Specifications

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Spray Valve Maintenance
Valve Reassembly
1. Place the new diaphragm over the threaded
end of the needle. The black Viton side of
the diaphragm should face the threaded
end. The blue-grey Teflon side should face
the wetted side of the valve. Note illustration
on page 23.
2. Place the spring locating washer over
threaded end of the needle. The stepped
side should face the threaded end.
3. Install a new diaphragm retaining nut
(included with #7021727 diaphragm) and
turn it until the nut starts to feel tight and
the diaphragm cannot be rotated on the
needle with fingers. Avoid crushing the
diaphragm causing it to bulge away from
the washer.
4. Install the needle/diaphragm assembly into
the valve body, then install diaphragm return
spring and diaphragm chamber cap, and
tighten firmly.
5. Reinstall the nozzle, air cap and air cap
retainer.
The air cap retainer nut should be
tightened with a wrench to prevent
loosening due to press vibration.
22 Spray Valve Maintenance
WARNING: Before performing
any maintenance, set the
System Pressure Switch to the
Off position and depressurize the
tank reservoir by lifting the lever
on the tank pressure relief valve.
When using filtered plant air and clean lubri-
cants, the MC785M series spray valves are
designed for long- term performance without
scheduled maintenance.
If lubricant flow stops or becomes erratic, first
review Troubleshooting on page 26. Cleaning
the nozzle will solve most problems related to
lubricant flow and spray patterns.
To Clean the Nozzle
Remove the air cap retainer nut, air cap and
nozzle from the outlet end of the valve. Clean
and reinstall.
Valve Disassembly
Note: Install a new diaphragm (#7021727)
each time the valve is reassembled.
1. Remove air cap retainer nut, air cap and
nozzle from the outlet end of valve.
2. Remove diaphragm chamber cap,
diaphragm return spring and
needle/diaphragm assembly from the valve
body.
3. Remove diaphragm retaining nut and spring
locating washer from the needle, then
remove and discard old diaphragm.
4. Clean all parts in mineral spirits.