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HEAD OF WATER -- vertical depth of water measured in feet or in pressure per
unit or area. In hydraulics, head always represents pressure and it is
expressed interchangeably in feet of water or pounds per square inch and
sometimes in inches of depth of mercury.
STATIC HEAD -- the pressure that is exerted by a stationary column of water of
a given height or depth.
TOTAL HEAD OR TOTAL DYNAMIC HEAD -- the maximum height above the
source of supply to which the pump would elevate the water plus all the
resistance to flow in the pipe or hose line.
DISCHARGE HEAD -- the pressure measured at the discharge outlet of a pump.
SUCTION HEAD -- the positive pressure measured at the suction entrance of a
pump (when pumping from an elevated tank or hydrant).
VELOCITY HEAD -- the equivalent pressure represented by fluid in motion as
measured by means of a Pitot Gage.
STATIC LIFT -- the vertical height of the center of the pump above the source of
supply (when pump from draft).
TOTAL SUCTION LIFT -- the static lift plus the friction in suction line plus
entrance losses.
NET PUMP PRESSURE -- the total dynamic head of the pump.
EFFECTIVE NOZZLE PRESSURE -- the pump discharge pressure minus hose
friction plus or minus the difference in elevation above or below pump.
WATER HORSEPOWER - the theoretical power required to deliver a given
quantity of water per minute against a given head.
BRAKE HORSEPOWER -- Actual power as delivered by a motor or engine to a
driven machine.
PUMP EFFICIENCY -- The quotient of the water horsepower divided by brake
horsepower required to produce it.
Prepared by: RJG
Approved by: TED
Revised by: TED
DEFINITIONS
Rev. A
Date: 03/04/10
Rev. Date: 30June2015
1200627.doc
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