FRIULAIR ACT ES 20-500 User Maintenance Manual And Spare Parts Download

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Technical description

ACT ES 20 – 500

23 – EN

7.9 Hot gas by-pass valve

This valve injects part of the hot gas (taken from the discharge side of the compressor) in the pipe between
the evaporator and the suction side of the compressor, keeping the evaporation temperature/pressure
constant at approx. +2 °C. This injection prevents the formation of ice inside the dryer evaporator at every
load condition.

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)]

4 mm

5/32 in.

7.10 Refrigerant pressure switches LPS – HPS – PV

As operation safety and protection of the dryer a series of pressure switches are installed in the gas circuit.

LPS :

Low-pressure protection device on the suction side of the compressor, trips if the pressure drops
below the pre-set value. The values are automatically reset when the nominal conditions are
restored.

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 :

This high-pressure controller device, located on the 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 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 located at the discharge side of compressor. It keeps the condensing
temperature/pressure constant within preset limits.

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)]

7.11 Compressor crankcase heater

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.

ACT ES 200-500 3phase - For short periods of inactivity, (max 2-3 days) we recommend that
power is maintained to the dryer and the control panel. Otherwise, before re-starting the
dryer, it is necessary to wait at least 2 hours for the compressor crankcase heater to heat
the oil of the compressor.