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Compressed Air Supply Questions and Answers

Before buying a compressor you need to know.

What pressure is required?
How much air will you need to use?  How many LPM or CFM.
Does the air need to be clean?
Does the air need to be dry?
Does the compressor need to be silent?  i.e. below 65 db.

Selecting a suitable air compressor.

Small Oil lubricated compressors are usually quieter but as they wear they can throw oil into the supply line which may or may not be an issue as some workshop machines or tools require lubrication in any case.

If clean air is the most important criteria, then an oil free compressor is what you require and addittional filters can be added to whichever specification you require.  If dry air is also important to prevent bacteria growth, then the oil free compressor will need to be fitted with a dryer.  Oil free compressors are also quiet when supplied in a dedicated soundproof cabinet.

Compressed air supply considerations

An air supply of up to 80 psi (5.5 Bar) is the pressure that you will find most small compressor units will supply but some provide less.  In house air (i.e. air supplied to a clean-room or workshop from a large central compressor) will likely be reduced by “pressure drop” due to an extended distance to the outlet or, by other users closer to the compressor.  Because of these issues, a small, dedicated compressor is sometimes the best way to keep the pressure and flow constant.

It is most important to know how much air i.e. how many LPM (litres per minute) or CFM (cubic feet per minute) the machine you are using requires, as well as the required pressure in PSI (pounds per square inch) or (BAR).

How the compressed air is generated

The amount of air supplied is determined by the volume which the pump unit can generate depending on its size or the speed it operates.  Overuse or leaking air will deplete the amount stored in the compressor’s tank and cause the pump to run, sometimes continuously.  Most compressors are designed to run 50% of the time and others are 100% rated, however, in a warm atmosphere, any compressor can overheat and in such circumstances it will fail.

At LPL we prefer that our customers ask our opinion to ensure they buy the correct compressor.

Ken Marshall
Director of Engineering
Laboratory Precision Ltd. ©