M25/M50 Series - FW Murphy Production ControlsFW Murphy Production Controls

Electromechanical Valves for Fuel Gas Shutoff

These fuel shutoff valves are semi-automatic devices for shutdown of natural gas-fueled engines.

Instant response to shut-off signal
Positive valve closure
Vents gases trapped after shutdown
Explosion-proof models available
Models available for magneto, CD ignition or 12/24 VDC
Normally energized model available

FW Murphy Production Controls offers support for all our products. If you are unable to find the product that you need, please call us at 918-957-1000.

The valve is opened manually and closes when the electromagnet is energized and trips the latch. The valve can be closed manually by turning the disconnect knob. A normally energized model is available that holds the valve open electrically and closes when the coil is de-energized. A vent in the valve body relieves trapped gas when the valve closes. A pop-out indicator button informs you when the valve is open or closed.

The valve’s tripping power is provided by an engine ignition system or battery. Models are available for magneto, CD ignition or 12-/24-V battery.

The M2582 is a 1-in. (25 mm) valve with one NPT connection. It has one SPDT snap-switch. The valve body is made of sandcast aluminum. It does not include the open/close indicator button.

The M5081 is a 2-in.h (51 mm) valve with two NPT connections. It has two SPDT snap-switches. The valve body is available in sandcast aluminum or cast steel (optional).

The M5081FS is the same as the M5081 but has a normally energized circuit. This circuit allows the valve to be held open electrically and close by interruption of the coil’s power circuit. A manual disconnect/trip knob is not available on this model.

Options and Accessories

Magnetic Switch Adapter
As ignition systems wear from usage, their power output becomes less and less. Ignition may not have the capacity to reliably trip the fuel valve. Therefore, the use of a Magnetic Switch Adapter for CD ignition systems is recommended. The adapter stores energy from the CD ignition to trip the fuel valve.

Two Magnetic Switch Adapter models are available:

65700053 (65020126): For Negative Ground CD Ignitions up to 240 VDC maximum
65700055 (65020155): For Negative Ground CD Ignitions 240 VDC to 450 VDC maximum

Valve Body:
- Sandcast aluminum, painted red (corrosion resistance)
- Optional cast steel available for M5081 and M5081FS models only
Valve Seat: Buna-N
Maximum Pressure Rating:
- M2582: 80 psig (552 kPa) [5.52 bar]
- M5081: 100 psig (689 kPa) [6.89 bar]
- M5081FS: 100 psig (689 kPa) [6.89 bar]
Coil Rating: Intermittent duty; coil type must match power source
- CD ignition coil resistance: 72 Ω
- CD primary voltage current: 1.38 to 3.8 A
- M5081FS model: Energized to run (continuous-duty coil) coil resistance:
  - 24 Volt model: 136 Ω (0.17 A)
  - Magneto ignition coil resistance: 0.5 Ω
  - Magneto primary voltage current: 1 to 5 A
  - Battery coil resistance: 7 Ω
    - 24 VDC: 1.2 to 2.4 A
Wiring (See Internal Wiring):
- M2582: Wire leads
- M5081 and M5081FS: Terminal blocks
Snap-switch Rating: 5 A @ 480 VAC
Laboratory Approval: CSA listed for Class I, Groups C and D Hazardous Locations. 5 amps maximum; intermittent duty; models M5081 and M5081-CD engine ignition powered and model M5081-B, 24 VAC or VDC; switch contacts rated 5 A @ 480 VAC maximum

M2582 Dimensions

M5081 / M5081FS Dimensions

M2582 Flow Rate

M5081 / M5081FS Flow Rate

M2582 Internal Wiring

NOTE: An FW Murphy Magnetic Switch adapter must be used in addition to a 100-ohm, 2-watt resistor, for grounding the ignition (CD ignition models only) through the fuel valve’s internal snap-switch.

M5081 Internal Wiring

M5081FS Internal Wiring

For more information about this product, you can download the related literature here:

Sales Bulletin (94134; revision date: 04/2024)

Installation Instructions (00-02-0206; revision date: 04/2024)

M50/M25 Topworks Kit Instructions (00-02-0635; revision date: 03/2016)