12
C6.2.26/1013-1116/E
Figure 7: Suction tube design
compressor. This results in a condition of system pressures equalising through the compressor
which can cause the compressor to slowly rotate until the pressures equalise. This condition
does not affect compressor durability but can cause unexpected sound after the compressor is
turned off.
3.7 Suction line noise and vibration
Proper pipe design must be taken into consideration when connecting a scroll compressor to the
system.
A scroll compressor makes both a rocking and
twisting motion and enough flexibility must be
provided in the pipe-lines to allow starting, stopping
and steady state running of the compressor without
transmitting excessive stress into any line attached
to the unit. In a split system, the most important
goal is to ensure minimal vibration in all directions
to avoid transmitting vibrations to the structure to
which the lines are fastened.
Under some conditions, the Copeland Scroll has a
normal starting rotational motion that can transmit
a transient noise along the lines. This may be
particularly pronounced in compressors using a
three-phase motor due to their inherently higher
starting torque. This phenomenon, like the one
described previously, can easily be avoided by
using standard line isolation techniques.
The sound level of a system is the result of design, quality and application. Scroll compressors
sound power levels generally increase with the compressor model capacity and the condition
pressure ratio.
