If your company uses compressed air it’s worth regularly checking the system for leaks. Compressing air takes a lot of energy, making it a very expensive utility, particularly if there are leaks in the system.

Our compressor switches on when the system pressure drops below 8 barg and then switches off when the pressure reaches 9 barg. With a system like this, it’s quite easy to measure how much leakage there is. First, find a time when no equipment that uses compressed air is switched on – usually the end of the day when everyone has gone home. Wait for the system pressure to drop below 8 bar and then measure the time (T1) that the compressor needs to be on in order to charge the system back to 9 bar. When the compressor switches itself off, measure the time taken for the system pressure to drop below 8 bar again (T2). You can then calculate the leakage as a percentage using the following formula:

[T1/(T1 + T2)] x 100 = leakage (%)

When I first did this test, our compressor leakage was 10%. This meant that for 10% of the time that the compressor was on, it was purely feeding the leaks in the system. Our compressor was rated at 7.5 kW and was sometimes being left on overnight when nothing uses compressed air. By finding and fixing the leaks we reduced leakage to below 1.5% and we now make sure that compressors are switched off overnight where possible. This, combined with our other energy saving measures, is what helped to reduce our energy consumption by 10%.

We were able to reduce our leakage by so much because our system is quite small. In large plants with big compressors and many items of equipment using compressed air, it is common to have leakage of 20% and if you can get that down to 10% your doing very well.