Accurate fluorine addition method for air conditioning maintenance

Accurate fluorine addition method for air conditioning maintenance Adding fluoride is a basic skill in air conditioning maintenance, and it is also a highly technical job. The following are some of the experiences that colleagues have explored in the maintenance practice, and discuss with readers.

　　 1. Prerequisites for accurate fluoride addition

　　 1. The air conditioner to be repaired must meet its conditions of use and installation standards.

　　 2. The air-conditioning control system and executive components to be repaired must be normal; the piping system must have effectively eliminated air, moisture, blockages, leaks, etc.; the filter and the internal and external heat exchangers should be clean and well ventilated.

　　 3. Maintenance tools and materials must be qualified.

　　 4. Strictly operate according to the fluoride process.

　　 2. The basis and method of accurate fluoride addition

　　 1. Quantitative fluorine addition: Connect the three-way valve, pressure gauge, fluorine hose, fluorine bottle or vacuum pump to the process port of the three-way stop valve. After fluorine was released and vacuumed, fluorine was added slowly. Weigh with a more accurate measuring tool such as a platform scale. When the reduction of fluorine in the fluorine bottle is equal to the standard fluorine addition on the air conditioner nameplate, close the fluorine bottle valve.

2. Measuring current: set the air conditioner in the cooling or heating high-speed air condition (the inverter air conditioner is set in the test operation condition), and observe the change of the clamp ammeter while adding fluorine at the process port of the low pressure shut-off valve. When it is close to the nameplate of the air conditioner When calibrating the rated working current value, close the fluorine cylinder valve. At this time, let the air conditioner continue to operate for a period of time. When the room temperature is close to 27°C in the cooling state or 20°C in the heating state, consider the factors affecting the rated operating current such as the air temperature of the outdoor unit and the voltage of the power grid. The amount of fluorine makes it reach the rated working current value, so that fluorine can be added accurately.

The reason for fine-tuning is because the rated working current value calibrated on the nameplate of the air conditioner is the data tested by the air conditioner manufacturer under the following conditions: refrigeration state, high-speed fan fan when the power supply voltage is 220V or 380V, indoor air temperature 27℃, outdoor unit air temperature 35℃; heating status, high-speed fan fan when power supply voltage is 220V or 380V, indoor air temperature is 20℃, outdoor unit air temperature is 7℃.

3. Pressure measurement method: put the air conditioner in a cooling high-speed wind state (in winter, when heating needs to add fluoride, set the air conditioner in a forced cooling state or place the room temperature sensor in warm water at about 27°C to simulate the summer temperature so that the air conditioner is in Operate in refrigeration state). At the process port of the low pressure shut-off valve, observe the low pressure of the vacuum pressure gauge while adding fluorine. When the low pressure is 0.49MPa (summer) or 0.25MPa (winter), close the fluorine cylinder valve. Then consider the factors that affect the low pressure pressure, such as the air temperature of the outdoor unit and the size of the indoor cooling load, and fine-tune the amount of freon and the gauge pressure to achieve accurate fluorine addition.

The reason for fine-tuning is that the low pressure is directly proportional to the indoor cooling load, that is, the greater the cooling load, the higher the pressure, and vice versa; the fluorination process port and nearby pipelines are installed outdoors, and their pressure and evaporation temperature are affected by the outside air temperature. The influence is great. The actual pressure and evaporating temperature of the indoor heat exchanger are higher in summer and lower in winter. In practice, when the fan has high-speed wind and the indoor temperature is 27℃, the low-pressure pressure data is shown in the attached table.

4. Observation method: Set the air conditioner to operate under high-speed air condition for cooling or heating. When the amount of fluorine is accurate, the temperature difference between the inlet and outlet of the indoor heat exchanger 10cm is: greater than 12°C during cooling and greater than 16°C during heating ; During cooling, all indoor heat exchangers are condensed, the evaporation sound is even and low, the outdoor shut-off valve is condensed, the condensation drips continuously in summer, the connection between the indoor heat exchanger and the capillary tube is free of frost or dew, etc.; when heating, indoors The wall temperature of the heat exchanger is greater than 40°C.

　　 In the actual maintenance, when the inverter air conditioner has a high requirement for the accuracy of the fluoride amount, or the fixed frequency air conditioner needs to be vacuumed due to the refrigeration pipeline system, the quantitative fluoride method should be adopted. If the piping system needs to be supplemented with fluorine, it is advisable to use the method of measuring current as the main, measuring gauge pressure as the supplement, and taking into account the observation.