Glossary of fluid power principles and components terms N

NAHAD
The abbreviation for the Association for Hose and Accessories Distribution.
 

NATIONAL ELECTRICAL CODE (NEC)
Standards, recommended practices, specifications and directional for electrical wiring of residential, commercial, industrial and farm buildings. Published by the National Fire Prevention Association.

NECKING DOWN
A localized decrease in the cross-sectional area of a hose resulting in tension.

NEEDLE VALVE
A two-way valve that may be opened or closed to block the flow of fluid in a passage. Normally manually operated, but may be automated, especially for larger sizes. Normally designed so that the flow of fluid must make an non-straight turn inside the valve body which results in a desired loss of pressure across the valve when open which is greater than the loss across a gate valve. See GATE VALVE and GLOBE VALVE.

NEWTON
A unit of force based on the unit of mass, Kg (kilogram), multiplied by the acceleration, m/s2 (meters per second per second) which produces Kgm/s2, called the Newton. 1 N = 1 Kgm/s2 = 0.1225 lbs. (F) — (pounds force).

NIPPLE
The internal member or portion of a hose fitting.

NITRILE RUBBER ( NB/BUNA-N)
A family of acrylonitrile elastomers used extensively for industrial hose.

NITROGEN
An inert gas used to serve as an energy source for accumulators or to be used as a cleaning agent when pure, nonexplosive gases are required.

NOISE (Electrical)
Interference-type problems within electrical circuits and associated wiring that can cause erratic and improper operation of equipment.

NON-CONDUCTIVE
The inability to transfer an electrical charge.

NULL
The position of a device that is its normal or otherwise preset `zero' condition.