“MP-2”
MANUAL RELAY
MODEL 10A1
OPERATION MANUAL
OMP # 10A1 12/00
I. PRINCIPLE OF OPERATION
The Ruelco “MP-2” relay is a pilot operated
manual relay. It is a three (3) way, normally
closed valve with a palm knob for relay
position indication and manual operation. In
the closed position, pneumatic or hydraulic
pressure coming into the “Inlet” port is
locked from the “Outlet” port by the upper
shaft o-ring. The spring keeps the spool in
the down or closed position. The valve is
opened by manually pulling the palm knob
outward, thus moving the shaft assembly
upward. The detent pin is then pushed “In”
to lock the relay open until a pneumatic
signal is applied to the pilot cap of the relay.
This pneumatic pressure acting on the
piston causes the detent pin to drop “Out” of
the locked position. When the relay is in the
open position, it causes the middle o-ring to
engage the body seal bore and the upper o-
ring to disengage from the body seal bore
respectively. Supply pressure at the “Inlet”
port may then flow through the body to the
“Outlet” port.
When the pneumatic signal is removed from
the pilot cap, the spring moves the shaft
assembly downward. This causes the upper
o-ring to engage the body seal bore and the
middle o-ring to disengage the body seal
bore respectively. With the supply pressure
blocked, pressure will flow from the “Outlet”
port and exit through the “Vent” port. The
relay may also be closed manually by
pushing the palm knob inward.
II. INSTALLATION
The “MP-2” can be mounted either
vertically, horizontally, panel mounted (with
optional panel mount nut), or supported by
piping from any of its ports. If it is supported
by piping, care should be taken that the
strength of the pipe fittings used is adequate
to prevent the fitting from breaking off in the
relay body should the relay be inadvertently
struck.
Proper pipe thread sealant should be used
on any pipe fittings threaded into the relay
ports. If stainless steel fittings are used, a
sealant that will prevent galling is required.
Supply gas or hydraulic fluid flowing through
the relay should be free of large dirt
particles. If compressed air is used, it does
not have to be lubricated. If natural gas is
used, it should contain as little condensate
as possible. This will extend the life of the
seals.
If the relay is going to be installed in a
location where the stem will be exposed to
excessive paint, sand, drilling fluids, etc.,
the use of the optional stem protector is
recommended. The stem protector does not
affect the operation of the relay and will
prevent the relay from jamming should the
exposed portion of the shaft accumulate
excessive trash or debris.
III. DISASSEMBLY (REFER TO SPEC.
SHEET 10A1)
Tools required are as follows:
•7/16” open end wrench or
suitable adjustable wrench
•1” open end wrench or suitable
adjustable wrench
•7/8” open end wrench or suitable
adjustable wrench and flat blade
screw driver (for removal of
optional stem protector)
•1/8” Allen wrench (for complete
disassembly)
