Flooded type water cooled screw chiller (PCB Control)
91
2.
Start-up
Before start-up of the unit, the following performance parameters need to be inspected:
(1) High/low voltage value of the system. For the unit shut down and waterless in a long term, the liquid
and gas of the system shall be equivalent and close to the saturation pressure corresponding to the
current ambient temperature. The correlation of saturation temperatures and pressures (the
pressures in the list are gage pressures, among which, the atmospheric pressure is 0.1MPa) of R22
and R134a refrigerant is shown in table 1:
In the pressure gauge scale, taking the right figure for example: the values outside of the black circle are
pressure values (unit: bar), and the values of the red, blue and green circles indicate saturation
temperatures of refrigerants R404A, R22 and R134a respectively under the relative pressure. The types
of refrigerants indicated in different pressure gauges might differ.
[Table 1]
If the high/low voltage deviates much from the saturation pressure corresponding to the current
temperature (more than 2bar), leakage or insufficient refrigerant is likely in the system.
(2) Inspect the unit for normal heating
Before start-up, it is necessary to inspect whether the oil heating in the unit is available, and whether the
oil heater does not work when there is oil for heating but no power supply. It is particularly important in
winter when the temperature is low and the failure of oil heating might lead to poor lubrication of the unit.
The optimum working temperature for current types of lubricating oil is generally around 40
℃
.
Refrigerant
Temperature
℃
R134a Refrigerant Pressure (Gage
Pressure) MPa
0
0.19
5
0.25
10
0.32
15
0.39
20
0.47
25
0.57
30
0.67
35
0.79
40
0.92
In shutdown status, the high and
low voltages shall be the same and
equal to the saturation pressure
corresponding
to
the
current
temperature.
