Hale RSD - Manual (Page 109)

G lo ss ar y a nd M ea su r em en ts
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109
Appendix A: Glossary / Measurements
Hale Products, Inc., Nov. 2005, Rev.-A
Pitot Gauge.........Measures velocity head at the discharge of a nozzle and can be converted to flow using
a chart or simple calculation.
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 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
Gauge
is connected to the pump discharge manifold, thus indicating pump discharge ressure.
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
creates 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, holds 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.