Eficiencia De Compresor

EFFICIENT COMPRESSED
AIR SYSTEMS
AIR AND MINE EQUIPMENT
INSTITUTE OF AUSTRALIA

HOW TO SAVE ENERGY, REDUCE COSTS AND HELP THE ENVIRONMENT

2 COMPRESSED AIR - EFFICIENT UTILISATION

Equipment selection and system design
play an important role in lowering the
costs of producing compressed air (see
Efficient Compressed Air Systems 1.
Compressed Air Selection and Efficient
Production).However, purchasing an
efficient system is not all there is to
saving energy and money. Ensuring
that installed systems are running as
efficiently as possible can allow you to
make great gains.

Table 1. Air Leakage And Annual Energy Wastage By Equivalent Hole Diameter

LEAKS

The first step is to be able to distinguish between base leakage and minimum usage. End-uses such
asinstrumentation or agitation systems, which need to operate 24 hours a day, can sometimes be
confused with leakage. There are several methods that can be used to measure the level of compressed
air leakage.

Equivalent hole
diameter (mm)

●

●

●

●

Annual energy
waste (kWh)

Annual cost of
leaks ($ AUD)

0.4

0.2

133

$13

0.8

0.8

532

$53

1.6

3.2

2,128

$2133.2

12.8

8,512

$851

6.4

51.2

34,040

$3,404

12.7

Leaks can be a significant source of wasted energy in
an industrial compressed air system and may be costing
you much more than you think. Audits typically find
that leaks can be responsible for between 20-50% of
a compressor’s output making them the largest single
waste of energy. In addition to being a source ofwasted
energy, leaks can also contribute to other operating
losses:

Quantity of air
lost in leaks (l/s)

204.8

136,192

$13,619

For compressors that use start/stop controls, the method involves starting the compressor when there
are no demands on the system, that is when all the air-operated end-use equipment is turned off. Air
escaping through the leaks will cause pressure drops,which in turn will make the compressor load and
unload. Measurements to determine the average time it takes to load and unload can then be taken.
Total leakage expressed in terms of the percentage of compressor capacity lost can be calculated as
follows:1

Leaks cause a drop in system pressure. This can
decrease the efficiency of air tools and adversely
affect production

LEAKAGE (%) = [(T X100)/(T+t)]1
WHERE

Leaks can force the equipment to cycle more
frequently, shortening the life of almost all
system equipment (including the compressor
package itself)

T = ON-LOAD TIME AND
t = OFF-LOAD TIME

In systems without on/off controls leakage, can be estimated if there is a pressure gauge downstream
of the receiver. This method requires an estimate of total system volume,including any air receivers,
air mains, and piping that are downstream of the receiver isolating valve (V, in cubic metres). The
system is then run at normal operating pressure (P1). You will then need to record the time (T) it
takes for the system to drop to a lower pressure (P2), which should be a point equal to about one-half
the operating pressure. Leakage can be calculated as follows:Leaks can increase running time that can lead
to additional maintenance requirements and
increased unscheduled downtime
Leaks can lead to adding unnecessary
compressor capacity

LEAKAGE (m3/s) = (V X (P1-P2)/T(SECS)1
WHERE: V TOTAL SYSTEM VOLUME IS CUBIC METRES
P1 AND P2 ARE IN BAR(g)
T IS IN SECONDS

Therefore, proactive leak detection and repair can have
a significant effect on yourbusiness. Table 1 lists the
estimated amount of air leaks for a system operating at
a pressure of 700 kPa, for 2000 hours per year and the
energy wasted.
1

UK Department of Environment Transport and Regions, Good Practice Guide 126, 1994

You can estimate the annual cost of the leakage by using the formula:2
0.4 X (COST PER KWH IN $) X (NO. OF HOURS RUN PER YEAR) X (LEAKAGE RATE IN...