Engineering manual - SAB 193-233-283 S A-frame (including ATEX)
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008831 en 2020.10
Technical description
ATEX:
On ATEX-executions, the heating element(s) are ATEX-approved. Heating elements from Johnson
Controls Denmark have a thermostat with manual reset. If the thermostat drops out, only compe-
tent personnel should reactivate it.
4.24 Oil level switch
Fig. 31: Oil level switch
Two oil level switches may be mounted on the oil separator.
During normal operation the lower switch must always be activated. If the oil level drops below
minimum, the switch will deactivate, and this will be registered on the UniSAB III control system.
The upper switch (optional) gives signal to an oil equalising system, which equalises the oil return
from the plant between several units.
4.25 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.
F
our red LEDs
Plast housing
M4 fixing screw
NW27
1/2 “ BSP
Tube AISI304
Dia. 15 mm
PROCAP -LS20
105 mm
77 mm
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