Question: Do both relief valves on a dual assembly have to be replaced every five (5) years, or just the relief valve that has been subject to system pressure? Answer: Most pressure vessels in an ammonia refrigeration system exceed 10 cubic feet in volume (normal exceptions are oil pots and small oil separators), and therefore are […]
Question: If two independent ammonia refrigeration systems share a water diffusion tank should they be considered one (1) or two (2) processes under RMP and PSM? Answer: This is a great question that addresses the issue of “co-location“. In order to correctly answer this question, we must first consider the definition of a Process. Title 40 §68.3 Process means […]
Since 1994, ammonia refrigeration systems subject to the requirements of the Uniform Mechanical Code or California Mechanical Code have been required to install an Ammonia Diffusion Tank for the purpose of relief valve termination. Originally, the codes required the following: 1994 UMC §1119 Ammonia Discharge Ammonia systems shall be provided with an emergency discharge into a tank of water provided exclusively for […]
Question: Can a single relief valve assembly be used to protect more than one ammonia refrigeration pressure vessel? Answer: While it is definitely not common-place, it is compliant to utilize one relief assembly to protect multiple pressure vessels, provided that the relief valves are sized correctly and the vessels are interconnected without allowance for independent isolation. […]
Question: Can a stop valve be installed before or after a relief valve? Answer: If your initial reaction to this question is “NO“, then you are in good company. Most refrigeration experts (and people with common sense) can see the danger in installing stop valves before/after pressure relief valves….However, as is the case with many issues, there […]
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