Hale MG - Manual (Page 22)

Muscle Pumps
1-15
Priming Valves
Hale priming valves open when the primer is
operated, to allow the primer to evacuate air in the
pump. There are two priming valves available.
The Hale Semi-Automatic Priming Valve (SPV)
can be mounted directly to the priming connection
on the midship pump, or can be remotely mounted
using a universal mounting adapter. When the SPV
is installed, a single electric push-button on the
operator’s panel starts the priming pump motor.
When the primer motor starts and produces a
vacuum, the SPV opens. Releasing the push-button
stops the priming pump and the SPV closes.
The Hale PVG Priming Valve is mounted on the
operator’s panel. The PVG is a combination valve
and switch. When the panel handle on the PVG is
pulled out the valve opens and the switch energizes
the primer motor. Pushing the handle de-energizes
the motor and closes the valve.
Pressure Control Devices
Two basic types of pressure control devices are
used with Hale Midship pumps:
q Relief valve system (standard).
q Hale Total Pressure Master Relief Valve
System (optional).
Relief Valve System
The Hale Standard Relief Valve System is shown
in figure 1-15. The relief valve system consists of a
panel mounted control valve (PM) and an internal
relief valve, either a QG as shown or a QD.
The relief valve system works as follows: The
strainer mounted in the pump discharge pressure
tap provides pressure to the diaphragm in the PM
Control Valve. The handwheel on the PM control
either increases or decreases spring tension on the
diaphragm. The seat of the QD or QG relief valve
is kept closed by pump discharge pressure.
As pump pressure increases, more pressure is
applied to the diaphragm in the PM Control Valve.
As the pressure on the diaphragm increases beyond
the set point, the stem will move off it’s seat,
allowing pump pressure to push on the piston in
the relief valve. The pressure on the piston will
cause the relief valve seat to lift allowing excess
discharge pressure to dump back to the pump
suction.
The amber indicator light on the PM control
illuminates when the relief valve is open.