070.655-IOM (FEB 22)
Page 20
SBTP Rotary Screw Compressor
Operation
Volumizer volume ratio control
Open valve at SC3
Compressor Vi increase:
the volume ratio Vi is increased
when MSS solenoid valve YY3 is energized and oil flows
from the oil manifold through valve ports P and A to com-
pressor port SC3, enters the increase side of the cylinder
and overcomes spring tension.
Compressor Vi decrease:
the volume ratio Vi is decreased
when MSS solenoid valve YY4 is energized and oil flows
from SC3 through valve ports A and T to compressor port
T1.
To control the rate of Vi change, throttle the needle valve
at SC3 port.
Low ambient operation
Frick suggests insulating package oil separators as a mini-
mum requirement to preserve the heat generated by the
oil heaters, to prevent condensation, and secure lubrica-
tion at start-up.
Initial start-up
Before start-up, you must complete the prestart checklist.
See
Initial start-up procedure
After completing the prestart check, the compressor unit
is ready for start-up. It is important that an adequate gas
load be available to load test the unit at normal operating
conditions. Keep the following points in mind during initial
start-up:
1. For effective and safe operation, the compressor must
be run at the correct speed and discharge pressure.
Exceeding design conditions creates a potential hazard.
2. After 1 h to 3 h of operation adjust oil cooling system.
3. Pull and clean suction strainer after 24 h of operation.
If it is excessively dirty, repeat every 24 h until system
is clean. Otherwise, follow the normal maintenance
schedule.
4. Perform a vibration analysis if equipment is available.
Normal start-up procedure
1.
Confirm system conditions permit starting the com
-
pressor.
NOTICE
Ambient temperatures need to be high enough to
prevent excessive condensing; otherwise, initiate oil
heaters and heat tracing 24 h before start-up.
2. Start the unit.
3. Observe the compressor unit for mechanical tight-
ness of the external piping, bolts and valves. Ensure
that the machine has no oil and vapor leaks. If any of
these occur, shut down the compressor and correct the
problem as necessary using good safety practices.
P
Oil pressure in
T
Oil pressure out
SC1
YY1
YY2
YY3
YY4
SC-1
SC-2
SC-3
T1
SC2
1
1
A
A
P
P
T
T
B
B
1
2
2
2
2
2
2
1
1
1
1
2
BP
SC3
FC1
FC2
Optional flow control valve
Optional flow control valve
Volume ratio (VI) - Increase (slide stop)
Oil pressure out (internal)
Capacity - unload (slide valve)
Capacity - load (slide valve)
Hydraulic valve
top view
BP
SC2
SC1
SC3
Figure 20: Hydraulic schematic
