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Pressure-Relief Valve Maintenance
Vital to any industrial or large commercial refrigeration system are pressure (safety) relief valves. These valves provide emergency relief from over-pressure in refrigeration systems. The ANSI/ASHRAE 15-1994 Safety Code for Mechanical Refrigeration requires pressure vessels of all refrigeration systems to be protected by a pressure relief device. For most pressure vessels, dual relief valves connected via a 3-way shut-off valve are required. It is essential that routine inspection and maintenance occurs on these important valves. In time of emergency, can you be sure your pressure relief valve will operate properly?

Industry-Accepted Tips

• Atmospheric discharge lines should have adequate rain and moisture protection, and be capable of draining condensate and rainwater.
• Check to make sure the relief valve exit stays unobstructed.
• Routine maintenance of pressure relief valves should include visual inspection of the relief valve and discharge piping every six months.
• Relief valves should be replaced at intervals of no longer than five years of service.
• Maintain pressure relief valve data in an inventory record, including location, size, set pressure, manufacturer, capacity, date installed, dates of inspections, and latest date for replacement.
• Pressure relief valves should not be discharged during installation or start-up.
• Replace pressure relief valves once they have discharged.

Hansen valves come with highly-durable, plastic date tags to help quickly and easily identify when a pressure relief valve was installed. In addition, Hansen recommends the following.

Hansen’s Additional Tips

• Never expose your face or body to a connected relief valve exit.
• Avoid trapped ice build up between valves and other equipment.
• Reduce inlet pressure to zero before attempting to install or replace any pressure relief valve. Preferably, and as required by most codes, use a three-way dual shut-off valve to isolate relief valves for individual inspection or replacement.
• Check the nameplate or installation date tag to be sure the time-in-service does not exceed five years.

Look for corrosion and leaks. If there is any doubt about the internal condition of a relief valve, remove and inspect it internally. If there is any question about a valve’s condition, replace it.