Weighing method: The most accurate charge method is to actually weigh the weight of the refrigerant (refrigerant gas R134a, Refrigerant gas R410a, refrigerant r1234yf etc)added to the system.
This method can only be used when the required charge is known to the system and the system requires full charge, usually as described in the overall device.
Mirror method: The most common way to determine whether the refrigerant charge of the system is appropriate is to use the mirror in the liquid tube. Because the pressure of the liquid refrigerant is important for the control of the expansion valve. When a transparent liquid refrigerant flow is seen from the mirror, the system can be considered properly filled. If you see bubbles or flashes, it usually indicates that the refrigerant is not sufficient. Remember, if there is no liquid only steam, the view mirror is also transparent.
Refrigeration encyclopedia public number tips, when the system is properly charged, the mirror can also see bubbles or flash phenomenon, because the resistance in the liquid pipe in front of the mirror produces a pressure drop, resulting in refrigerant flash.
For example: in a cold storage suddenly change the fan speed can easily make the condensation temperature change 5.5 degrees C to 8 degrees C, at this time the liquid temperature in the receptacle will be higher than the corresponding saturation temperature of the changed condensation pressure, at this time will produce evaporation until the liquid temperature again drops to the saturation temperature below the evaporation. There may be different charging requirements under different operating conditions. When the air-cooled system operates at low temperatures, it usually controls the condensing pressure required by the system to submerge part of the condenser lines that flood the refrigerant. In this case, in summer, the mirror looks transparent and the refrigerant required is doubled in order to function properly at low temperatures.
Although the Refrigeration Encyclopedia public suggests that the mirror is a useful facility in determining the appropriateness of the system charge, we cannot rely entirely on the mirror as the sole basis for judging the system charge, and we must also carefully analyze the system performance. Level meter: In some systems, the reservoir has a level test port. If the charge has been reached, slightly open, the test port has a liquid refrigerant appear, if the test port only refrigerant vapor appears, then the charge is insufficient.
Larger tanks may be equipped with float indicators to indicate the level of fluid in the reservoir, which is very similar to the gasoline tank construction used in cars.
Method by Confirming refrigerant overcooling: For small systems, if there is no other easy means of checking refrigerant charge, the refrigerant charge can be determined by measuring the excess of the condenser outlet liquid. When the unit is operating under stable conditions, the temperature of the condenser outlet fluid pipe is compared with saturation (corresponding to the condensing pressure). This provides a comparison of the condensing temperature with the temperature of the fluid flowing from the condenser.
Continue to charge until the tubing temperature is 3 degrees C lower than the condensing temperature at the maximum load. Overheating method: A small unit system with capillary tubes can be used to determine whether the charge is appropriate. If there is an suction service port and the suction pressure can be measured, the difference between the temperature of the suction pipe from 0.15m of the compressor and the temperature on the evaporator tube at the midpoint of the evaporator (not on the evaporator fin) is determined as the difference in overheating. Under the normal operation conditions of the unit, continue to charge until the overheating measured by the above method is about 20 degrees to 30 degrees, such as when the overheating degree is close to 40 degrees, indicating that the charge is insufficient.