Hale DSD - Manual (Page 49)

Glossary
G - 2
Gauge Pressure read from a gauge (PSIG).
Pressure
Governor Minimizes pressure changes by controlling engine speed.
Horsepower A measure of mechanical work.
Impeller The working part of a centrifugal pump that, when rotating, imparts energy to water.
Essentially, an impeller consists of two disks separated by curved vanes. The vanes force the
water to move outward between the disks so that it is thrown outward at high velocity by
centrifugal force.
Net Pump The difference in pressure between discharge and suction pressure.
Pressure
Packing Material that maintains an airtight seal at point where the impeller shaft enters and exits
the pump body.
Parallel Capacity position in which each impeller on a two-stage pump works independently into
the discharge.
Pitot Gauge Measures velocity head at the discharge of a nozzle.
Positive A pump with a fixed flow delivered to the discharge with each revolution.
Displacement
Pump
Positive Pressure above atmospheric.
Pressure
Power Valve A valve that uses hydraulic pressure to transfer pump operation from volume to transfer
pressure and vice area.
Pressure Force per unit area.
Pressure The pressure gauge is usually graduated in pounds per square inch only. It is connected
Gauge 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 water to push the water up into the
suction hose and pump.
Priming A positive displacement pump that creates a vacuum to prime the main pump.
Pump
Priming A valve located in the priming line between the priming pump and the main pump. It
Valve remains closed at all times except when priming. The control is located on the
pump panel.