Do you know how much your compressed air leaks cost you? Maybe not but it is quite easy to work out.
Step 1 – Turn off all your machines that use air.
Step 2 – Run your compressor till it stops and note the pressure in the receiver.
Step 3 – Start your stopwatch
Step 4 – turn off your compressor
Step 5 – time how long it takes for the pressure to fall by 1 bar (time = T in seconds)
To calculate, proceed as follows:
V = Receiver voume in litres
H = Hours per week that your factory or workshop is operational
E = Electric costs in £ per KWH
V x 60
———– = leak rate in cubic metres / min (LR)
T x 1000
A screw compressor will (typically) deliver approximately 0.149 cubic metres/minute free air at 8 bar per KW.
KW required to maintain leak = LR/0.149
Cost per year = KW x E x H x 52
This in only an approximate calculation but is sufficiently accurate for all practical purposes in industry and can be used for any size of factory.
Air receiver is 500 litres and it took 45 seconds for the pressure to fall from 7 to 6 bar.
Electric cost is £0.15 per KWH and the shift pattern is 16 hours a day, 5 days per week = 80 hours per week.
500 x 60
————- = 0.667 cubic metres / minute (Leak Rate = LR)
45 x 1000
Cost per year = (0.667/0.149) x 0.15 x 80 x 52 = £2,793 in electricity costs alone.
In addition to the electricity cost is the servicing and capital cost of the compressor although this is typically somewhat less that the electricity costs (estimate 20-25% of the electricity cost).
Do not tolerate compressed air leaks of any kind!!