How to deal with the problem of refrigerant leakage from the freeze dryer

How to deal with the problem of refrigerant leakage from the freeze dryer

Leak detection points require patience, carefulness and certain methods. The specifics are as follows: first use the visual inspection method to open the box panel of the machine to observe the inside of the machine, because the refrigerant will be compressed when it is running.

Engine oil is mixed in. If the Freon leaks, the oil will be brought out. Then carefully observe the inside of the machine. If there are flakes of oil stains, it is likely to be the leakage point and then check the capillary copper tube inside the machine. That is, whether the thin copper tubes and craft tubes below 6 mm are broken. After passing the above basic inspections, mark the suspected areas.

Then you need to fill in a certain pressure of inert gas to confirm the leak. If possible, it is best to use nitrogen to maintain the pressure. If there is no nitrogen, use gaseous freon. It is strictly forbidden to use oxygen to maintain pressure to check the leak. What is gaseous freon? Brother doesn't know this. It is to put the freon cylinder upright, and the gaseous freon comes out from the upper shut-off valve. On the contrary, put the cylinder shut-off valve downwards and it is liquid freon. The most intuitive appearance is that the refrigerant pressure gauge is zero. Fluoride leakage must first find the leakage point. When maintaining the pressure, add gas slowly at the beginning, and observe the pressure of the refrigerant gauge of the refrigeration dryer while pressurizing (the small cube has only a refrigerant low pressure gauge, and there are two high and low pressure refrigerant gauges above 15 cubic meters) when the pressure reaches about 0.2Mpa2.0kgf Stop temporarily, and then listen carefully to see if there is any air leak inside the machine. If there is, you can find the leak according to where the sound is. If not, continue to pressurize to 0.4-0.5Mpa. At this time, find a sponge and dip it in soapy water. Check the suspected areas first, and then check all the connections (copper nuts) inside the machine.

If the leak is still not found through the above methods, unfortunately, it is very likely that the evaporator leaks and it is troublesome to handle the evaporator leak. It must be confirmed first, which can be confirmed by disconnecting the evaporator and the refrigeration system, and then separately maintaining the pressure. If the pressure is found to decrease after the independent pressure, it can be determined.

Another relatively simple method is to open the compressed air inlet. If the pressure of the refrigerant pressure gauge rises after a period of time, it can be sure that the refrigeration system is connected to the air system because the exchange part of the w* is the evaporator. Therefore, the internal leakage of the evaporator can also be determined.

After finding the leaking points of the dryer, the leaks are corrected. According to the difference of the leaking points, for the loosening of the horns, you only need to tighten them with a wrench. If it is a copper pipe welding type of leaking point, you need to use a braze. weld. Brazing is a common skill in the refrigeration maintenance industry. The so-called brazing is to use oxygen and acetylene flames to heat the low-silver electrode and repair it.

Welding part, the method of fusing the welding rod and the repair welding part together to block the leakage point. When brazing, the pressure of the refrigeration system should be vented to zero, and then use the brazing torch to open the acetylene first, add oxygen after ignition, and slowly adjust the ratio of oxygen to acetylene to make the flame a neutral flame-oxidation flame, and then heat The required welding part and the silver electrode make the two melt together. The specific method requires the operator to pass certain training to master. After the leaks are processed, the system needs to be pressured again to confirm whether the leak repair welding is successful.

After the leak is completed, the system needs to be evacuated, and then the specified quality liquid Freon (refer to the basic configuration table for the specific quantity) and the refrigerant should be reserved from the cold dryer.

Some dosing needle valves are added. For larger machines, fluoride should be added from the high-pressure filling port first. If the prescribed dose cannot be filled at one time, add fluoride slowly from the low-pressure port to the prescribed dose after starting the machine.