A Proven Solution to Refrigerant Relief Valve Monitoring and Reporting

A Proven Solution to Refrigerant Relief Valve Monitoring and Reporting

Refrigeration systems are pressurized mechanical systems that can have a hazardous Group 2 refrigerant, such as anhydrous ammonia, contained inside. These systems require an overpressure protection device. When a release of refrigerant occurs, the event is strictly regulated. As noted previously on this blog, anhydrous ammonia is regulated by the Occupational Health and Safety Administration (OSHA) and the U.S. Environmental Protection Agency (EPA), as well as some state programs. In any event, the timing, duration, and refrigerant loss must be recorded promptly.

Typical installations present challenges

By code requirement, dual relief valve assemblies are installed on larger pressure vessels so that in the case of a release a quick recovery can be accomplished, also to prevent the loss of all of the refrigerant should a single relief valve not reseat. The discharge from all relief valves are commonly piped into a single collection header and either vented outside of a building or piped into a dispersion tank filled with water. In either case, a common header is used to route the release away from occupied space.

However, with the use of a common collection header for relief valve discharges, it becomes virtually impossible to identify the location of a vessel experiencing an over-pressure condition and release because the refrigerant quickly fills the header. If the over-pressure condition has subsided and the relief valve reseated, it is generally considered frustrating and virtually impossible to pinpoint the location and cause of the release.

Refrigerant Relief Valve Monitoring and Reporting System© (RRVMR)


Barrow Systems, Inc. has developed a stand-alone system (patent pending) that monitors refrigerant pressure vessels and all relief valve discharge piping for both indications of an impending high-pressure condition and any relief valve discharge event. An alarm indicates abnormal pressure conditions prior to a high-pressure release, which can alert personnel to remedy the situation.

If a release does occur, the RRVMR’s sensors detect a release condition in the relief valve discharge piping immediately downstream of the reacting valve and provide a conditioned signal to the system processor that an overpressure condition has occurred. The system will continue to monitor the release through its duration when either the relief valve reseats or the 3-way valve is adjusted to select the parallel valve.

Accurate data before, during, and following a discharge event

During a release event, the RRVMR’s system processor can determine the location and duration of the discharge and calculate, with pinpoint accuracy, the loss of refrigerant in pounds. At the conclusion, the system controller will displays and can send a message to a printer containing the event start time and date, end time and date, duration of the event, and loss of refrigerant. The system has an optional feature that can also initiate an automatic purge of the relief valve discharge header with a timed purge of high-pressure air. The monitoring and reporting system has Ethernet capabilities that enable interface with plant systems, and it can be equipped with a battery backup device.

Woodard & Curran is working with Barrow Systems, Inc. to install the Refrigerant Relief Valve Monitoring and Reporting System© at beverage production facilities. These systems save time and money, especially when the system alerts maintenance ahead of a release event. It is an easy-to-use system that employs a human machine interface video display to show, in real time, the precise details of a pressure vessel approaching its relief pressure, exceeding its relief pressure and the details of the release, or indicate all vessels are within their normal pressure range.


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Industrial Utilities

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