage regulator, a large flow demand pulls the outlet pressure down (droop) and a falling demand lets it creep up (boost). The Model 81 uses the pilot stage to drive the main valve so that droop and boost are virtually eliminated, output stays constant over a large flow range, and supply pressure changes have only a minimal effect. A high exhaust capacity reduces the time needed to vent a downstream volume, and a sapphire orifice reduces the abrasive effect of air on the seat.

Technical specifications

Parameter	Specification
Model	Fairchild Model 81 multi-stage pressure regulator (catalog number begins 814)
Flow capacity (nominal)	50 SCFM (85 m3/hr) at 100 psig supply and 20 psig setpoint
Exhaust capacity	5.5 SCFM (9.4 m3/hr) at 5 psig above setpoint
Maximum supply pressure	100 psig on the 0-2 and 0-5 psig ranges; 150 psig on the 20, 60 and 100 psig ranges
Minimum supply pressure	20 psig (1.5 bar)
Maximum output pressure	100 psig (7.0 bar)
Pressure change with supply	Less than 0.2 psig for a 100 psig supply change
Air consumption	Less than 0.1 SCFM (1.7 m3/hr)
Sensitivity	Less than 0.1 inch (0.254 cm) water column
Output ranges (psig)	0-2, 0-5, 0-20, 0.5-60 and 0.5-100
Port size	1/4 inch NPT (BSPT option)
Ambient temperature	-40 to +200 degF (-40 to +93 degC)
Body	Die cast aluminum
Trim	Stainless steel, brass, aluminum and plated steel
Diaphragms	Nitrile on Dacron
Orifice	Sapphire

Catalog options and accessories

The catalog number starts with 814, followed by a range digit (1 for 0-2 psig through 5 for 0.5-100 psig) and the port code 2 for 1/4 inch NPT. Rotork lists these option letters:

E tapped exhaust
P bonnet mounting
T tamper proof
U BSPT tapered threads

A mounting bracket, part 11989, is sold separately, and a service kit is available for the Model 81. Installation, operation and maintenance instructions are published by Fairchild as IS-10000081.

Choosing and confirming

Select the Model 81 where a Model 10 or Model 30 is not sensitive enough, or where a fast-moving load causes visible droop. Check three limits before ordering: the supply pressure must be at least 20 psig and must not exceed the maximum for the chosen range; the setpoint must stay at or below 100 psig; and the port is 1/4 inch only, so larger line sizes need adapters. Confirm the thread type and any bracket or tapped exhaust requirements.

Documents and quotation

The Rotork datasheet is attached to this page. Send Seven Star LLC the catalog number or the range, thread and options you need and we will prepare a quotation from our regulators range. For a single-stage no-bleed alternative see the Rotork Fairchild Model 1000.

Datasheets & Documents

Datasheet Rotork Fairchild Model 81 Multi-Stage Pressure Regulator Datasheet Download

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About brand

Electric valve actuators are what most engineers picture when they hear the name Rotork, a company founded in 1957 and based in Bath, United Kingdom. Its catalog also reaches into pneumatic and hydraulic actuators, control valve actuators and instrument-air accessories.

Seven Star LLC lists Rotork actuators, positioners and precision regulators and supplies them to operators and valve shops in Oman, with the actuator build checked against the manufacturer's documentation.

Rotork product families on this page

The IQ3 is the intelligent multi-turn electric actuator for gate, globe and sluice valves, and the IQT3 is its part-turn counterpart for ball, butterfly and plug valves. For control valves there are the CVA and CMA electric actuators, built for continuous modulating duty. The Skilmatic SI3 is a self-contained electro-hydraulic actuator used where a fail-safe stroke is required. On the fluid power side the page lists GP/GH scotch yoke pneumatic and hydraulic actuators and the CP compact pneumatic quarter-turn unit. Two instrument brands sold under the Rotork name complete the list: Fairchild, with the Model 1000 no-bleed precision regulator, and YTC, with the YT-1000 electro-pneumatic and YT-3300 smart positioners.

Where Rotork actuators are used

Typical duties are isolation and block valves on pipelines and tank farms, motor-operated valves in refineries and power plants, sluice gates and large butterfly valves in water and wastewater works, and emergency shutdown valves on oil and gas facilities across the GCC.

Ordering Rotork actuators and parts: what we need

For an existing unit, send the serial number and the wiring diagram number from the nameplate; these two identify the exact build. For a new selection we need the valve type and size, torque or thrust, stem or shaft details, operating time, supply voltage, phase and frequency, the hazardous area certification, and any bus or remote control option. For pneumatic units add the air supply pressure and the fail position.

Browse Rotork products by category: Valve Positioner, Valve Actuator.