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How to Check the Refrigerant Charge?

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How to Check the Refrigerant Charge?

Issue Time:2021-09-16
 methods to test whether the refrigerant charge is appropriate

If the refrigerant is charged too little, it may cause frosting in the evaporator and affect the refrigeration effect. If the refrigerant is charged too much, the load of the compressor will increase, and the refrigeration equipment will be damaged in severe cases. We must control the refrigerant charge, the followings are methods to test whether the refrigerant charge is appropriate.

1. Pressure measurement

The temperature of the saturated vapor of the refrigerant corresponds to the pressure. If the evaporation temperature of the refrigerant is known, the corresponding evaporation pressure can be found. The gauge pressure value of this pressure is displayed by the high and low-pressure gauges. Therefore, according to the pressure value of the pressure gauge installed in the system, it can be judged whether the refrigerant charge is appropriate.

For example, the evaporating temperature of the air conditioner is 7.2℃, and the condensing temperature is 54.5℃. Check the corresponding table of saturation temperature and saturation pressure of R22 to determine its evaporation pressure value and condensing pressure value.

Looking up the table, we can see that the corresponding absolute pressure value of R22 at 7.2℃ is 0.53Mpa (5.3kg/cm2) and the corresponding absolute pressure value at 54.5℃ is 2.11Mpa (21.1kg/cm2). Convert this pressure to gauge pressure.

Use high and low-pressure gauges or composite pressure gauges to test the refrigeration system in fluorine charging. If the gauge pressure values of the high and low-pressure gauges meet the above range, it indicates that the refrigerant charge is appropriate; if the high and low pressures are both low, it indicates Insufficient charge; if the high and low pressures are both high, it indicates that the charge is too much.

The pressure measurement method is relatively simple and often works during maintenance, but the disadvantage is that the relative accuracy is not high enough.

2. Measuring weight

When filling freon, prepare a small scale in advance, but the refrigerant cylinder into a container, and then fill the container with cold water below 40°C (applicable to low-pressure charging refrigerant vapor for air conditioners). Write down the weight of the steel cylinder, warm water, and container before filling, and observe the pointers during the filling process. The charging can be stopped when the decrease of the refrigerant in the cylinder is equal to the required charging amount.

3. Measuring the working current

Use a clamp-type ammeter to measure the working current. When cooling, the ambient temperature is 35°C. The measured working current corresponds to the current on the nameplate. The higher the temperature, the corresponding increase in current, and the lower the temperature, the corresponding decrease in current. When the fan is normal and the heat dissipation signal of the two devices is normal, the current value measured according to the working condition of the air conditioner is compared.

4. Measuring temperature

Use a semiconductor thermometer to measure the temperature of the inlet and outlet of the evaporator and the outlet of the liquid collector to determine the refrigerant charge. The temperature difference between the inlet of the evaporator (150mm in front of the capillary) and the outlet is about 7-8°C, and the temperature at the outlet of the liquid collector should be higher than that at the outlet of the evaporator by 1-3°C.

If the temperature difference between the inlet and outlet of the evaporator is large, it indicates that the refrigeration capacity is insufficiently charged. If the frosting section of the suction pipe is too long or there is frosting near the compressor, it indicates that the refrigerant is charged too much.

In the process of refrigerant charging, not only the charging volume needs to be paid attention to, but also the correct operation steps must be strictly followed. If you want to learn more about refrigerant-related information and solutions after reading the above, you can contact FORTECH for professional advice.

As a professional manufacturer of refrigerants and fluoropolymers, we have accumulated rich manufacturing experience in this field. We have a professional production team that strictly implements each link of production in accordance with the standards, and is also equipped with a strict quality inspection system to provide customers with high-quality and safe products. We always put the needs of customers first and can provide customers with thoughtful one-stop services and develop effective solutions. If you are interested in our refrigerants, please contact us immediately!

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Fotech is a professional supplier and manufacturer of refrigerants and fluorine polymers over 20 years, distributing environmental friendly refrigerant, clean agent fire extinguishing agent, blowing agent, cleaning agent, and high performance new chemical materials...more>