Maintenance Technology July 2017 - 22

ENERGY EFFICIENCY

Untangle

Compressed Air
Misconceptions
COMPRESSEDAIR SYSTEMS are often misunderstood.
That's why so many seem to be inefficient. The problem,
according to compressed-air expert Ron Marshall, is that
inefficiency constantly gnaws away at your bottom line through
extra operating costs and, in some cases, reduced productionoutput capabilities. He knows what he's talking about-and has
been writing about it in Maintenance Technology's pages for
several years (see Learn More Box, p. 24).
Marshall's background includes, among other things,
having been the first Canadian participant to qualify as a U.S.
Department of Energy (USDOE) AIRMaster+ specialist and
long-time involvement as a committee member and instructor
with USDOE's Compressed Air Challenge initiative (compressedairchallenge.org). He discusses several of the most widespread
(and troubling) compressed-air misconceptions here.

Misconception: Compressed air is free.
"This one," Marshall noted, "is a common belief among
personnel who don't have to pay a plant's electrical bill." In
reality, using compressed air to drive any continuous mechanical operation can be very costly and inefficient. It takes about
7 to 8 hp of electrical power at the compressor to produce an
equivalent of about 1 hp of mechanical output at a compressedair-driven device, making it one of the most expensive energy
consumers in your plant. Most of the energy ends up as heat

22 |

MAINTENANCE TECHNOLOGY

Where air compressors
are concerned, what
you believe may not
be rooted in fact and
could be costing
your operation.
Jane Alexander
Managing Editor

in the compressor room, and often is simply blown into the
atmosphere, warming the globe. Frequently, problems with the
compressor control system, pressure restrictions, and extensive
leakage make the 8:1 power ratio even worse.
When it comes to using compressed air to blow dust, turn
an air motor, or agitate liquid, Marshall said it's important to
calculate energy-related costs associated with the operation.
While it's important to understand these costs yourself, it's also
important to educate others in your plant that compressed air is
a very costly utility-and one that shouldn't be wasted through
inappropriate use.

Misconception: Fixing leaks saves big money.
According to Marshall, studies have shown that leaks waste
between 20% and 30% of all the compressed air produced in
industrial plants. Some plants with no leakage-detection-andrepair programs have even higher levels. Wasting 50% is not
unheard of and, in some extreme cases, it can approach 80%.
"Considering the high cost of compressed air, leakagereduction efforts have a high potential to reduce operating
costs, Marshall stated, "but there's a catch." The energy savings
you gain through leakage reduction is not always directly
proportional to the flow reduction, but, rather, depends on the
compressor control method. A very well-controlled system
will turn the compressor energy down for every percent drop
JULY 2017

http://www.compressedairchallenge.org

Table of Contents for the Digital Edition of Maintenance Technology July 2017