Universal Pump Service Manual
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6. Remove the top pulsation dampener assembly and repeat Steps 3 and 4. If there is no movement, replace the top
pulsation dampener assembly and repeat Steps 3 and 4. If there is still movement in the water column, see Step 7.
7. Replace the regulator with a new one and repeat Steps 3 and 4.
Throughout this procedure, simply replace the last part removed before the leak went away.
8. Reassemble the stack and retest the pump for leaks (s
ee Functional Testing, Initial Leak Check
).
9. Set fl ow compensation and set regulator (
See Pump Reassembly, Se! ing the Flow Compensation and Pump Disassembly,
Se! ing the Regulator
).
Bo om Half Stack Leak Check
Remove the motor/eccentric assembly from the pump housing (
see Pump Disassembly, Disassembling the Stack, Steps 5
and 6).
Because it is very diffi
cult to determine the source of leaks in the bo# om half stack, SKC recommends complete
replacement with Cat No. P21251
(does not include a pressure switch assembly)
. A$ er replacing the half stack with a new
one, perform functional testing (
see Functional Testing).
Set fl ow compensation
(see Pump Reassembly, Se! ing the Flow
Compensation).
Checking Pumping Operation
If the pump failed the fl ow range compensation testing during functional testing but does not show signs of a leak,
there could be a problem with the valves. Before checking the valves, ensure that the two stack halves are assembled
and that the motor/eccentric assembly is removed from the pump housing (
see Pump Disassembly, Disassembling the Stack,
Steps 5 and 6
).
1. With the stack assembled but the motor/eccentric assembly removed, a# ach the stack (regulator) inlet to a water
manometer (Figure 6).
2. Using a fi nger, gently push the yoke/diaphragm in the pump housing up and down and observe the water column
on the manometer. The column should rise evenly and steadily with each stroke. If it does not, there is a leaky
valve.
3. Apply vacuum pressure and observe the yoke/diaphragm assembly for movement. The yoke will move toward
the leaking inlet valve.
4. Ensure that the pump exhaust port fi # ing (Figure 1, #22) is installed on the exhaust port and a# ach the pump
exhaust port to the water manometer.
5. Apply positive pressure and observe the yoke diaphragm assembly for movement. The yoke will now move away
from the leaking outlet valve.
6. Replace the leaking valve plate assembly (
see Pump Disassembly and Pump Reassembly
) and retest the pump for
leaks (
see Functional Testing, Initial Leak Check).
If the yoke/diaphragm does not move either way, it could mean that both inlet valves are leaky. Perform a visual check
for wrinkled valves or dust under the valves. Replace the entire valve plate if necessary.
Setting the Regulator
This is only required if the low fl ow mode is used frequently or non-factory repairs have been made. Check the pressure
regulator periodically during routine maintenance to assure pump accuracy. The pressure regulator is factory preset to
20 inches water back pressure at 1500 ml/min.
To perform the following steps the ba# ery pack and back pump case must be removed and the stack partially
disassembled (
see Pump Disassembly, Disassembling the Stack, Steps 1 and 2).
In newer pump models, the 1-1/8 x 1-1/4-inch plate on the top of the pump may need to be removed to
access the regulator adjustment screw. This may be done by removing the back cover of the pump. Be
careful not to bind internal parts and wires.
1. Remove both cap screws from the top of the pump (Figure 1, #15 and 16). Li$ the stack out of the case and remove
the brown plate from the top of the stack.
