How to perform gas displacement when working on an ammonia refrigeration system?
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Ammonia is a toxic and explosive hazardous gas. In ammonia refrigeration systems, what precautions should be taken if there are leaks in the equipment or pipelines and welding work is required? How should purging be carried out?
The replacement should be thorough, ensuring no dead corners remain; using water for replacement is the safest approach. Of course, the main criterion is that the sample analysis results after replacement should be satisfactory
It can also be replaced with nitrogen; blind flanges must be installed at the corresponding connection points, and the frequency of analysis during heating operations should be increased.
Drain the liquid ammonia from the equipment pipes. Displace with nitrogen. Effectively isolated from other devices (blind flange). Flame test analysis is satisfactory.
For ammonia systems, unless it is absolutely necessary, it is best not to use water for cleaning or flushing. Given the severe hazards posed by water in ammonia systems, our factory uses nitrogen to purge such systems; for larger systems, purging is carried out in stages. This method yields a higher rate of successful analysis (although it takes longer), yet it remains relatively faster compared to water cleaning.
After hearing everyone’s opinions, I think using nitrogen for replacement is the safest option. However, I noticed that our ammonia system seems to use air rather than nitrogen; this isn’t very safe, but is it really a problem?