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What about the refrigerant leak in the laboratory freeze dryer?

Technical Knowledge 2019-04-15 23:06:08
Refrigerant, also known as refrigerant, is commonly known as snow in some areas of the South. It is a working substance that continuously circulates in a refrigeration system and undergoes its own state change to achieve refrigeration. The refrigerant absorbs heat in the evaporator by heat of a cooling medium (water or air, etc.), and transfers heat to the surrounding air or water in the condenser to condense.

Refrigerant leakage in laboratory freeze dryers is a common occurrence. How to solve this situation? First, use the visual method to open the machine box to observe the inside of the machine. Since the refrigerant is running, there will be compression.

The lubricating oil is mixed inside. If the Freon leaks, the lubricating oil will be taken out. If you look at the inside of the machine carefully, if there is a sheet of oily dirt, it is likely to be the leaking point and then check the capillary copper tube inside the machine. That is, those thin copper tubes and process tubes of less than 6 mm have no breakage. After passing the above basic inspection, mark the suspected place.

The lubricating oil is mixed inside. If the Freon leaks, the lubricating oil will be taken out. If you look at the inside of the machine carefully, if there is a sheet of oily dirt, it is likely to be the leaking point and then check the capillary copper tube inside the machine. That is, those thin copper tubes and process tubes of less than 6 mm have no breakage. After passing the above basic inspection, mark the suspected place.

Then it is necessary to confirm the leak point by adding a certain pressure of inert gas. Under the condition of condition, it is better to use nitrogen to maintain the pressure. If there is no nitrogen, the gaseous Freon is also used. It is strictly forbidden to check the leak with oxygen pressure. It is to die. The screaming of the gaseous freon, the big brother does not know, that is, the freon cylinder is standing upright, the gaseous freon is coming out from the upper stop valve, and the liquid freon is put in the downward direction of the cylinder stop valve. The intuitive appearance of zui is that the refrigerant pressure gauge is zero. Leakage of fluorine must first find a leak. When holding pressure, the gas should be slowly added at the beginning, and the pressure of the refrigerant on the cold dryer should be observed while pressing (the small cube is only the refrigerant low pressure meter, and the high pressure and low pressure two refrigerant tables of 15 cubic meters or more) are pressurized to 0.2Mpa2.0kgf. Temporarily stop, then carefully listen to the sound inside the machine, if there is any, you can find the leak point where the sound is located. If not, continue to pressurize to 0.4-0.5Mpa. Then find a sponge and apply soapy water. Check the suspected area first, then check all the connected inside the machine.

If the leak is not found by the above method, then unfortunately, it is very likely that the leak in the evaporator leaks inside the evaporator is more troublesome. First, it must be confirmed. It can be confirmed by disconnecting the evaporator and the refrigeration system, and then holding the pressure separately. If the pressure is reduced after the pressure is maintained, it can be determined.

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

After finding the leak point of the dryer, it is the difference of the leak point. If the bell mouth loosens these leak points, it only needs to be tightened by the wrench. If it is the leak point of the copper tube welding type, it needs to use the brazing. weld. Brazing trap is a common skill in the refrigeration repair industry. The so-called brazing is to use oxygen and acetylene flames to heat the low-silver electrode and the required compensation.

The welding part, the method of melting the welding rod and the repairing welding part to block the leaking point. Brazing should first release the pressure of the refrigeration system, then use the brazing gun to first open the acetylene, add oxygen after the point, slowly adjust the ratio of oxygen and acetylene gas, make the flame into a neutral flame-oxidation flame, and then heat The required weld and silver electrode dissolve the two together. The specific method requires the operator to master through certain training. After the leak is processed, the system needs to be pressured again to confirm the success of the trap welding.

After the trapping is completed, the system needs to be evacuated, and then the specified quality liquid freon is added (the specific quantity refers to the basic configuration table) and the refrigerant should be reserved from the cold dryer. Some dosing needle valves are added. For larger machines, the fluorination should be added first from the high pressure filling port. If the specified dosage cannot be added at one time, wait for the prescribed dose from the low pressure port after starting the machine.

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