Screw chiller maintenance, including daily maintenance and regular overhaul can ensure the long-term normal operation of the unit. For screw chiller, there should be operation records, record the operation of the unit, and establish maintenance technical files. Complete technical information helps to find hidden trouble and take early measures to prevent the occurrence of discharge defects. Next central air conditioning maintenance editor to share with you the central air conditioning screw chiller maintenance content are mainly.

1. Oil change and filter dryer (required)

1. Preparation: Check whether the compressor lubricating oil is preheated for more than 8 hours, and the oil heater is energized for at least 8 hours before the test run to prevent frothing of the frozen oil when starting. If the ambient temperature is low, the oil heating time needs to be relatively longer. When starting at low temperature, due to the large viscosity of lubricating oil, it will be difficult to start and the compressor loading and unloading is poor. Generally, the low temperature of lubricating oil needs to reach 23℃ or more before it can be operated, started, and recorded operating parameters to analyze the problems existing before and now. Do your homework.

(1) Short-circuit the high-low-voltage differential switch (do not adjust the differential pressure switch, you can directly short-circuit the two wires). When the machine is running at full load. Close the Angle valve (pay special attention to restore the differential pressure switch after refrigerant recovery).

(2) Press the emergency switch or turn off the power when the low pressure of the machine is less than 0.1MP. Because there is a check valve at the compressor exhaust port, the refrigerant will not return to the press, but sometimes the check valve may be closed loosely, so close the stop valve of the press exhaust while pressing the emergency switch.

Second, when the above work is completed, turn off the main power supply. Carry out the following processes:

1, the oil, the refrigerant oil in the system under the pressure of refrigerant gas spray speed is very fast pay attention to health do not spray outside. Discharge refrigerant while discharging oil and open high pressure gauge stop valve.

2. Clean the oil tank and oil filter. Open the cover of the oil tank and clean the dirty gauze of the oil tank with dry gauze. Then pour the spent frozen oil into the fine gauze. Open the oil filter with a big wrench and clean it with waste oil.

3. Replace the refrigerant filter

(1), the refrigerant filter core has 3 in the replacement speed should be fast, to prevent the contact time with the air is too long to absorb too much water.

(2), the filter is packaged in cans, and it is protected during transportation. Once the packaging is damaged, it is invalid.

Three, vacuum refueling

According to the compressor structure, refueling from the high pressure side, because the high pressure and low pressure chamber of the compressor are not directly connected, it is difficult to return to the oil tank from the low pressure refueling oil. We usually vacuum the oil from the low pressure side and suck the oil from the high pressure side.

(1) About vacuuming, the purpose is to extract the water and air in the system. When the vacuum pump is sealed or aging is more serious, and the vacuum degree does not meet the requirements, then it is useless to evacuate such a vacuum pump for a long time.

(2) Regarding vacuum damage, when the vacuum is evacuated to negative pressure, the Angle valve is opened to release a little refrigerant from the condenser, which damages the vacuum of the system

(3) Note: liquid supply solenoid valve, because the solenoid valve is also closed when the machine is closed, so when the refrigerant oil is added, the differential pressure switch is restored. Turn on the power to preheat and power on the solenoid valve (can be connected to the oil heater)

(4) Fill the blind tube with oil: replace the waste frozen oil for the blind tube.

Four, safety valve calibration

The condenser and evaporator on the screw chiller belong to the pressure vessel. According to the regulations, the safety valve should be installed on the high-pressure end of the unit, that is, the condenser body. Once the unit is in an abnormal working environment, the safety valve can automatically relieve pressure to prevent the harm caused by high pressure to the human body. Therefore, the regular verification of the safety valve is very important for the safety of the whole unit.

Five, refrigerant charging

If there are no other special reasons, the general unit will not produce a large number of leaks. If a certain amount of refrigerant leaks due to improper use or after maintenance. You need to refill the refrigerant. When charging refrigerant, pay attention to the brand of refrigerant used in the unit.

6. Preheating

Power on preheating at least to heat the oil to 23℃ or above to start running.

Seven, cleaning and maintenance

Open the condenser to clean, clean the system of debris, welding slag, dust, some anti-rust coating, etc. General high pressure pressure corresponding to the saturation temperature (condenser water temperature), when the temperature difference is greater than 3-5 degrees, need to clean the condenser.

It is not recommended to frequently clean the condenser with chemical potion, which has prevented the corrosion of the condenser perforation and leakage of fluorine, so it is very important to maintain the cleaning and softening of the circulating water. It should be noted that this point must be analyzed by professional water treatment experts.

Eight, maintenance points

1 The chilled water temperature is generally set at 7 degrees. (Anti-freezing protection is set to 4 degrees, when the weather is cool and the indoor load is too low, the water temperature may drop too fast and the machine has no time to stop, anti-freezing protection may occur, and the water temperature may drop too fast and the machine has no time to stop, and the anti-freezing protection can be set to 9 degrees).

2, the summer indoor load is too high when the boot may occur compressor overload failure. (At this time, the chilled water inlet valve should be properly turned off, and the compressor overload fault may occur when the indoor load is too high in summer. At this time, the chilled water inlet valve should be turned off (reduce the water flow rate, and open the water valve when the water temperature is below 15 degrees). Prevent high voltage or overload failure due to excessive load and low voltage for a long time). Long time too high, while reporting high voltage or overload failure).

3, the cooling water temperature is controlled between 25-35 degrees (when the weather is cool, when the weather is cool, the cooling water valve can be turned off to keep the cooling water above 25 degrees)

4, must record the machine operation data before starting, should check the power supply voltage imbalance can not be greater than 2% when the refrigeration system pressure is less than 5kg is not allowed to start, then the machine may leak fluorine, to prevent the compressor low pressure alarm when starting.