29Installation, Operations & Maintenance Manual
4.8 RELIEF VALVE POPPET
Milton Roy recommends that the relief valve
poppet be replaced yearly during preventative
maintenance. This can usually be timed to
coincide with check valve replacement. Refer to
the instructions in the “Corrective Maintenance”
section.
4.9 CORRECTIVE MAINTENANCE
4.9.1 Check Valve Cartridge Replacement
With the exception of the mRoy A and L plastic
versions, mRoy suction and discharge check valve
cartridges are precision machined and assembled
at the factory. Do not attempt to disassemble
these cartridges. If they become inoperative, ush
them with Safety Solvent, wash them with warm
detergent and blow them out with compressed air
to remove any foreign matter. (Refer step 4, from
topic section 4.9.1.1). If this treatment does not
eliminate the trouble, the cartridge assembly should
be replaced. mRoy A plastic suction and discharge
check valve cartridges may be disassembled for
cleaning or parts replacement.
4.9.1.1 Metallic Liquid Ends
(Figures 19, 20, 21 & 24)
Disassembly
1. The check valve cartridge assemblies use
a SAE straight thread with an O-ring seal to
facilitate port alignment with the connecting
pipes. To remove the cartridge from the liquid
end, rst loosen the lock nut (520) one or two
threads then unscrew the cartridge.
2. Remove and discard the O-ring (540) and spiral
back-up ring (530).
3. On model MRA High Viscosity pumps only, the
ball in the suction port of the liquid end is not
sealed inside the suction check valve. This ball
should fall out easily when the suction check
valve is removed.
4. Carefully clean any parts to be reused. If any
chemicals are used in the cleaning process,
ensure that they are approved with the process
liquid.
Reassembly
1. To install the cartridge, position the lock nut
(520) toward the shoulder of the cartridge so that
the recess on the face of the lock nut is adjacent
to the O-ring (540) land (thread undercut) in the
cartridge.
2. Make certain the spiral back-up ring (530)
is coiled in a counterclockwise helix (this is
opposite the direction normally employed by
suppliers of these rings. Fit the spiral back-up
ring (530) in the lock nut (520) recess. Push
it rmly down in the recess as completely as
possible.
3. Install a new O-ring (540) against the spiral
back-up ring (530).
NOTE:
To assure a tight, leak free seal, new O-rings
and spiral back-up rings should be used each
time the check valves are disassembled.
4. On model mRoy “V’ option pumps only (Figure
19), the separate ball (570) needs to be balanced
on the end of the suction check valve cartridge
so that it will be held in place in the suction port
by the check valve when it is screwed in.
5. Screw the cartridge assembly into the liquid end
until the O-ring band is approximately level with
the top of the spot face in the liquid end, then
screw it in one (1) additional turn plus a partial
turn as required to align the pipe thread port
with connecting pipe.
SECTION 4 - MAINTENANCE
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