Compressors / compressed air - Aircraft

9 Sound pressure level and
sound power level
We indicate the sound power level LWA as well as the sound pressure
level LPA for the sound levels on our compressors. In order to
demonstrate that such values are not compared to one another and
cannot be compared with other noise levels, e.g. for aircrafts we give
you a short explanation how to determine the two values below.
· Sound pressure level L P A
The volume is defined by its proper value by the sound pressure
or by the logarithmic sound pressure level. The sound pressure
describes the actual effect of a sound source on the air pressure and
thus on the human hearing. It is directly measured and is always
depending on the distance to the sound source and on the acoustical
conditions in the room. The sound pressure level is the value which
is used to determine the occupational safety and health protection
(Occupational health and safety regulations).
· Sound power level L w A
The sound power determines the sound energy emitted by a sound
source for each time unit. It can be determined by measuring the
sound pressure at several places on an enclosed enveloping surface
around the sound source. This value is not directly measured but
calculated and does not depend on the distance or on the acoustics
of the room. The sound power level for instance serves
to define legal limit values when using devices outdoors (Outdoor
directive).
10 Determination of the compressed air requirement
Most work cycles are only temporary. For these cycles, you may calculate an
average on time (ED). Furthermore, these consumers are generally used timedisplaced.
The average on-time (ED) and the factor of simultaneous f use are
included in the requirement reducing multiplication.
Overall compressed air consumption: In order to dimension your compressor
you should also take the following factors into consideration: losses due to
leakages, reserves and miscalculation.
Calculation example:
Compressed air working Duty cycle number Individual A x q x ED/100
consumption pressure ED (%) A (pcs.) consumption
(bar) q (l/min.)
Color spray gun
ø 1.5 mm
3 40 1 180 72
Blow out gun
ø 1.0 mm
6 10 3 65 19.5
Impact screw-driver
M 10
6 20 3 200 120
Drilling maschine
up to ø 20 mm
6 30 1 700 210
Angle grinder 6 40 2 500 400
Sum Q of the compressed air consumption of the consumers (l/min.) 821.5
Factor of simultaneous use f 0.71
Compressed air consumption of the consumers Qf = f x Q (l/min.) 583.3
13