Octave
Frequency difference between harmonic vibrations: the doubling of the frequency of sound.
Octyl Alcohol-ethyl Hexanol
Additive in absorption machines that reduces surface tension in absorber.
Odor
The property of air contaminants that affect the sense of smell.
Off Cycle
Segment of refrigeration cycle when system is not operating.
Offset
In a proportional control system, the deviation between the set point and the control point. Also called error.
Ohm
Unit of easement of electrical resistance. One ohm exists when one volt causes a flow of one ampere.
Ohmmeter
Instrument for measuring electrical resistance in ohms.
Ohm's Law
Mathematical relationship between voltage, current, and resistance in an electric circuit: discovered by George Simon Ohm. It is stated as follows voltage (E) equals amperes (l) times ohms (R): or E=I X R.
Oil Refrigeration
Specially prepared oil used in refrigerator mechanism which circulates, to some extent, with refrigerant.
Oil, Refrigeration
Specially prepared oil used in refrigerator mechanism which circulates, to some extent, with refrigerant.
Oil Binding
Condition in which oil layer on top of refrigerant liquid may prevent it from evaporating at normal pressure and temperature.
Oil Burner
A device for burning vaporized oil (gas) to produce heat.
Oil Bushing
Assembly in which a shaft passes through a sintering, bushing (which is impregnated with oil). Bushing is permanently lubricated.
Oil Level Regulator
A device that controls the oil level in the compressor.
Oil Pressure Safety Cutout
Motor protection device that senses oil pressure in the compressor. It is wired in series which the compressor and will shut it off during periods of low oil pressure.
Oil Reservoir
Container that stores the compressors oil supply.
Oil Ring
Lower piston ring.
Oil Separator
Device used to remove oil from gaseous refrigerant..
Oil Slugging
Oil being pumped out of the compressor
One way Valve
A Valve with only one opening that can be either opened or closed.
Open Circuit
Interrupted electrical circuit, which stops flow of electricity.
Open Compressor
Term used to indicate an external drive compressor (not hermetic).
Open-cycle Refrigeration
Refrigeration system I which the refrigerant is released to the atmosphere after evaporation.
Open Display Case
Commercial refrigerator designed to maintain its contents at refrigerating temperatures even though the contents are in an open case.
Open System
Refrigerating system which used a belt driven or a coupling-driven compressor.
Operating Controls
Devices used to cause a refrigeration system to maintain desired conditions.
Operating Differential
The actual temperature or pressure difference in the conditioned area.
Operating Pressure
Actual pressure at which the system works under normal conditions. This pressure may be positive or negative (vacuum).
Organic
Pertaining to or derived from living organisms
Orifice
Accurate size opening for controlling fluid flow
Orifice Tube
Metering device consisting of a restricting tube with inlet and outlet screens.
O'rings
Sealing devices used between parts where there may be some motion.
Oscilloscope
Fluorescent-coated tube that visually shows an electrical wave.
Overload
Load greater than that for which the system was intended.
Overload protector
Device, either temperature, pressure, or current operated, that will stop operation of unit if dangerous conditions arise.
Oxidation
The chemical combining of oxygen with a specific material, resulting in deterioration of that material.
Oxygen
An elemental gas that comprises approximately 25% of the atmosphere. It is required for combustion.
Ozone
A form of oxygen, O3, having three atoms to the molecule, usually produced by discharge of electricity through the air. The ozone layer is the outermost layer of the earth's atmosphere, that absorbs ultraviolet light from the sun and shields the lower layers and the earth from harmful rays.