Hale MBP Booster - Manual (Page 25)

❑ Introduction
24 Silencer Series Booster Pump, p/n: 029-0020-83-0
The valve is mounted in the discharge piping and plumbed back to the
pump suction. Valve connections are either flanged or Victaulic ™ . (See Fig-
ure 2-10: “P Series Relief Valve System Arrangement,” on page 23.)
How the Relief System Works
A pressure line mounted in the pump discharge pressure tap provides pres-
sure to the diaphragm in the PM control valve. The handwheel on the PM
control either increases or decreases the spring tension on the diaphragm.
The seat of the P series relief valve is kept closed by pump discharge pres-
sure. Also see Figure 2-10: “P Series Relief Valve System Arrangement” on
page 23.
As the 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
moves off its seat, allowing pump pressure to push on the piston in the relief
valve. This causes the relief valve seat to lift, allowing excess pressure to
dump back to the pump suction side.
After the pressure equalizes, the piston returns to the closed position as the
pressure in the relief valve bleeds off through an orifice.
An Amber indicator light on the PM control illuminates when the relief valve
is OPEN.
Thermal Relief Valve (TRV)
The Thermal Relief Valve
protects the pump from over-
heating. (See Figure 2-11:
“Thermal Relief Valve, TRV.”)
The optional TRV unit is
attached to the discharge pip-
ing either by flange mounting
or 1-1/4” NPT threaded con-
nection (38mm for the Model
TRVM).
The valve monitors the tem-
perature of the water in the
pump. When the tempera-
ture exceeds 120°F (48.9°C),
the valve automatically opens
and depending on the instal-
lation, discharges a small amount of water either to the ground or into the
water tank allowing cooler water to enter.
Figure 2-11: Thermal Relief Valve, TRV