Hale 4DK Series - Manual (Page 44)

44 Manual p/n: 029-0020-79-0
4DK Series Pumps
WARNING !
IF A PUMP IS OPERATED WITHOUT WATER FOR EXTENDED PERIODS,
OR WITHOUT DISCHARGING WATER, IT MAY OVERHEAT. THIS COULD
DAMAGE THE MECHANICAL SEAL OR THE DRIVE MECHANISM.
Double Suction .... Fluid enters on both sides of the impeller.
Impeller
Dry Prime Test .... Provides information on the ability of a priming pump to evacuate air from the main
pump. If the vacuum does not hold, it is an indication there is a leak in the system.
Eye, Impeller ....... Point where fluid enters the impeller.
Flow Meter .......... Measures the volume of fluid that is flowing.
Friction Loss ........ Loss of pressure in hose, fittings, standpipes, and other appliances because of the
resistance between the fluid molecules and the inside surfaces of the hoses, fittings,
standpipes, piping, and other appliances.
Front-Mount ........ Pump mounted ahead of the vehicle’s engine – usually on the front of the radiator.
Pump
Gauge ................. Pressure read from a gauge (PSIG).
Pressure
Governor ............. Minimizes pressure changes by controlling engine speed to maintain pump
discharge pressure.
Horsepower ......... A measure of mechanical work.
Impeller ............... The working part of a centrifugal pump that, when rotating, imparts energy to fluid.
Essentially, an impeller consists of two disks separated by vanes. The vanes force
the fluid to move outward between the disks so that it is thrown outward at high
velocity by centrifugal force. The water from the impeller discharges into a diverging
passage known as a volute, converting the high velocity energy of the water into
pressure.
Net Pump ............ The difference in pressure between discharge and suction pressure.
Pressure
Packing ............... Material that maintains an airtight seal at the 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 – often termed "Volume Mode."
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