ROTORCOMP NK 100, Operating Manual

Page: 15 / 52

Operating Manual - NK 100
[en] 09/2008 3.7
3.7.2 Starting
In the startup phase the intake control valve is
closed via the spring 3-7/3 . The rotors in the screw
compressor 4 intake air via a bypass hole with a
non-return valve in the intake control valve and
relief valve.
This air is compressed and the pressure in the
separator slowly increases. This pressure is
routed via the control unit 3 before the holding pis-
ton 3-7/6 . This presses the holding piston toward
the rear and the control piston 3-7/4 opens the
intake control valve with the spring.
The desired final pressure can be set on the pro-
portional control valve 3.1 .
When the set final pressure is almost reached,
the proportional control valve 3.1 opens and com-
pressed air is routed behind the control pis-
ton 3-7/4 . As a result, the control piston is pressed
toward the front and the valve plate 3-7/5 closes
the intake control valve. If the operating pressure
drops, the proportional control valve closes and
the intake control valve opens again. The propor-
tional control valve steplessly controls the opening
of the intake control valve depending on the oper-
ating pressure.
3.7.3 Feed mode
The air drawn in flows via the intake filter 1
through the intake control valve 2 directly into the
compression chamber of the screw compressor 4 .
There the intake air is compressed and oil for lubri-
cation 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 flows via the fine separator 6 and the
minimum pressure valve 7 to the compressed air
outlet.
In the fine separator 6 the oil is filtered 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 backflow of the compressed air out of the
system into the compression chamber in the dis-
charge phase.
During startup a faster pressure buildup is also
ensured, which is required for optimum lubrication
and oil separation.
The heat resulting during compression is dissi-
pated via the oil-air mixture. The oil circulation also
results from the pressure difference between the
outlet and inlet pressure. The optimum operating
temperature for the oil is adjusted by the oil ther-
mostat 8 . Depending on the oil temperature, the oil
flow is routed directly via the oil cooler 10 or
directly to the oil filter 9 by the thermostat valve.
The oil then flows via the oil filter 9 to the various
injection points in the compressor block.
3.7.4 Stopping
When switching off the system, the valve
plate 3-7/5 closes the intake control valve immedi-
ately with the spring 3-7/8 . This causes pressure
to build up in the intake chamber. This pressure
actuates a piston in the relief valve 3.2 and the
separator is discharged via holes in the relief valve
and intake control valves in the intake filter 1 .
3.7.5 Switching off
When switching off the system, the intake control
valve 2 operates, supported by spring pressure,
as an independent non-return valve and closes
the intake opening oil-tight.