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M25 and M50 Series
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Instant Response to Shut Off Signal
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Positive Valve Closure
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Vents Gases Trapped After Shutdown
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Explosion-proof Models Available
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Models Available for Magneto,
CD Ignition or 12/24 VDC
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Normally Energized Model Available
Description
These fuel shutoff valves are semi-automatic
devices for shutdown of natural gas fueled
engines. 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 valve’s disconnect knob. A normally energized
model is available that holds the valve open elec-
trically 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 avail-
able for magneto, CD ignition or 12/24 V battery.
The M2582 is a 1 inch (25 mm) valve with 1
NPT connections. It has one SPDT snap-switch.
The valve body is made of sandcast aluminum. It
does not include the open/close indicator button.
M5081 is a 2 inch (51 mm) valve with 2 NPT
connections. It has two SPDT snap-switches.
The valve body is available in sandcast alu-
minum or cast steel (optional).
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 trip knob is not available on this model.
An optional 2 in. (51 mm) steel flange pipe con-
nection is available for M5081 and M5081FS
steel body models (see Dimensions page 3).
Specifications
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: 1.38 to 3.8 A
• M5081FS model: Energized to run
(continuous-duty coil) coil resistance:
12 Volt model: 33 Ω (0.36 A)
24 Volt model: 136 Ω (0.17 A)
• Magneto ignition coil resistance: 0.5 Ω
• Magneto primary voltage: 1 to 5 A
• Battery coil resistance : 7 Ω
12 or 24 VDC: 1.2 to 2.4 A
Wiring (See Internal Wiring page 2):
• 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, 12 or 24 VAC or VDC; switch con-
tacts rated 5 A @ 480 VAC maximum.
Options and Accessories
Diode Package (65010065)
The Murphy 202 V diode package is designed to
allow the fuel shutoff valve to be used with dual
Magneto Ignition systems. Sold separately (see
How to Order).
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. Three models are available:
65020126: For Negative Ground CD Ignitions
up to 240 VDC
65020127: For Positive Ground CD Ignitions up
to 450 VDC
65020155: For Negative Ground CD Ignitions
240 VDC to 450 VDC
Warranty
A limited warranty on materials and workmanship
is given with this FW Murphy product. A copy of
the warranty may be viewed or printed by going to
www.fwmurphy.com/support/warranty.htm
Model M5081
MV-94134B
Revised 07-99
Catalog Section 55
(00-02-0124)
Electromechanical
Fuel Shutoff Valves