Compressed Air Leaks – The Evil Hiss

Compressed air systems leak a bit, but not worth worrying about. Right? The shrug and ignore, business as usual approach is common. What a waste of an excellent opportunity to make big savings.

While assessing energy at factory, Grey Green’s engineers where able to measure compressed air leakage rate. Our client kindly agreed to leave all machines except their air compressor off for a few minutes. The photographs show the results.

The compressor is:
• An oil injected rotary screw machine
(by far the most common type used in SA factories).
• Relatively new, and fitted with a VSD (variable speed drive).

The photographs are of the display on the compressor when no other machines were running. The percentages show the speed of the compressor. Since it is a screw compressor, the percentages also indicate the proportion of rated flow rate which the compressor is delivering – an average of 41 %, when nothing else in the factory was on! 41 % of rated flow was feeding leaks!

Assume:
• A 75 kW compressor supplying air to a system
with the same leakage rate
• Electricity cost of 65 c/kWh
• 2 shifts a day, 5 days a week, 48 weeks a year,
i.e. 3 840 hours operation a year.

Then:
• Wasted power = 0.41 x 75 = 31 kW
• Wasted energy = 118 080 kWh
• Wasted expenditure = R 76 750

Cost of locating and fixing leaks? Usually nothing more than time when a maintenance fitter is not busy with breakdowns.

Need help in getting started? Wondering what else could be improved on your compressed air system? Contact Grey Green now.