Air leaks are much easier to ignore than oil leaks because they don't draw attention to themselves in the same way.
a
You don't need to worry yourself with clean-up and disposal costs. Contaminant ingression is possible, but is generally not a major concern.
a
And unless the leak is significant, safety is not usually a big issue either. So that leaves make-up fluid (air).
l
While air is free - clean, dry compressed air is NOT.
a
In considering the cost of make-up air for a pneumatic system the following need to be considered:
a
Depreciation (wear and tear) of the compressor; Conditioning costs - filtration, drying and lubrication; and Energy cost of compression.
a
The ideal leakage rate is of course zero, but when calculating the free-air delivery (FAD) required by a pneumatic system a rule of thumb is to allow for leakage of 10% of total flow rate.
a
Consider a 10 cubic meter/minute system leaking 10% or 1 cubic meter/minute. The power required to compress 1 cubic meter (35.3 cubic feet) of air per minute to a pressure of 6 bar (90 PSI) is approximately 5.2 kilowatts. At an electricity cost of $0.10 per kilowatt-hour this leakage is costing over 50 cents per hour in electricity consumption alone.
a
In a 24/7/365 operation that amounts to $4500 per year!
a
While a leakage rate of 10% of flow rate may sound high and would be unsustainable in a hydraulic system, air leakage rates as high as 25% are not unheard of even in apparently well maintained pneumatic systems!
As demonstrated by the above example, the annual cost of air leaks in pneumatic systems can be significant in power consumption alone.
a a Craig Cook