Specifications

Technical description
DRYPOINT RA 80 – 720 23
5.13. Refrigerant Pressure Switches P
A
- P
B
-P
V
As operation safety and protection of the dryer a series of pressure switches are installed in the gas circuit.
PB :
Low-pressure controller device on the suction side (carter) of the compressor, is enabled only if the pressure
drops below the pre-set value. The values are automatically reset when the nominal conditions are restored.
Calibrated pressure : R 404 A Stop 1.0 barg - Restart 5.0 barg
PA :
This high-pressure controller device, located on the pushing discharge side on the compressor, is activated
when the pressure exceeds the pre-set value. It features a manual-resetting button mounted on the controller
itself.
Calibrated pressure : R 404 A Stop 32 barg - Manual reset
PV : DRYPOINT RA 80-360 Fan control pressure switch located on the pushing side on the compressor. It keeps
the condensation temperature/pressure constant within preset limits (Air-Cooled).
Calibrated pressure :
DRYPOINT RA 80-160
R 404 A
Start 20 barg (45°C) - Stop 16 barg (36°C) - Tolera nce ± 1 bar
DRYPOINT RA 180-360
R 404 A
Start 20 barg (45°C) - Stop 18 barg (40°C) - Tolera nce ± 1 bar
PV1 : DRYPOINT RA 400-720 Fan control pressure switch located on the pushing side on the compressor. It keeps
the condensation temperature/pressure constant within preset limits (Air-Cooled) – Low Speed.
Calibrated pressure : R 404 A
Start 21 barg (47°C) - Stop 18 barg (41°C) - Tolera nce ± 1 bar
PV2 : DRYPOINT RA 400-720 Fan control pressure switch located on the pushing side on the compressor. It keeps
the condensation temperature/pressure constant within preset limits (Air-Cooled) – High Speed.
Calibrated pressure : R 404 A
Start 23 barg (51°C) - Stop 20.5 barg (46°C) - Tole rance ± 1 bar
5.14. Safety thermo-switch T
s
1
2
P
Q
S
0
0
0
5
To protect the operating safety and the integrity of the dryer, a thermo-switch (TS)
is installed on the refrigerant gas circuit. The thermo-switch sensor, in case of
unusual discharge temperatures, stops the refrigerating compressor before it is
permanently damaged.
Manually reset the thermo-switch only after the nominal operating conditions have
been restored. Unscrew the relative cap (see pos.1 in the figure) and press the
reset button (see pos.2 in the figure).
TS setting : temperature 100 °C (+2 / -2 °K)
5.15. Compressor crankcase heater (DRYPOINT RA 180-720)
At low temperatures oil can more easily be mixed with the refrigerant gas. So, when the compressor starts, oil can be
drawn into the refrigeration circuit and liquid hammering could occur.
To prevent this, an electrical resistance heater is installed in the suction side of the compressor. When the system is
powered and the compressor is not running, this heater keeps the oil at the correct temperature.
This heater is controlled by a thermo-switch which prevents overheating the oil.
NOTE : The heater must be powered at least a couple of hours before the start up of the refrigeration compressor.