Midea LSBLG255/MZ, Техническое и сервисное руководство

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DX type water-cooled screw chiller (PCB Control) MCAC-CTSM-2014-03
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triple evacuation method is recommended and is particularly helpful if the vacuum pump is unable to
obtain the desired 130Pa of vacuum. The system is first evacuated to approximately 660Pa (=5mmHg).
Dry nitrogen is then added to the system to bring the pressure up to zero.
Then the system is once again evacuated to approximately 230Pa(=2mmHg). This is repeated three
times. The first pull down will remove about 90% of the non-condensable, the second about 90% of that
remaining from the first pull down and, after the third, only 0.2% non-condensable will remain.
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Checks on refrigerant charge
To verify if the unit is operating with the correct refrigerant charge, perform the following checks.
1. Run the unit at maximum operating load.
2. Check the leaving chilled water temperature to be between 6~8°C.
3. Check the entering cooling water temperature to be between 25 and 32°C.
4. Under the above mentioned conditions verify the following items.
a) The sub-cooling to be between 4 and 6°C
b) The difference between leaving water temperature and evaporating temperature to be in 4~6°C
range.
c) The difference between condensing temperature and condenser leaving water temperature to be in
0.2~3°C range.
e) The evaporator refrigerant level slightly laps last tubes row by checking the sight glass installed on
each evaporator for a visual inspection.
f) The condenser refrigerant level to be included between the condensing and the sub-cooling sections
by checking the sight glass installed on each condenser for a visual inspection.
5. Verify the sight glass on the liquid piping to be fully charged. If one of the above parameters exceeds
the limits, unit may require an additional refrigerant charge.
Note: Refrigerant removing and drain operation must be performed by qualified personnel using correct
material. Inappropriate maintenance could lead to refrigerant or pressure loss. Do not discharge the
refrigerant or the lubricant oil into the environment. Always use a proper recovery system.
Refer to Physical Data tables supplied in the IOM manual book). Immediately ahead of orifice baffle (see
Fig.) is a factory-installed liquid line service angle valve. Each angle valve has a1 5/8-in. threaded
connection for charging liquid refrigerant. Connect the refrigerant drum to the gauge port on the liquid
line shutoff valve and purge the charging line between the refrigerant cylinder and the valve. Then open
the valve to the mid-position.
Turn on both the cooling tower water pump and chilled water pump and allow water to circulate through
the condenser and the chiller.
IMPORTANT: When adding refrigerant to the unit, circulate water through evaporator continuously to
prevent freezing and possible damage to the evaporator. Do not overcharge, and never charge liquid
into the low-pressure side of system.
If the system is under a vacuum, stand the refrigerant drum with the connection up, and open the drum