Start-Up - Midea LSBLG MCF Series Technical & Service Manual

Flooded type water cooled screw chiller (MIC)
2.

Start-up

Before starting the unit, the following performance parameters need to be inspected:
(1) High/low voltage value of the system. If the unit will be shut down and waterless for a long time, the
liquid and gas of the system must 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 gauge pressures, of which 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 relative pressure. The types of
refrigerants indicated in different pressure gauges might differ.
Refrigerant
Temperature ℃
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, 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 a failure in oil heating might lead to poor lubrication of the unit. The optimum
working temperature for current types of lubricating oil is generally around 40℃.
[Table 1]
R134a Refrigerant Pressure (Gage
0
5
10
15
20
25
30
35
40
86
MCAC-CTSM-2018-1
In shutdown status, the high and
low voltages shall be the same and
equal to the saturation pressure
corresponding to
temperature.
Pressure) MPa
0.19
0.25
0.32
0.39
0.47
0.57
0.67
0.79
0.92
the current