over-sized compressor

Disadvantages of an over-sized compressor

In Information by ross

We have seen this mistake all to often. A customer comes to us after buying a “bargain” compressor either off a friend or auction site and for some reason it isn’t working as expected or more than likely it is costing them a fortune. When we look into it they have bought an over-sized machine thinking that bigger must be better. It isn’t, carry on reading to find out why!

If a compressor has been oversized for its intended purpose it will not operate as intended. This has several disadvantages to the end user.

Firstly the running costs will increase. You will typically find that when the compressor starts to fill the system it will do so very quickly, it will then however need to run in an ‘off-load’ state which allows the motor to cool down. This off-load period does not produce any useful compressed air and will still use almost the same power to operate. A correctly sized compressor will be matched to the sites air demand and will maintain the system pressure by running on-load as much as possible. Although running for longer by using a much smaller motor the system will run more efficiently. If the air demand changes throughout the working day a variable speed compressor is recommended for the most economical use.

Another downside of an oversized compressor not running correctly is that it needs to reach a certain running temperature in order to function correctly. If a compressor does not get its oil circuit hot enough moisture will start to form internally and eventually turn to liquid water. Normally this evaporates through the compressed air but if it doesn’t it will become trapped in the machine leading to rust and corrosion throughout its internal oil circuit. This will cause damage to the internal pressure vessels, piping, the screw rotas and the bearings. A failure on any of these points can permanently damage the compressor or even worse cause harm to someone if a component fails whilst under pressure.

If any damage occurs and a compressor is found to be over-sized this will not be covered by any warranty. This is standard across all compressor brands. This puts your investment at great risk if it was to ever go wrong as repairs associated with over-sized damage are usually costly.

You can talk to us today if you think your compressor is too large. We can install one of our data-loggers and produce a full report along with any recommendations to adjust your air system.