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GLOSSARY

After Cooler:A heat exchanger mounted on acompressor outlet to extract the heat of compression.Ambient:The conditions, usually temperature,in the vacinity of the equipment under normal working conditions.Back Pressure Regulator:A device connected to a system in such a way that the system pressure is held effectively constant by control of the outlet flow to atmos-phere.Check Valve:A device which allows flow in onedirection only.Coalescing:The action causing small particles tounite to form larger particles.Deliquescent Dryer:A dryer using material whichabsorbs water vapour to such anextent that the material ultimately dissolves into the water it absorbs.Desiccant:An adsorbing material used in somedryers. Many such dryers are regenerative in that they use some of their energy to dry the material making it suitable for reuse.Drip Leg Drain:A device at the bottom of a down legfrom a distribution main or a systemlow spot to remove condensed waterfrom the system. Such devices are normally fitted with automatic drain valves.Dump Valve:A valve which is connected toatmosphere in such a way as to rapidly exhaust the system pressure.Emulsion:A mixture of oil and water.Failure Flow:The maximum flow through a device at a given pressure with the valve open to maximum extent. Flow Characteristics:A characteristic of a pressureregulator which shows the variation of outlet pressure with varying outlet flow rates at a constant supplypressure.Free Air:Air flow measure in dm Regulation Characteristic:A characteristic of a pressureregulator which shows the variation of outlet pressure with varying inlet pressure at a constant flow rate.Relative Humidity:The ratio of the actual amount ofwater vapour present in a given volume of air, to the amount of water vapour necessary to saturate the same volume of air at the same temperature.Soft Start Valve:A device which on initial pressurisa-tion of a system allows the pressure to build up slowly to a pre-deter- mined intermediate level before allowing a step-up to full line pressure to be achieved.
3 /s at STP(1013mbar and 21°C) (ISO R554). All air flows are converted to this to make system sizing easier.Initial Droop:The amount of pressure dropincurred by a pressure regulator in going from a flow (static) condition to a small flow (dynamic) condition.Micro-Fog:A suspension of light oil fractions inair, typically less than 2 µm in size which can travel long distances, through complex passageways.Micron (micrometre):A measurement of size on millionthof a metre (symbolµm).Oil-Fog:A suspension of oil fractions in air,heavier and larger than Micro-Fog, suitable for heavy duty lubrication.Pilot Operated Regulator:A regulator which has its outlet pressure controlled by the outlet pressure of another (piloting)pressure regulator, and not by anintegral adjustable spring load as with standard pressure regulators.Porting Block:A modular device for allowingseveral air take-off from a main air flow control set.Pressure Drop (Droop):The amount of pressure loss incurred by the flow of air through adevice.Pressure Reducing Valve/PressureRegulator: A device which is used to lower air pressure in a pneumatic system to a desired working level.
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