Brand: Fisher

Fisher 667 Diaphragm Actuator

Name: Fisher 667 Diaphragm Actuator – Datasheet & Price Quote
Brand: Fisher

Description

Overview

The Fisher 667 Diaphragm Actuator is a reverse-acting, spring-opposed pneumatic actuator that Emerson engineers for dependable on/off and throttling control of sliding-stem valves, most commonly angle and globe control valves in continuous process service. Unlike its direct-acting sibling, rising signal pressure on the 667 retracts the actuator stem against the opposing spring, which makes it the natural choice whenever a control loop’s fail-safe philosophy calls for the valve to fail closed on loss of air rather than fail open. This reverse-acting behavior is achieved with the same proven spring-opposed diaphragm mechanism used across the Fisher 600 series, so plants gain fail-safe flexibility without introducing an unfamiliar actuator technology.

With engineering support in Muscat, Seven Star LLC supplies the 667 Diaphragm Actuator to industrial buyers throughout the Sultanate of Oman and the wider GCC, with correct spring and action selection guidance and local technical backing. Process plants in Muscat, Sohar, and across the region depend on this trusted supply channel for actuators carrying valid SIL-capable and safety-instrumented-system documentation.

Operating Principle

In the Fisher 667, increasing pneumatic signal pressure on the diaphragm compresses the opposing range spring while retracting the actuator stem, and falling signal pressure allows the spring to drive the stem back out, reversing the direct-acting behavior of the 657 while sharing the identical diaphragm casing and spring hardware. This reverse-acting arrangement lets instrumentation engineers select fail-open or fail-closed behavior for a given valve simply by specifying a 657 or a 667, rather than needing an entirely different actuator platform for each fail-safe direction.

Like the 657, the 667 uses a molded diaphragm traveling in a deep diaphragm casing to minimize effective area change across the stroke, keeping output thrust consistent from end to end, and a shallow pressure-side casing to reduce internal air volume and shorten dynamic response time. Because the 667 can be externally tubed for instruments or accessories when required, it also accommodates installations where a positioner or transducer must be mounted at a distance from the actuator body, giving engineers layout flexibility that the fully integral 657 configuration does not always allow.

Engineering Design of the Fisher 667

The Fisher 667 shares the 657’s integral mounting pad, which eliminates the traditional separate mounting bracket and reduces the total part count needed to attach the actuator to the valve body, while also carrying an integral air passage that removes external tubing when a Fisher FIELDVUE digital valve controller is fitted directly to the actuator. This shared architecture means plants running both fail-open and fail-closed loops can standardize spare diaphragms, springs, and mounting hardware across their 657 and 667 populations.

Where a project calls for the positioner or FIELDVUE instrument to sit apart from the actuator casing, the 667’s external tubing capability provides the flexibility to route pneumatic signal lines to remotely mounted accessories without modifying the actuator itself. The 667 accepts manual handwheel operators for local override, and its spring-opposed diaphragm construction covers cryogenic, low-temperature, standard-temperature, and high-temperature service, so a single actuator family can be specified consistently across process units with mixed thermal duty.

Key Features

The Fisher 667 delivers the same reliable spring-opposed diaphragm mechanism as the 657, configured for reverse-acting, fail-closed control philosophies.

Reverse-acting operation retracts the stem on rising signal pressure, supporting fail-closed control loop philosophies.
The integral mounting pad eliminates the traditional mounting bracket, reducing the number of parts required to mount the actuator.
An integral air passage removes the need for external tubing and fittings when paired directly with a Fisher FIELDVUE instrument.
The actuator can be externally tubed for instruments or accessories when a remote-mounted positioner configuration is required.
A molded diaphragm traveling in a deep diaphragm casing minimizes area change throughout the stroke for consistent output thrust.
A shallow casing on the pressure side reduces internal air volume, minimizing the actuator’s dynamic response time.
Spring rates, travel stops, and manual operators are available across a wide range to suit nearly any control valve application.
Operating temperature ratings span cryogenic, low-temperature, standard-temperature, and high-temperature service classes.

Industrial Applications

The Fisher 667 Diaphragm Actuator is specified throughout oil and gas processing, petrochemical manufacturing, power generation, and district cooling facilities wherever fail-closed control philosophy is required on globe or angle sliding-stem valves, such as feedwater, fuel gas, or chemical injection services where loss of instrument air must drive the valve shut. Its shared hardware platform with the 657 simplifies spares management for plants running a mix of fail-open and fail-closed control loops.

Backed by manufacturer datasheet documentation, Seven Star LLC distributes the 667 to plant operators and EPC contractors across Oman and the GCC, supporting refinery, petrochemical, and power generation projects in the Sohar and Salalah economic zones as well as commercial and utility developments around Muscat. Buyers sourcing the 667 through Seven Star LLC’s trusted supply channel receive genuine Emerson-manufactured actuators with verified fail-safe action documentation and direct access to our instrumentation division for sizing support.

Technical Specifications

The table below summarizes the primary specifications for the Fisher 667 Diaphragm Actuator.

Parameter	Specification
Model	Fisher 667 Diaphragm Actuator
Actuator Type	Reverse-acting, spring-opposed diaphragm, linear travel
Valve Type	Angle valve, globe valve
Power Source	Pneumatic, with manual operator option
Operating Temperature	Cryogenic, low temperature, standard temperature, high temperature
Mounting	Integral mounting pad with integral air passage; externally tubed option available
Compatible Instruments	Fisher FIELDVUE digital valve controllers; traditional bracket-mounted positioners
Sizing Options	Multiple spring rates, travel stops, and manual operators available
Other Configurations	Contact Seven Star LLC for additional specifications or options

Request a Quote for Fisher 667 Diaphragm Actuator

Seven Star LLC invites process engineers and procurement teams across Oman and the GCC to submit a formal RFQ for the Fisher 667 Diaphragm Actuator. Working closely with plant engineers in the region, Seven Star LLC supplies on request with lead time confirmed at quotation, provides full technical datasheets on request, and connects buyers directly with our instrumentation division for fail-safe action selection and FIELDVUE integration support. Contact Seven Star LLC today to request a quotation for Fisher 667 actuators with local engineering support.

Also available: Fisher 1061 Pneumatic Piston Rotary Actuator

See also: Fisher 657 Diaphragm Actuator.

Datasheets & Documents

Datasheet Fisher 667 Diaphragm Actuator Datasheet Download

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About brand

Fisher is the control valve brand of Emerson. Its history starts in 1880 in Marshalltown, Iowa, where William Fisher, working at the town waterworks, invented a constant-pressure pump governor and founded a company to make it. Emerson bought Fisher Controls in 1992, and Marshalltown remains a main engineering and manufacturing site for Fisher valves. The brand covers control valves, actuators, FIELDVUE digital valve controllers, regulators and level controllers.

Seven Star LLC is an independent supplier listing Fisher control valves, actuators, positioners, regulators and spare parts for buyers in Oman and the GCC. Replacement valves and trim are matched from the serial number on the valve nameplate.

Fisher company profile

Origin	William Fisher's constant-pressure pump governor, Marshalltown, Iowa, USA (1880)
Ownership	Owned by Monsanto from 1969; sold to Emerson in 1992 and combined with Rosemount as Fisher-Rosemount, later Emerson Process Management. Today a brand of Emerson.
Main site	Marshalltown, Iowa, USA
Product families	Sliding-stem and rotary control valves, spring-diaphragm and piston actuators, FIELDVUE digital valve controllers, pressure regulators, displacer and digital level controllers
Typical duty	Throttling control of liquids, gas and steam, high-pressure and severe service, instrument supply and gas pressure reduction

Milestones

1880: William Fisher builds a constant-pressure pump governor in Marshalltown, Iowa.
1969: Monsanto acquires Fisher Controls.
1992: Emerson buys Fisher and combines it with Rosemount as Fisher-Rosemount, later Emerson Process Management.

Fisher valves, actuators and instruments

Series	Type	Typical use
easy-e ES, ET, EZ	Sliding-stem globe and angle valves	Cage-guided globe valves: ES with unbalanced plug, ET with balanced trim for higher pressure drop; EZ unbalanced with a seat ring retainer for viscous or dirty fluids
GX	Compact globe valve with integral actuator	Standard chemical and process duty where a compact valve package is preferred
HPT, HPAT	High-pressure globe and angle valves	Pressure classes up to ASME CL2500, compressor recycle and high-pressure letdown
V150, V200, V300, V250	Vee-Ball segmented ball and full-bore ball control valves	High-capacity control of liquids, gas and fibrous or slurry service
CV500	Eccentric rotating plug valve	Erosive, coking and dirty service
8560, 8580	High-performance butterfly valves	Large-line throttling and on-off control
657, 667, 1052, 1061, easy-Drive	Spring-diaphragm, piston and electric actuators	657 and 667 for sliding-stem valves; 1052 and 1061 for rotary valves; easy-Drive where no air is available
FIELDVUE DVC6200, DVC2000, 3610J	Digital valve controllers and positioners	HART positioning with valve diagnostics; 3610J pneumatic positioner for rotary actuators
627, 1098-EGR, 67C	Pressure regulators	Gas pressure reduction, pilot-operated regulation and instrument air supply
DLC3100, 2500	Digital and pneumatic level controllers	Displacer level and interface on separators and scrubbers

Where Fisher valves are used

Fisher control valves and regulators are standard equipment in oil and gas production, refineries, gas processing and LNG, petrochemicals, power plants and water systems. Typical loops are separator level and pressure, compressor anti-surge and recycle, fuel gas pressure reduction, feedwater and steam control, and chemical dosing. FIELDVUE controllers add diagnostics that help plan valve maintenance before a turnaround.

Ordering Fisher valves and spare parts: what we need

For spares, send the serial number from the valve nameplate together with the valve type, size, pressure class, trim and actuator type and size. Emerson keeps the build record behind the serial number, so plug, seat ring, cage, packing and diaphragm kits can be matched without guesswork. For a FIELDVUE or regulator, send the full model and type number and the mounting details. For a new valve add the process data: fluid, flow range, inlet and outlet pressure, temperature, leakage class, fail position, air supply and signal.

Facts checked against Emerson Fisher product information and published company histories, October 2026.

Browse Fisher products by category: Control Valves, Valve Actuator, Valve Positioner, Regulators, Level Transmitter.

FAQ

Questions about the Fisher 667 Diaphragm Actuator

Answers from our engineering team on installation, compatibility and integration.

01How does the Fisher 667 differ from the Fisher 657?

The Fisher 667 is reverse-acting, so rising signal pressure retracts the stem, supporting fail-closed loops, while the Fisher 657 is direct-acting. Both share the same spring-opposed diaphragm hardware and mounting options.

02Can the Fisher 667 be used with a remotely mounted positioner?

Yes. The 667 can be externally tubed for instruments or accessories, giving engineers the flexibility to mount a positioner or FIELDVUE instrument at a distance from the actuator body when the installation requires it.

03What valve types is the Fisher 667 typically used with?

The 667 is most commonly paired with angle valves and globe valves in sliding-stem control valve assemblies across oil and gas, petrochemical, and power generation process units.

04What temperature range does the Fisher 667 support?

The 667 is available in configurations rated for cryogenic, low-temperature, standard-temperature, and high-temperature service, covering a wide span of process operating conditions.

05Is Seven Star LLC an experienced supply partner for Fisher products?

Yes, Seven Star LLC is an experienced supplier of Fisher in Oman and the GCC, supplying Emerson-manufactured actuators, valves, and instrumentation with local technical support.