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Glossary of pump terms: N

Negative pressure: In reference to one atmosphere. Anything less than this number is negative.

Newton: The SI derived unit of force. Because force equals mass times acceleration, the Newton is equal to 1 kg *m/s².

Newtonian fluid: A fluid that behaves without changing its viscosity as a function the rate of flow.

Non-destructive examinations (NDE): A process which pumps or pump components are examined for defects without resulting in the destruction of the component being examined aka non-destructive testing (NDT).

Non lubricant: In contrast to a lubricant, this type of fluid does not act to reduce friction of moving parts against each other.

Non-Newtonian liquid: In contrast to a Newtonian fluid, this type of fluid has a viscosity that changes as a function of flow rate, or shear stress.

Normal operating point: This is the set of conditions at which the pump normally operates. It could be the same or different than the best efficiency point or the rated operating point.

Nozzle head: The part of a pump where the fluid is discharged. Commonly reduced diameter causes the fluid to exit the system faster than its flow through the system.

NPSH_A: The net positive suction head available that can be used to prevent cavitation within the pump. It is defined as static head plus surface pressure head minus the vapour pressure of the process fluid minus the friction loss due to the piping, valves and fittings.

NPSH_R: Net positive suction head required to keep a pump from cavitating. A characteristic of the pump. Calculated by the manufacturer with cold water.

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