Johnson Controls SABROE SAB 355 S - Cold-Start System; High-Stage Unit Operation

Operating manual- SAB 355 (including ATEX)
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Operating instructions
Fig. 18
Note: The sectional view shows the valve structure. Some of the internal oil channels are not
visible.
6.11 Cold-start system
The unit is equipped with a special "cold-start" discharge valve. This valve ensures a rapid devel-
opment of oil pressure at initial start-up in order to lubricate the compressor without requiring an
oil pump, even in cold ambient temperatures with all pressures equalised.
Warning!
Be extremely careful when dismantling the cold-start valve on the discharge side of the unit, as
condensed refrigerant often is trapped between the cold-start valve and the stop valve. A bleed
valve on the side of the check valve is used to vent the space between the check valve and the
stop valve.
Exposure to refrigerant fumes can cause injury or death.
Warning!
Inside the valve, there is a very heavy, tight spring. Provided the valve is intact, the spring
presents no danger when dismantling.
High-stage units
For high-stage units, the cold-start valve is equipped with a large spring which creates a 2.0 bar
[30 psi] pressure in the oil separator (above suction pressure) for lubrication of the compressor.
Once the compressor is running it will begin to force gas to the condenser at connection P2.
As the condenser heats up, the pressure will begin to rise as the compressor suction pulls down in
pressure. As soon as a differential pressure has developed between the condenser and suction
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