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Operation
333309E 27
Monitoring the Proportioner
During Operation
When the spray gun is triggered:
• Both A and B fluid pressure gauges should be
increasing and decreasing in pressure at the same
time.
• If one pressure or the other increases while the
other decreases the proportioner is not working cor-
rectly. The cause should be determined and cor-
rected.
• The most typical time for pressure variations to
occur is right after the top change over. This pres-
sure variation is caused by one of the double acting
piston pumps “A” or “B” cavitating during the up, or
fill stroke, and then not having fluid to pump until it
travels down to the filled level. Cavitation causes
ratio errors and should not be allowed at any time
while spraying.
Changing ratios
Remove Pump Lowers
Remove pump lowers as needed (change only the
pump(s) required to achieve the new ratio)
1. Disconnect the suction tube assembly from the
pump inlet.
2. Disconnect the Fluid filter and safety relief valve
assembly from the pump outlet port.
3. Remove coupler nut (24) from connecting rod (36)
using wrench on coupler nut and flats on the con-
necting rod. Do not lose keepers (23 Qty. 2)
required.
4. Remove retaining ring (22) using a spanner wrench
or hammer and punch.
5. Remove pump assembly by lowering out the bottom
of the mounting plate.
Install Replacement Lower for New Ratio
1. Install pump adapter (29) and new pump. Thread
adapter (29) flush with top threaded upper pump
housing. Secure in position by locking in place with
jam ring on pump assembly. See F
IG. 6.
2. Install pump into mounting plate and retain in posi-
tion with lock ring (22) loose fit.
3. Install coupler nut (24) and keepers (23, qty. 2) on
pump displacement rod. Thread coupler nut (24) to
connector rod (36). Tighten and torque to 75-80 lb-ft
(102-108 N•m). If changing to a 25 cc fluid section,
the pump connecting rod (36), keepers (23, qty 2)
and connector nut (24) need to be replaced with the
25cc parts. For the 25cc lower coupler nut (24)
torque to 25-30 lb-ft (31-35 N•m) See Lower
Assembly, page 44.
4. Position pump outlet port fitting for connection to the
relief valve/ fluid filter.
5. Allow pump assembly to center in mounting plate
vertically under connecting rod center line.
6. Torque locking ring (22) to approximately 50 lb/ft
with spanner wrench or hammer and punch while
ensuring pump remains vertical under the yoke to
prevent throat packing side loading when in opera-
tion.
7. Re-connect the safety relief valve, filter, and outlet
hose