Shanghai Sairui Electrical Maintenance Co., Ltd.

&Shanghai Sanyo Ultra-low Temperature Refrigerator After-sales Service Center: Hourly After-sales Service Telephone:
Application fields of Sanyo Ultra-low Temperature Refrigerator: scientific research institutes, medical and health care, military aviation, biopharmaceuticals, university electronics, vacuum coating, metal processing, electronic chemical industry, oceangoing fishery and other industries. The company's products have been exported to all parts of the country and countries and regions such as Singapore, Malaysia, Turkey, North Korea, etc., and have gradually won recognition from domestic and international markets with their strong cost-effectiveness advantages. At the same time, we design and produce other non-standard ultra-low temperature equipment according to customer needs. Today, as the market economy takes off, we will make outstanding contributions to the prosperity of the ultra-low temperature application industry of the Chinese nation with our unremitting hard work and pioneering spirit!
Overview
The ultra-low temperature freezer produced by the British R Company has the characteristics of It has the characteristics of large volume, low freezing temperature, and the lowest temperature can reach ℃. It is mainly used for medical research and storage of medical biological products. In the absence of drawings and maintenance data, through careful analysis, calculations and maintenance practices, some experience and understanding of repairing this type of freezer can be gained.
The ultra-low temperature freezer refrigeration system is composed of independent single-stage refrigeration systems with different refrigerants, which are connected through evaporative condensers to form an overlay refrigeration system. The evaporative condenser is both a high-temperature evaporator and a low-temperature condenser. During operation, the heat absorbed by the low-temperature evaporator returns to the low-temperature compressor. The evaporative condenser performs heat exchange and transports the low-temperature heat to the high-temperature stage. , together with the high-temperature stage compression heat, enter the high-temperature stage condenser, and the heat is discharged into the external environment through the condenser.
Fault 1
The high-temperature compressor starts normally, but the low-temperature compressor cannot start, and the temperature in the refrigerator does not meet the requirements.
Troubleshooting and maintenance. The low-temperature stage cannot be started. After eliminating the fault in the control circuit, we measured the terminals of the low-temperature stage compressor and found that the running winding resistance was infinite, indicating that the compressor was burned out. The technical parameters cannot be seen on the compressor, and there is no information to check. Moreover, it is considered to use low-temperature refrigerant R. There is no compressor of the same model in China that can be directly replaced. Based on the analysis, calculation and market investigation of multiple parameters such as the box insulation efficiency, box volume, compressor power and the temperature required by the refrigerator, it was determined that the compressor produced by the American Taikang Company met the technical parameter requirements of the machine, and it was decided to use it to replace the low temperature stage compressor. I purchased R refrigerant and after pressure, leak detection, and vacuuming, in order to prevent liquid shock, a long capillary tube was used as a liquid filling tube when the machine was shut down, and R was injected every time, and then stopped for a period of time before injecting again. When the low-temperature suction pressure reaches about 100°C, gradually set the freezer temperature downward from ℃. After a period of observation, the lowest temperature of the freezer can reach ℃.
Fault 2
The high-temperature stage can start normally and works basically normally. Although the low-temperature stage can also start, the low-temperature stage compressor is very noisy and cannot cool the inside of the box.
Troubleshooting and maintenance. After careful observation, it was determined to be general mechanical noise. The reason may be a lack of refrigeration oil, which reduces the air-tightness of the compressor, resulting in low compressor efficiency and no cooling. Since there is no original data, the amount of refrigeration oil injected cannot be known. Remove the low-temperature compressor, first slowly inject Sun brand refrigeration oil into the compressor, and then restore the compressor. It is found that the noise is significantly reduced. Remove the compressor for the second time and then add refrigeration oil to restore the compressor refrigeration system. Repeat a small amount of Refill several times until the compressor noise disappears and operation is normal. Add R refrigerant to the low-temperature level according to the conventional process. After a period of observation, the freezer resumed its working performance indicators.
Some experiences
In the absence of original equipment data, in order to repair a large imported ultra-low temperature freezer, it is necessary to find some similar freezer data of different models for reference in order to draw empirical intermediate conclusions for the benefit of Analysis and judgment of faults, selection of substitutes and repair processing.
Be careful when repairing, don't be afraid of troubles, and don't rush for success. For example, when adding refrigeration oil, you need to repeat it in small amounts many times until it is suitable.
For the substitution of imported spare parts, we must carefully weigh the relationship between various parameters, carefully calculate, fully demonstrate, and strive to improve the pertinence of the selection of substitutes, otherwise it will be difficult to achieve the expected results
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