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Cavitation—Process in which small bubbles
are formed and implode violently; occurs when NPSHa < NPSHr.
Dead Head—The ability of a pump to
continue running without damage when discharge is closed off.
Only recommended for centrifugal pumps.
Density (specific weight of a fluid)—Weight
per unit volume, often expressed as pounds per cubic foot
or grams per cubic centimeter.
Flooded Suction—Liquid flows to pump
inlet from an elevated source by means of gravity. Recommended
for centrifugal pump installations.
Flow—A measure of the liquid volume
capacity of a pump. Given in gallons per hour (GPH), gallons
per minute (GPM), liters per minute (L/min), or milliliters
per minute (mL/min).
Fluids—Include liquids, gases, and
mixtures of liquids, solids, and gases. In this catalog, the
terms fluid and liquid are both used to mean a pure liquid
or a liquid mixed with gases or solids that acts essentially
like a liquid in pumping applications.
Head—A measure of pressure, expressed
in feet of head for centrifugal pumps. Indicates the height
of a column of water being moved by the pump (without friction
losses).
Pressure—The force exerted on the
walls of a tank, pipe, etc., by a liquid. Normally measured
in pounds per square inch (psi).
Prime—Charge of liquid required to
begin pumping action when liquid source is lower than pump.
Held in pump by a foot valve on the intake line or by a valve
or chamber within the pump.
Seals—Devices mounted in the pump
housing and/or on the pump shaft that prevent leakage of liquid
from the pump.
Self-Priming—Pumps that draw liquid
up from below pump inlet (suction lift), as opposed to pumps
requiring flooded suction.
Specific Gravity—The ratio of the
weight of a given volume of liquid to pure water. Pumping
heavy liquids (specific gravity greater than 1.0) will require
more drive horsepower.
Static Discharge Head—Maximum vertical
distance (in feet) from pump to point of discharge with no
flow.
Strainer—A device installed in the
inlet of a pump to prevent foreign particles from damaging
the internal parts.
Sump—A well or pit in which liquids
collect below floor level; sometimes refers to an oil or water
reservoir.
Total Head—Sum of discharge head,
suction lift, and friction loss.
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