Pollution blowing and air tightness test of refrigerating system in purification workshop
Pollution blowing and air tightness test of refrigerating system in purification pharmaceutical cleanroom
After the refrigeration system is installed, there will inevitably be welding slag, rust, oxide scale and other impurities left in the system. If it is not cleaned up, the valve core will be damaged when the refrigeration device is running. After the filter, it will be damaged. The filter is clogged, for this reason in the refrigeration unit...
Text label: Refrigeration system of purification plant, blowing and air tightness test
Fouling and air tightness test of the refrigerating system of the purification plant
After the refrigeration system is installed, there will inevitably be welding slag, rust, oxide scale and other impurities left in the system. If it is not cleaned up, the valve core will be damaged when the refrigeration device is running. After the filter, it will be damaged. To block the filter, for this reason, the system must be carefully blown before the trial operation of the refrigeration unit. Generally, compressed air or nitrogen of 0.5-0.6MPa is used for the blowing; in the case of no compressed air or nitrogen, a refrigeration compressor can also be used instead. , but pay attention to the exhaust temperature of the refrigeration compressor when using it, which does not exceed 125 °C, otherwise the viscosity of the lubricating oil will be reduced and the moving parts of the compressor will be damaged. In the low-pressure system, the sewage outlet should be selected at the lower part; in addition, when the refrigeration system is overhauled, it is also necessary to use compressed air to blow off the remaining oil and impurities in the system.
The air tightness test is carried out after each single piece of the main components of the refrigeration device has undergone the pressure test and the system blowing work is completed. It is an extremely important link to check the quality of installation and repair; the air tightness of the refrigeration device The performance test includes three procedures: pressure leak test, vacuum leak test and refrigerant leak test. The pressure test is to fill the entire refrigeration system with nitrogen or air under a certain pressure, so that the inner wall of the pipe wall equipment is pressurized to check whether there is leakage in the joints, flanges, pipes, and equipment after installation; industrial nitrogen is mostly used in the pressure test. Nitrogen has the advantages of no corrosion, no moisture, low price, and easy operation. Compressed air is not used as much as possible because it contains moisture and impurities. Before filling nitrogen, a pressure gauge should be connected to the high and low pressure pipeline. When the nitrogen bottle is full, the pressure is 14.7MPa. Close all the valves open to the atmosphere, the suction and exhaust shut-off valves of the compressor, the oil return valve of the oil separator, open the bypass valve of the expansion valve and all other valves at the pipeline port; open the valve of the nitrogen bottle, and charge nitrogen into the system, In order to save the air source, a step-by-step method of pressurization can be used, first rise to 0.3-0.5MPa, check for large leaks, and then pressurize to the test pressure value of the low-pressure system after the leaks are discharged, such as R12 refrigerant pressurization to 0.98MPa. Zhongjing Global Purification can provide consulting, planning, design, construction, installation, transformation and other supporting services for purification workshops and clean workshops.
For the pressure test of the ammonia system after the overhaul, it should be noted that ammonia should not be left in the system; the leak detection work should be careful and careful, the soapy water used for leak detection should have a certain concentration, and it should not be too thin, otherwise it should be applied to the inspection The time spent at the place is too short, and it is difficult to find the leak; when using a brush or a small brush to apply soapy water to the joints and welds, carefully check each place. Leakage; in addition, the method of listening to the sound can also be used to check for leakage. Where there is leakage, there will be some faint noises; all leakage points identified during the inspection should be marked, and the leak repair work will be carried out after all inspections are completed. , The leak repair work should not be carried out in the stamping state, because it is not safe, the nitrogen should be released before the leak repair work, and the stamping test should be performed again after the leak repair work is completed until the whole system does not leak. During the pressure test, the system should bear the specified pressure of 24H, the pressure drop of the first 6H should not exceed 2%, and the remaining 18H should be able to keep the pressure stable; during the pressure test, the influence of the environmental temperature change on the system pressure value should be considered. The pressure drop caused by the drop in ambient temperature cannot be mistaken for a leak. After the pressure leak test is completed, the vacuum leak test is carried out. There are two purposes of the vacuum leak test. One is to check the tightness of the system under vacuum conditions, and the other is to remove the residual gas and moisture in the system.
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