This is a pressure measured from a base of absolute zero. We breathe air at a pressure of approximately 14.7 pounds per square inch absolute (psia). We don’t notice this pressure because it is always around us – and its called atmospheric pressure. However, if we look at an unused pressure gauge it reads 0 psi. The absolute pressure of a system therefore equals the sum of Atmospheric Pressure and Gauge Pressure. In fact the British Standard Atmosphere is 14.696 psia. Also see PSIG.
This is a temperature measured from absolute zero which is approximately -273.15 deg C and is usually referred to as 0 deg K. (ie 0 deg K = – 273.15 deg C)
These are either axial or centrifugal machines. Pressure is imparted to the air by speeding the air up, and then diffusing the velocity head into static head. These machines will ultimately stall, unlike a positive displacement machine.
A heat exchanger fitted after a compressor to cool down the discharged compressed air. An aftercooler is usually either air-blast, or water cooled.
Three letters which require a volume to accurately define. Generally accepted as the mixture of gases found on the earth’s crust. The water vapour content of air varies dramatically and when considering alternate bids for a new compressor, the moisture content (RH) stated by each prospective supplier should be the same, as should the inlet pressure and inlet temperature.
Atmosphere normale de reference. The term ANR is not usually applied to cfm, it is the new (sick) European replacement for FAD and usually follows the metric measurement of air flow, such as Cu Metres per Minute ANR.
Sometimes called a pulsation damper this is a small receiver fitted on the inlet or discharge of a reciprocating compressor. The device is designed to remove the resonance from the compressor thereby reducing noise.
This pressure varies the world over and fluctuates with weather conditions. It is also dependent upon altitude.
An official examination to determine inputs and outputs of a system in a manner that can illustrate the current situation. Compressed air audits are becoming fairly common, but many businesses end up paying a lot of money for a simple flow test. Whenever we lose a job to a competitor, its because the client thinks that sticking a few flow meters into a factory ringmain constitutes an audit. The resulting data is invariably then popped into a fat report that contains a meaningless list of the production equipment on site.
The summary of a proper compressed air audit should depict hard information in the same way that twin entry book-keeping shows the in’s and out’s of money flowing through a business. Inputs to the compressor house include energy, water, labour, oils, spare parts, repair costs, etc. Outputs include compressed air for production, air leaks, heat losses, filtration/drying costs, emissions to air/land/water, noise emissions, transmission and distribution losses etc. From this information, the Conversion Efficiency for the compressed air system can be calculated. The client / consultant can then review the findings of the audit with a view towards increasing the Conversion Efficiency.
Cashflo compressed air audits also encompass SHE investigations. This additional information may not increase compressor conversion efficiency, but it does ensure that the client is up to date with the Safety, Health and Environmental aspects of producing and using compressed air.
Auto Ignition Temperature (AIT):
The temperature at which a mixture of air and flammable gas/material will spontaneously ignite, without the assistance of spark or flame.
An aerodynamic machine, usually multistage. The air is drawn through a series of rotors (propeller like) and stators until the desired working pressure is achieved. It is called axial because the air essentially enters one end of the compressor and is ejected at pressure from the other end.