Pulsafeeder PulsaPro 900 EN - Manual (Page 33)

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7.4 Hydraulic Performance Valve (HPV)
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 Hydraulic Makeup Valve (HMV)
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
the proper operating position relative to the pump head dish plate. Since the HPV is
unaffected by the vacuum level in the pump head, 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 intermittently restricted or
closed.
PulsaPro 900
High Performance Valves (HPV) and Hydraulic Makeup Valves (HMV)
are factory preset and require no maintenance provided the oil remains clean. Should the
HPV require removal for cleaning or replacement follow the below procedure.
Figure 15