Hale 4DK Series - Manual (Page 45)

Manual p/n: 029-0020-79-0 45
4DK Series Pumps
Positive................ Pressure above atmospheric.
Pressure
Power Valve ........ A valve that uses hydraulic pressure to transfer two-stage pump operation from
volume mode to pressure mode, and vice versa
Pressure .............. Force per unit area.
Pressure .............. The pressure gauge is usually graduated in pounds per square inch (PSI) only. It is
Gauge
connected to the pump discharge manifold, thus indicating pump discharge
pressure.
Priming ................ Priming evacuates the air from the main pump and suction hose, thus creating a
vacuum. This allows atmospheric pressure on the source of the fluid to push the
fluid up into the suction hose and pump.
Priming Pump...... An auxiliary positive displacement pump which pumps air out of the booster pump
that creating a vacuum to prime the main pump. The priming pump is a rotary vane
type, electric motor driven. Once the main pump is primed and pumping, the priming
pump is shut off.
Priming Pump...... A valve located in the priming line between the priming pump and the main pump.
Valve
It remains closed at all times except when priming. The control is normally located
on the pump panel.
Pump Shift ........... A midship pump is usually mounted with a split gearbox installed in the drive shaft.
The pump shift moves a sliding gear in the gearbox that transmits power either to the
pump or the rear axle. In ROAD position, power is shifted to the rear axle for driving;
in PUMP position, the rear axle is disconnected, and power is shifted to the pump
shaft.
Relay ................... Movement of water from an apparatus at a water source to additional apparatus until
water reaches the fire ground.
Relief Valve ......... An automatic valve which, when activated by the relief valve control, will hold pump
pressure steady when discharge valves or shut-off nozzles are closed. The valve
maintains its given pressure by dumping the pump discharge flow into the pump
suction.
Relief Valve ......... A handwheel adjustment valve which controls and/or adjusts the relief valve to
Control (PM)
maintain the working pressure (i.e., set to control the desired pressure).
Series .................. Pressure position in which the first impeller’s discharge is fed to the eye of the
second impeller in a two-stage pump which then discharges the fluid from the pump.
Service Test ........ Pump test performed to determine if the apparatus can deliver its rated volume and
pressure.
Shrouds ............... Sides of an impeller that confine the fluid.
Slinger Ring......... Prevents fluid from continuing to travel down a shaft to the gears and ball bearings.