【 Weak current College 】 chillers mainly parts maintenance

1. maintenance of the chiller compressors
(1) Visual inspection of the compressor
Checking method: Visual
Check criteria: check chiller compressors and export valve connection reliability, and whether there is a leak; testing should be aware of the compressor running voice to determine whether there is an exception.

(2) the voltage and current measurement
Measure tool: clip-on ammeter
With clip-on ammeter working voltage, current. When running the current measuring cables should be in the Centre of the measuring loop metrics: 380V running voltage range (± 10%), and run-current should not be greater than the motor nameplate of rated input current.

(3) measurement of insulation resistance
Measure tool: megohmmeter
Measurement method: power off the unit, with three megohmmeter detection compressor relatively resistance meets the standards. If the machine head of time is not enabled, you should first be set in the crankcase electric heating cycle
Still, oil heating unit, the unit oil cavity of freon evaporation, improve the accuracy of the measurement of resistance.
Measurements Note: no measurement under the vacuum State, prevent the insulating layer of insulation breakdown caused by the accident.
Measurement standards: compressor motor insulation standards for not less than 500 MB, the actual measurement value should be greater than 100 megohm is qualified, under the hot and cold insulation value is greater than 8 megohm is allowed to run.

(4) the method for the determination of the oil products:
Available from the chiller unit to extract the oil in a small frozen into the container, take a drop into acid reagent bottle observation of acidity, with a contrast ratio of color card. Consistent with a controlled than color card colors should not be replaced refrigeration oil.
Extract from the unit in a little frozen oil into the container, to minimize the exposure time in the air, and then use the PH test strip discriminant oil acidity. Comply with the requirements of oleic acid degree does not need to be replaced refrigeration oil, used oil blotting paper checks of impurity, carbon emission, or other impurities and should be replaced refrigeration oil.

2. maintenance of condenser
Maintenance tool: pipeline cleaning machine or chemical cleaning agents.
Maintenance: water cooled condenser with shell and tube water-cooled condenser, condenser cleaning and maintenance work
As very important, good cooling water quality should be maintained, cooling water chemical treatment should be conducted on a regular basis to ensure heat transfer tubes not scaling, maintenance can be divided into mechanical cleaning and chemical cleaning (refer to chemical cleaning procedures).
Mechanical cleaning methods:

1. shut down the cooling water and export the valve
2. detach the condenser and rear end cover
3. clean the condenser end cover, water Chamber cavity scaling and corrosion
4. pipe cleaner cleaning heat pipe
5. after washing with water, until you reach the standard, and then put the end cover
Maintenance standards: maintenance after water room, the overall heat transfer tubes visually clean, no apparent scaling wall

Notes: 1. what methods of cleaning, according to the condenser tube forms to identify and prevent damage to the Inner ribbed tube
2. uniform chemical cleaning must
3. the concentration of detergent and cleaning time to follow the manufacturer instructions for
4. rinse time must be clean, completely, without residue

3. maintenance of the evaporator
(1) check the frozen water and evaporator scaling, do a good sewage water exchanger
(2) detection of water side and refrigerant temperature difference between
(3) maintenance should open the evaporator bottom of sewage valve will impurities, sludge discharge. If necessary, remove the sewage valve, to increase the outfall
(4) in particular it should be noted that during the winter does not use water to prevent freezing damage caused evaporator
(5) to prevent dropping out of the sensor shall lead to induction of temperature is the temperature of the air instead of evaporator temperature, resulting in frequent low temperature alarm
(6) maintenance work can reference when sewage, the following steps:
1. run the water pumps in 10 minutes
2. in a outlet check water quality
3. According to the color of water, suspended solids, rust, etc., we recommend that users use mechanical cleaning or chemical cleaning
4. after cleaning, sewage valve open to most, sewage
5. row of net again pouring water, running for 30 minutes and then view a water, if necessary, then the job once

4. Unit piping and fittings maintenance
4.1 expansion valve of checking
Testing tools: surface contact thermometer
Checking method: check the expansion valve Junction has no traces according to overheat, compressor unit back to the gas side condensation level determines the unit run time expansion valve opening is appropriate, check that the sensor is loose, bundled with position sensor of the capillary is no wear and tear. On balance pipe connection nut, bolt do antirust protection valve.
4.2 as liquid mirror checks and drying filter replacement
Check tool: surface contact thermometer
Checking method: Visual inspection as liquid mirror display cases in the test strip judge system refrigerant of humidity, confirm the need to replace dry filter, surface contact thermometers for measuring the temperature difference is lower than before and after the filter, that filter clean 0.5 ℃.
Drying filter replacement method:
1. first close the high-pressure fluid, moving units exported angle valve and pumping systems for low-voltage side of the refrigerant (non-vacuum suction), and then locking unit
2. detection of drying filter pressure is lower than the adjacent 2.0kg/c © o, if you add refrigerant pipes to the parts of the emissions of gaseous refrigerant
3. diagonal release of drying filter end cap screws (release note difference before to prevent temperature difference of water into the system), emptying refrigerant then quickly change the old filter, clean and dry the filter cylinder internal, get a new filter, add a small cylinder of port sealed refrigeration oil.
4. vacuum supplement a little refrigerant, open front closed valve
Maintenance standards: sight glass indicates in a dry area is less than the difference before and after the dryer 0.5℃
4.3 electrical components maintenance
Testing tools: Multimeters and selection of ampere meter
Maintenance method:

1. check and fastening electric line terminal, check the contactor contacts of burning conditions
2. the contact points with canvas and grinding to remove oxide, if severe, it is recommended that you replace the burns
3. check if the solenoid valve, such as 4-way reversing valve, solenoid valve, the unit loading and unloading of solenoid valve, solenoid valve for spraying liquid, electric heating and other actions properly, or to replace or repair.
Maintenance standards: contact clean, no Burns oxides, Sync contact, non-ripple noise.
4.4 check all safety devices
Maintenance methods: inspection and testing of all security devices (thermal protector, flow switch, pressure switches, and other protection devices), check the tuning parameters
Maintenance standards: thermal protection with good retention, wiring intact, flow switch, open and close motion normal, high and low voltage switch action in 24.5 ± 0.5Bar.