Natural Convection
See Convection, natural.
Natural Gas
A mixture of methane and other hydrocarbons found in the earth's crust, used as fuel. of an atom core which has no electrical neutral. Needle point valve: Valve having a needle point plug and a small seat orifice for low-flow metering.
Negative Temperature Coefficient Thermister (NTC)
Electronic thermistor that deceases in resistance as temperature increases.
Neoprene
Synthetic rubber that is resistant to hydrocarbon oil and gas.
Net capacity
The interior volume of a refrigeration cabinet.
Neutralizer
Substance used to counteract acids in a refrigeration system.
Neutron
That part
Newton
Force required to accelerate an object that has a mass of 1 kilogram to 1m/sec2.
Nitrogen
A gaseous element comprising three-fourths of the earth's atmosphere by weight.
Nitrogen dioxide (NO2)
Mildly poisonous gas often found in smog or automobile exhaust fumes.
No-frost Freezer
Low-temperature refrigerator cabinet in which no frost or ice collects on freezer surfaces or materials stored in cabinet.
Noise Dosimeter
Instrument used to measure sound.
Nominal Size Tubing
Tubing measurement that has an inside diameter the same as iron pipe.
Noncode Installation
Functional refrigerating system installed where there are no local, state, or national refrigeration codes in effect.
Noncondensable Gas
Gas which does not change into a liquid at operating temperatures and pressures.
Nonferrous
Group of metals and metal alloys that contain no iron.
Nonfrosting Evaporator
Evaporator that never collects frost or ice on its surface.
Nominductive Load
An electrical load consisting of resistance, which does not affect the power factor.
Normal Charge
Thermal element charge that is part liquid and part gas under all operating conditions.
North Pole, Magnetic
End of magnet out of which magnetic lines of force flow.
NTC
See Negative temperature coefficient thermistor.