How much do air leaks really cost?
The highest cost associated with air compressor ownership,
is not the cost of the compressor, or the cost of preventative maintenance, but
the electrical cost associated with running the compressor itself. With the electrical
cost being the most expensive portion of compressor ownership, can you really
afford to run a compressor unnecessarily? Well, let’s examine this a little
further.
First, we should look at how electrical companies charge for
your electricity. The standard billing is measured in Kw/H (Kilowatts per
hour). Electrical rates vary greatly depending on time of day, location, and
total usage, but for our example we’ll use a rate of 16 cents per Kilowatt Hour.
The next step is to figure out how much electricity we’re
using; our example is using a 5hp compressor. To convert horsepower to kilowatt,
multiply the horsepower rating by .74. So, 5 horsepower x .74 gives us 3.7 kilowatts.
Getting closer now, we’ve got to figure out how long the
compressor runs. We’ll use a conservative rating of %50. So, during an 8 hour
shift, we’ll assume that the air compressor is running for 4 hours. If we work
with a single shift operation, and based our example on 5 days a week, 52 weeks
a year, we come up with 4 hours a day x 5 days a week x 52 weeks per year = 1040 run hours per year.
And finally, 1040 hours per year x 3.7 kilowatts x 16 cents
per Kw/H = $ 615.68 per year.
Doesn’t sound like much, and perhaps it’s not, however, we
are talking a small compressor, in a small shop, with relatively low run time.
However, does it really need to be this high? At just about any shop you walk
through, you can hear air leaks. Many times people think these leaks aren’t
anything to be concerned with, and that they are so small, that they won’t
matter, I disagree. I think it’s fair to say, that an average shop would have
the equivalent of a 1/16” holes worth of air leaks – from hose quick
disconnects, leaking fittings, leaking tool, leaking drains, or a host of other
sources. Think about it this way; a 1/16” of an inch is about the size of the
tip of a pen, really not large at all, but at this size, and at 125psi of
pressure, there is waste of 7.9 CFM worth of air. So, how much is 7.9 CFM?
Well, remember that 5hp compressor we started our example with? Well, this
compressor delivers an average of 17.5 CFM, so there is %45 waste of the total
capacity.
It should be noted as well, that the amount of air that's wasted is exponential when compared to the diameter of the hole; at 1/16th of an inch, at 150psi, the leak rate is 9.1CFM, at 1/8th of an inch, that number more than triples to 37.3CFM!
So, in the system above, if the leaks were eliminated, there
would be a 45% reduction in electrical usage, so the $615.58 annual costs would
drop to 338.62.
How many horsepower worth of compressed are do you have? How
many shifts do you run? How much can YOU save?At Air Compressor Works, we work on compressors from ½ a horsepower up to 300hp and larger, and our staff of highly trained service technicians and salesmen are constantly on the look out for ways to make your compressed air system more efficient. Give us a call, and let us find ways to save you money on your compressed air system.
Wayne Holtzclaw, Technical Service Manager, Air Compressor Works, Inc.
