Don't blindly repair the refrigeration compressor if it fails to contact the manufacturer is the best policy

Don't blindly repair the refrigeration compressor if it fails to contact the manufacturer is the best policy

The environmental temperature and humidity test box is mainly used for product temperature, humidity alternating and high and low temperature rapid alternating cycle tests, and its purpose is to detect the reliability of products under high and low temperature impact tests. The general temperature range is between -70°C and +180°C. According to the product process requirements, a program can be set to control the temperature and humidity changes. Because the temperature required for the refrigeration part is low, the principle of cascade refrigeration is usually adopted. .

Do not blindly repair the refrigeration compressor if it fails to contact the manufacturer is the best policy

Recently, the author’s company has a failure of an environmental test chamber imported from the United States. The failure phenomenon is: half a minute after starting up, an oil pressure alarm is reported. The refrigeration compressor is 4B3139L-2NC, and the German Bitzer semi-closed piston refrigeration compressor has its nameplate. The parameters are as follows:

Do not blindly repair the refrigeration compressor if it fails to contact the manufacturer is the best policy

When the problem occurs, our maintenance personnel initially judged based on past experience that it may be a failure of the refrigeration compressor oil pump assembly, and the refrigeration compressor has a high and low pressure protection device. The high pressure protection value of the water-cooled type is: 18kg/cm2, oil pressure protection Device: mechanical type is MP54, brand name is: DANFOSS, protection pressure difference: less than 0.7bar, with a delay of 90±10 seconds, oil pressure difference is 2.5-3 kg/cm2, according to the oil pressure of the two-stage refrigeration compressor The difference △P=oil pressure outlet pressure-intermediate pressure (intake port pressure), it seems that our judgment is correct. At the same time, we also observed the oil window of the refrigeration compressor, and found that the oil level is not obvious and almost observed in the shutdown state The oil level was not reached, and then we forced to start the operation. After turning on the refrigeration compressor for a few minutes, we observed foam at the oil level from the oil window. When it was confirmed again that the lubricant was seriously insufficient, we analyzed it carefully and found that the lubricant in the system was missing , Where can I go? When the angle valve on the intercooler pipeline is opened, there is lubricating oil that leaks out with the refrigerant, so everyone agrees that the fluorine oil separator is faulty. Because the function of the fluorine oil separator is mainly to separate the Freon and the refrigerated lubricating oil in the refrigerant system, and then re-inject the recovered lubricating oil into the oil pan at the bottom of the compressor through the oil return pipe. So we replaced a new set of fluorine oil separator without contacting the manufacturer, the model is HENRY S5190, the brand is Emerson, but when we restarted after the simple replacement, we were dumbfounded. It does not start at all, and the failure phenomenon is not eliminated. The angle valve of the intercooler has a mixture of lubricating oil, refrigerant, and water discharged at the same time.

As a last resort, we had to find a domestic sales and service company of U.S. Environmental Testing. When we communicated this phenomenon with the equipment manufacturer, the manufacturer re-analyzed and located the fault. The manufacturer believed that "this compressor is a semi-hermetic refrigeration compressor. Because BITZER compressors and condensing units are divided into high-temperature and low-temperature motor types. Low-temperature compressors and units cannot be used in occasions where the evaporation temperature is above -5°C, and high temperature should be used when the storage temperature is 0°C. To avoid overloading the compressor motor, self-check the overload protection device before compressor operation. When the compressor overload protection is in effect, it must not be forced to turn on. The cause must be found and the compressor can be turned on after elimination. However, it is our negligence After this point, the system was forced to start, and after the fluorine oil separator was repaired and replaced, the refrigeration system needed to be evacuated. The repairer vacuumed the refrigeration system for a long time, and the copper pipes in the intercooler The welds of the water system are interconnected, causing the water in the water system to enter the refrigeration system when it is stopped, causing the three mixtures of lubricating oil, refrigerant and freon to leak out at the angle valve of the intercooler, and finally in a helpless situation Next, we invite the manufacturer’s service engineer to replace the refrigeration compressor and intercooler, and replace the similar semi-hermetic refrigeration compressor, brand: Bitzer, model: 4HE-18Y-40P, crankshaft lubricating oil heating power is 220-140W , And finally the machine worked normally.

From this incident, we learned the following lessons. When the structure of the refrigeration compressor is not clear, it is not advisable to rush to replace some main components without communicating with the manufacturer, such as some abnormal equipment failures. Phenomenon, it is best to negotiate with the equipment manufacturer or ask the equipment manufacturer to diagnose on site before proceeding with maintenance.