Glossary

(GPM)

Gallons Per Minute.

(GPH)

Gallons Per Hour.

(GPD)

Gallons Per Day.

(M3/hr)

Meters cubed per hour.

Total Dynamic Head (TDH)

The sum of discharge head plus suction lift or minus suction head.

Specific Gravity (SG)

The Density of a liquid as compared to water at a given temperature. Water is used as the standard at 14.7 psia at 60°F. Its specific gravity is 1.0 at this standard temperature.

NPSHa

Net positive suction head available is the term for providing sufficient pressure on the pump suction to prevent boiling. [See Cavitation]

NPSHr

Net positive suction head required by a pump. All pumps have a suction head requirement. The NPSHa needs to be greater than the NPSHr to prevent cavitation.

Viscosity

The measure of a fluids resistance to flow under an applied force at a given temperature. Viscosity can be thought as the "Thickness" of a liquid.

Cavitation

Occurs when vapor bubbles form in the eye of the impeller. As the flow moves outward in the impeller waterways, the pressure increases above the vapor pressure and the vapor bubbles collapse causing the pump to sound as if gravel is running through it.

Vapor Pressure (VP)

The amount of pressure required to prevent a liquid from boiling. As the temperature increases the vapor pressure increases.

pH

A symbol for measuring the Acidity or Alkalinity of liquid solutions.

Specific Heat

Amount of energy required to change a given amount of product up 1 degrees.

Differential Pressure

Discharge pressure minus suction pressure.

Shear Sensitive

Does the pump need to have a gentle pumping action to prevent product degredation?

Dilatant

Fluid viscosity increases as shear rate increases.

Thixotropic

Fluid viscosity decreases with time under shear conditions.

NIPA

Net inlet pressure available.

Centrifugal Pumps

Is classified as a machine that converts velocity energy into pressure or hydraulic energy through centrifugal action. Centrifugal pumps are generally used for fluids that are less than 200 centipoise viscosity.

Positive Displacement Pump

The area or volume inside the pump is displaced with each revolution of the pump shaft and the pressure capability of the pump is a result of the down stream system resistance.