Hale MG - Manual (Page 24)

Muscle Pumps
1-17
Hale Total Pressure Master (TPM) Relief
Valve System
This system, figure 1-16, includes a sensing valve
connected to the inlet side of the pump that works
in conjunction with a Pressure Master Control on
the pump panel to give complete control over the
entire system. The operating point is set by the
Pressure Master Control. Small changes in pump
pressure are normally handled internally by the
recirculating relief valve (QG). Large changes on
either the inlet or discharge side of the pump are
controlled by dumping excess pressure to the
atmosphere from the discharge side of the pump
through the PG30 Relief Valve.
The Hale TPM Relief Valve System is designed to
automatically relieve excess pump pressure when
operating from draft or positive incoming flows.
The system self-restores to the non-relieving
position when excessive pressure is no longer
present.
The TPM relief valve system is a mechanical
system, consisting of an internal relief valve (QG)
which bypasses water to the suction side of the
pump, an external relief (dump) valve (PG30, wit h
sensing valve attached) to discharge water to the
atmosphere, and a single panel mounted control
valve (PMD) to provide control of pump pressure,
within NFPA required limits, to the pump operator.
The PMD control permits the pump operator to
“set” a desired relief pressure for both internal and
external relief valves. The panel control has an
easy to read and easy to set adjustment with an
approximate indication of pressure setting.