ICP iDRY iRDP CT 100, Instructions For Installation And Operation Manual

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Technical description
iDRY iRDP CT 20-500 17
8.9 Hot-gas bypass valve
At partial load, the valve directly returns a part of the hot gas to the suction line of the refrigerating compressor. The
evaporation temperature and the evaporation pressure remain constant.
ADJUSTMENT
The hot gas by-pass valve is adjusted during the manufacturing testing phase.
As a rule no adjustment is required; anyway if it is necessary the operation
must be carried out by an experienced refrigerating engineer.
WARNING
the use of ¼” Schrader service valves must be justified by a real malfunction
of the refrigerating system. Each time a pressure gauge is connected, a part
of refrigerant is exhausted.
Without compressed air flow through the dryer, rotate the adjusting screw
(position A on the drawing) until the following value is reached:
Hot gas setting :
R134.a pressure 31.9 psig (+ 1.45 / -0 psi) [2.2 barg (+0.1 / -0 bar)]
R407C pressure 68.2 psig (+1.45 / -0 psi) [4.7 barg (+0.1 / -0 bar)]
A
4 mm
5/32 in.
+
-
V
L
Y
0
0
0
1
8.10 Refrigerant pressure switches LPS – HPS – PV
To ensure the operational reliability and the protection of the dryer, a series of pressure switches are installed in the
gas cycle.
LPS : Low-pressure guard on the suction side of the compressor, which is triggered when the pressure drops below
the predetermined value. The values are reset automatically as soon as the nominal conditions are re-
established.
Calibrated pressure :
R 134.a Stop 10.2 psig (0.7 barg) - Restart 24.7 psig (1.7 barg)
R 407 C Stop 24.7 psig (1.7 barg) - Restart 39.2 psig (2.7 barg)
HPS : The high-pressure control unit on the discharge side of the compressor is activated when the pressure
exceeds the predetermined value. It has a manual reset button on the control itself.
Calibrated pressure :
R 134.a Stop 290 psig (20 barg) - Manual reset P<203 psi (P<14 bar)
R 407 C Stop 435 psig (30 barg) - Manual reset P<334 psi (P<23 bar)
PV : Fan control pressure switch which is installed on the discharge side of the compressor. It keeps the
condensation temperature and pressure constantly in the range of the preadjusted limit values
Calibrated pressure : R 134.a Start 160 psig (+7.25 / -0 psi) [11 barg (+0.5 / -0 bar)]
Stop 116 psig (+0 / -7.25 psi) [8 barg (+0 / -0.5 bar)]
R 407 C Start 261 psig (+7.25 / -0 psi) [18 barg (+0.5 / -0 bar)]
Stop 203 psig (+0 / -7.25 psi) [14 barg (+0 / -0.5 bar)]
8.11 Compressor crankcase heater (iRDP CT 200-500 3phase)
At low temperatures, the oil can more easily intermix with the refrigerant gas. When the compressor starts, oil can be
drawn into the refrigeration cycle, leading to "hydraulic shocks".
To prevent this, a resistance heater is installed in the suction side of the compressor. When the system is connected
with the electric mains and the compressor is idle, the heater will keep the oil at the correct temperature.
This heater is controlled via a temperature switch which prevents the overheating of the oil.
Note: The heater must be connected to the mains at least a few hours prior to the start-up of the refrigerating
compressor.