Recent Blog Posts

Q&A | Co-Location

February 24th, 2015

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 […]

Mechanical Integrity 101 | Ammonia Diffusion Tanks

February 2nd, 2015

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 […]

Q&A | Relief Valves Protecting Multiple Vessels

December 9th, 2014

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. […]

Q&A | Stop Valves on Relief Valves

November 11th, 2014

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 […]

Q&A | Compressor Relief Valves

October 14th, 2014

Question: What is the proper procedure for selecting the pressure relief valve capacity for a positive displacement compressor? Answer: ANSI/IIAR 2-2008 Addendum B §6.1.2.1 addresses this very question. Furthermore, Appendix E (Informative) of that same document gives a detailed example of one acceptable method for determining the proper capacity. A summary of the steps in Appendix […]