Ralston Instruments DPPV, Operation Manual

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When the Pumping Piston is pumped, pressure does
not increase
If when the Pumping Piston is pumped, pressure does not increase,
then the Vacuum Check Valve is not functioning properly. Follow these
instructions to replace the Vacuum Check Valve (See Section A-A on
page 8 for reference):
1. Remove the Pumping Piston.
2. Remove the Vacuum Check Valve.
3. Clean and lubricate the Vacuum Check Valve.
4. Reinstall the Vacuum Check Valve.
Vacuum Mode
The pump will pull a vacuum, but vacuum slowly
decreases
If the pump will pull a vacuum, but vacuum slowly decreases, then there is
an external leak. Follow these instructions to locate and repair the leak:
1. Connect the pump to a Device Under Test (DUT) with a Ralston
Quick-test™ hose.
2. Make sure the process connections are assembled wrench-tight.
3. Pull a vacuum with the Hand Pump.
4. Spray soapy water or leak detection fluid where leaks are suspected.
5. Observe where bubbles are getting sucked into the pump to deter-
mine where there is a leak.
6. Remove the leaking part and remove the O-ring.
7. Clean and lubricate the O-ring.
8. Replace the O-ring and reassemble.
Vacuum decreases when pumping piston returns to pump
If the vacuum decreases when pumping piston returns to pump, then the
Vacuum Check Valve is not functioning properly. Follow these instruc-
tions to replace the Vacuum Check Valve (See Section A-A on page 8
for reference):
1. Remove the Pumping Piston.
2. Remove the Vacuum Check Valve.
3. Clean and lubricate the Vacuum Check Valve.
4. Reinstall the Vacuum Check Valve.
5. Reinstall the Pumping Piston.