Pulsafeeder Pulsar Shadow - Manual (Page 27)

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7.4 Hydraulic Performance Valve (HPV)
7.4.1 General Description
During normal pump operation hydraulic fluid is continually discharged through the automatic bleed
valve and may also be lost past the piston seals. This causes the diaphragm to be drawn further back on
each successive suction stroke until it actuates the HPV. Once the valve is actuated, oil is allowed to
flow into the hydraulic system until the piston reaches the end of the suction stroke. As the piston starts
forward a check valve prevents oil from flowing back through the HPV, thereby allowing the valve to
close as the diaphragm moves forward. Through this process the diaphragm is continually maintained
in a proper operating position relative to the pumphead dish-plate. Since the HPV is unaffected by the
vacuum level in the pumphead, oil cannot be inadvertently brought into the hydraulic system which
would result in over-extension and damage to the diaphragm. This feature provides pump protection
should the suction line become restricted or closed.
PULSAR pumps utilize two styles of High Performance Valves (refer to Figure 17) dependent on the
pumphead size. Although different in appearance they function identically. The valves are factory
preset and require no maintenance provided the hydraulic oil remains clean. The check valve in series
with the HPV includes a screen to trap contaminants (refer to Figure 15) and should be removed and
cleaned with each change of the hydraulic oil as indicated below. A clogged filter screen will impede
the operation of the HPV, and can lead to diaphragm damage. Should the HPV require removal for
cleaning or replacement, follow the procedure appropriate to the valve style. If a diaphragm has failed,
and chemical has contaminated the pump head assembly, both the HPV and the HPV check should be
removed and thoroughly cleaned.
Figure 17
7.4.2 Check Valve Screen - Removal and Cleaning
Use the following procedure to remove and clean the Check Valve screen (refer to Figure 15) It is
easiest to perform this process during an oil change:
1. Disconnect the power source to the drive motor
2. Relieve all pressure from the piping system.
3. Drain hydraulic fluid from the eccentric box.
4. Unscrew the check valve from the bottom of pump head.
5. Clean the valve and screen in a solvent compatible with the nitrile seal material and blow air through
the valve to remove all contaminants.
6. Inspect the copper gasket and o-ring for nicks or other damage and replace if necessary.
7. Lubricate the o-ring with PULSAlube 7H and replace the valve, tightening securely.
8. Re-install the eccentric box drain plug and refill with PULSAlube 7H hydraulic oil.