ROTORCOMP NK 31 - Relieved Stating; Feed Phase; Switching off

3.3
[en] 02/2014
Installation and operating manual - NK 31
3.3.4 Switching off
When the system is switched off, the intake
valve 2, operates, supported by spring pressure,
as an independent non-return valve. After being
switched off, the deenergized solenoid valve 3.1
also opens and compressed air ows into the
control piston of the intake valve 2. The intake
opening is closed off oil-tight in the process, and
then the system is completely relieved via the no-
load/ relief nozzle 2.1 (see Figure 3-5).
3.3.2 Relieved stating
During relieved starting a small air quantity is
already drawn in at a minimum vacuum by the ro-
tor rotation. This air quantity is then compressed
and ows as pilot air via the deenergized, open
solenoid valve 3.1 under the piston of the control
valve. The intake valve 2 closes and remains in
the no-load position. In this throttled position a
corresponding air quantity is drawn in at a certain
compressor rotational speed so that a residual
pressure of approx. 2 bar is maintained in the
separator tank 5. The compressed air ows into
the intake lter 1 via the no-load nozzle 2.1 of the
intake valve 2 to relieve the system.
3.3.3 Feed phase
During the feed phase the solenoid valve 3.1
is closed electrically. The control pressure of
the intake valve 2 is released via the no-load
nozzle 2.1. The intake valve 2 opens due to the
spring force and the vacuum in the intake cham-
ber of the compressor. The air drawn in ows via
the intake lter 1 through the intake valve 2 di-
rectly into the compression chamber of the screw
compressor 4. There the intake air is compressed
and oil for lubrication and cooling is injected.
The oil-air mixture then enters the separator
tank 5 in which the majority of the oil is separated
from the air. The air then ows via the ne sepa-
rator 6 and the minimum pressure valve 7 to the
compressed air outlet.
In the ne separator 6 the oil is ltered out down
to a residual content of < 3 mg/m
3
and then
routed back into the compressor housing via a
nozzle and a non-return valve 12.
When the compressor is switched off, the mini-
mum pressure valve 7 with a non-return function
prevents backow of the compressed air out of
the system into the compression chamber in the
discharge phase.
During startup a faster pressure buildup is also
ensured, which is required for optimum lubrica-
tion and oil separation.
The heat resulting during compression is dis-
sipated via the oil-air mixture. The oil circulation
also results from the pressure difference between
the outlet and inlet pressure. The optimum oper-
ating temperature for the oil is adjusted by the oil
thermostat 8. Depending on the oil temperature,
the oil ow is routed directly via the oil cooler 10
or directly to the oil lter 9 by the oil thermostat
valve.
The oil then ows via the oil lter 9 to the various
injection points in the compressor block.