What are the operating steps and methods of filling refrigerant in air conditioners?

A friend asked, what are the operating steps for filling refrigerant into the air conditioning pipeline? It depends on the circumstances under which you fill the pipeline with refrigerant.

1. If it is a new air conditioner, after the pipeline installation is completed, after the air tightness test, the pipeline system must be vacuumed before adding refrigerant. Then directly connect the pressure gauge to the operating valve (the split small unit has only one operating valve, and the multi-line has two valve operating interfaces. Both interfaces can be added when the machine is stopped, but the fluorine must be added at low pressure when the machine is turned on. )

2. If additional refrigerant is added during the operation (use) of the air conditioner, the pressure gauge must be connected to the low pressure point. At this time, you have to judge the high and low pressure interface of the system. When cooling, the liquid pipe is high pressure and the air pipe is low pressure. The opposite is true for heating. . When adding refrigerant, note that R22 refrigerant is a single refrigerant. When adding refrigerant, it can be added in a gaseous manner. R410A is a suspected azeotropic refrigerant mixed with two refrigerants. It must be added in a liquid manner (otherwise the composition will change). Pay attention to the slow speed on the low pressure side to prevent the press from returning liquid.

Now many inverter air conditioners use R410A and R32 refrigerants. Among them, R410A refrigerant is a HFCs refrigerant that is a mixture of two working fluids, R32 and R125, at a mass fraction of 1:1. Compared with R22, the condensing pressure of R410A is about 1.6 times that of R22. It is a high-pressure refrigerant and needs to improve the pressure strength of the system.

Compared with R410A, R32 refrigerant saturation pressure is about 2.5%~3% higher than R410A. Also note: R22 and R410A are different in composition and pressure, and the thickness of the copper tube of the machine is also different, so it is forbidden to mix the two refrigerants. Maintenance measuring instruments and quantitative refrigerant charging equipment should also be dedicated.

Safety Guidelines for R32 Refrigerant:

It is strictly forbidden to run the R32 system without vacuuming;

It is strictly forbidden to run the compressor without load when the valve is open;

It is strictly forbidden to remove the connecting pipe to check whether the compressor has suction and exhaust (whether gas is discharged from the small valve);

It is strictly forbidden to start operation without opening the valve;

It is strictly forbidden to use the compressor of the air conditioner to suppress leak detection;

It is strictly forbidden for the compressor to vacuum itself;

It is strictly forbidden to start and run under vacuum;

It is strictly forbidden to add different refrigerants or inferior refrigerants;

Recycling of refrigerant is strictly prohibited for more than 2 minutes (applicable to household appliances);

It is strictly forbidden to shield protective devices such as overload, exhaust, and overcurrent high and low voltage protection.

Additional points of multi-line central air-conditioning refrigerant:

★ Calculate the amount of additional refrigerant by calculating the actual pipe length of the system liquid piping. According to the calculation result, add refrigerant. Never add refrigerant arbitrarily based on operating current, pressure, temperature, etc. This is because the current, pressure, etc. change depending on the temperature, pipe length, and frequency.

★ When charging the refrigerant, you must use special tools such as an electronic liquid filling scale, a bifigure meter, and a filling hose. The amount of refrigerant added cannot be guessed at will. After the addition of refrigerant is completed, fill in the added refrigerant amount into the nameplate of the outdoor unit to facilitate future after-sales work. To avoid mixing of foreign oil, please use tools etc. according to the type of refrigerant. In particular, the instrument manifold, filling hose, and vacuum pump must never be shared with other refrigerants (R22, R407C, etc.).

★ For additional sealing of refrigerant, please add refrigerant from the liquid pipe in a liquid state. Only the standard refrigerant amount is enclosed in the multi-line group (the enclosed amount of pipe length is 0m). Please add refrigerant quantitatively according to the size and length of the liquid pipe. The calculation formula is as follows:

Take Mitsubishi Heavy Industries’ KX4 (410A) model as an example, the charge amount = the total length of the liquid pipe of Φ22×0.35+the total length of the liquid pipe of Φ19.1×0.25+ the total length of the liquid pipe of Φ15.9×0.17+Φ12.7 The total length of the pipe × 0.11 + the total length of the Φ9.5 liquid pipe × 0.054 + the total length of the Φ6.4 liquid pipe × 0.022 (kg). Pay attention to different brands to read the manuals of different brands, the formula is very different.

Suggestions for correct charging of refrigerant:

In fact, the weighing and filling method is the only true correct method, and it is suitable for any refrigeration system. The method is to weigh the weight of the refrigerant charged, and what needs to be done is to find out the amount or range of refrigerant that should be charged from the relevant information. This is not just an observation method, but a true filling method. As long as the manufacturer indicates the correct charging amount of the refrigeration equipment on the nameplate, after the system is completely dried and evacuated, a steelyard, electronic scale, dial scale or other weighing device can be used for weighing and charging.

Some people may say, can it be used to measure the current depending on the pressure? Yes, but the weighing is more reasonable, and the current measurement method has many drawbacks. such as:

If the condensing air volume is insufficient, the high pressure will be very high, and if the system's evaporating air volume is insufficient, the low pressure will be very low, which will cause the pressure fluctuation filter to be dirty; the main power supply voltage is too low; the main power supply voltage is too high; the refrigerant is charged in cold weather; Charging refrigerant will cause the current to be too large or too small. Therefore, based on the above reasons, major manufacturers recommend the use of weighing additional refrigerant.