Recent Blog Posts

Manufacturer Instructions and Ammonia Three-Way Relief Isolation Valves

May 29th, 2018

It is common practice in the ammonia refrigeration industry to install a three-way isolation valve upstream of relief valves protecting an ammonia refrigeration pressure vessel. For vessels larger than 10 ft3, this is required by most model codes and standards. These three-way valves allow a relief valve to be replaced without the hassle of pumping […]

Comparing RAGAGEPs: Relief Valve Sizing

May 15th, 2018

It widely known that pressure vessels must be equipped with over-pressure protection (2015 ASME B&PVC UG-125), often in the form of a pressure relief valve. Properly sizing a relief valve requires engineering analysis which accounts for the type of over-pressure scenarios that might occur. In most cases, model codes and standards (RAGAGEPs) specify the relief […]

Pipe Wall Thickness

November 14th, 2017

Pipes are one of the areas of an ammonia refrigeration system most vulnerable to leak. Systems often have hundreds, or even thousands of feet of ammonia pipes serving a variety of purposes. Historically, IIAR Bulletin No. 110 has been the RAGAGEP which governs ammonia pipe inspections and maintenance. ยง6.7.1 requires that: All uninsulated piping and […]

Update on Ammonia Diffusion Tanks

September 5th, 2017

Since 1994, jurisdictions which adopted the Uniform Mechanical Code (UMC) have required ammonia refrigeration systems to be equipped with a diffusion tank to which all pressure relief valve discharge pipes must terminate. As a state, California has adhered to the California Mechanical Code (CMC) which is a derivative of the UMC. The most recent version […]

Relief Valve Piping System Design Scenario

January 24th, 2017

One often overlooked aspect of a relief valve discharge termination piping system is the scenario that was used at the basis of the piping design. Most designers understand that termination piping must be sized so as to not cause excessive back pressure in the manifold when a relief valve lifts. The question, however, that must […]