Glossary

Operations and maintenance.

Optical character recognition.

Outside diameter.

A quality of gases, vapours, or particles which stimulates the olfactory organs; typically unpleasant or objectionable.

Original equipment manufacturer.

(From "olfactory") A perceived air quality term which attempts to quantify a given pollution load. One person creates 1 olf of bioeffluents. If there are 10 cubic meters of floor space per person, then people create 0.1 olf per m² (olf/m²). Other sources are compared and quantified by olfs. For example, if 40% of the people smoke, this adds 0.2 olf/m² to the load.

A simple control system in which the device being controlled is either full on or full off, with no intermediate operating positions.

A visual or optical measure of the obstruction of light by solid particulates and liquid droplets suspended in air.

Burning of combustibles without confinement of fuels, flames, or emissions.

A break in an electrical circuit that prevents normal current flow.

Insurance on the shipment without expiry date which provides an automatic coverage of the shipload for or from a policy-holder according to specific commercial conditions (rates, terms and conditions). In general, the marine insurance policy is different from the war insurance policy.

Temperature that satisfies the greatest possible number of people at a given clothing and activity level.

An investor who purchases an option has the right, but not the obligation, to buy or sell certain securities at a specified price within a specified time. A put option gives the holder the right to sell the security, a call option gives the right to buy the security.

A device for measuring gas flow by measuring the pressure drop across an orifice in the flow line.

Operating system.

Occupational Safety and Health Act (or Administration).

Air taken from the external atmosphere and, therefore, not previously circulated through the system.

Outdoor air is the "fresh" air mixed with return air (RA) to dilute contaminants in the supply air.

Capacity, duty, performance, net refrigeration produced by system.

The shaft of a speed reducer assembly that is connected to the load. This may also be called the drive shaft or the slow speed shaft.

Any opening used as an entry for air from outdoors.

Pressure differential above a reference pressure, usually ambient atmospheric pressure.

Major constituent of the earth’s atmosphere.
Method: Inject nitrogen into the room and measure the rate at which the oxygen concentration returns to normal.
Detector: Paramagnetic analyser.
Advantages: Non-toxic.
Disadvantages: Large background concentration compared with the changes in concentration to be measured. Consumed by occupants. Consumed by combustion.

Ounce.

Ounces per square foot.