Safety Relief Valve / Pressure Relief Valve
See All Frequently Asked Questions
What is a Safety Relief Valve?
A Safety Relief Valve is a pressure-protection device that protects your compressed air system from dangerous overpressure by automatically releasing pressure before it exceeds the equipment’s safe operating limit.
What could TSSA look for during an inspection?
Overpressure protection is an important part of pressure equipment safety. A missing, inoperable or incorrectly set safety relief device can be considered a high-risk violation.
How can I tell when a Safety Relief Valve (SRV) was installed?
Most Safety Relief Valves (SRVs) have a tag or nameplate showing the manufacturer, pressure rating, and often the installation, certification, or recalibration date. Checking this tag can help determine whether the valve is approaching the TSSA-required five-year recalibration or replacement interval. If the tag is missing or unreadable, maintenance records should be reviewed to verify the valve's age.
How often must a safety relief valve be tested in Ontario?
Ontario requirements mandate that a safety relief valve's operation be manually tested and documented annually.
What is MAWP on an air receiver tank?
M.A.W.P. (Maximum Allowable Working Pressure) is the highest pressure an air receiver tank or pressure vessel is designed to safely contain under normal operating conditions. This rating is set by the manufacturer and is listed on the tank nameplate. When selecting tank accessories, the Safety Relief Valve (SRV) should be set below the tank's MAWP. Knowing your tank's MAWP is essential for safe operation, proper component selection, and pressure vessel compliance.
How often must a safety relief valve be replaced?
According to TSSA requirements, safety relief valves must be recalibrated or replaced every five years. However, valve age, condition, service history, and annual test results should also be considered. If the valve’s history is unknown or its reliability cannot be verified, replacement may be the safest and most cost-effective option.
What happens if a safety relief valve is not replaced after five years?
Operating beyond the required service interval may create compliance concerns and increase operational risk. Facilities should maintain records and replacement schedules to ensure ongoing conformity with applicable regulations.
Does every compressed air receiver tank require a safety relief valve?
Yes. Air receiver tanks and pressure vessels require properly sized pressure-relief protection as part of safe compressed air system operation.
Do we need records of inspections, testing and replacements?
Yes. Good documentation provides a clear history of the valve and helps demonstrate that your pressure equipment is being properly maintained.
Can a safety relief valve be recalibrated instead of replaced?
Yes. TSSA requirements allow for either recalibration or replacement every five years, provided the valve remains compliant with applicable standards.
Are Safety Relief Valves Expensive?
Cost is relative to the size of the relief valve. They range from <$50 for a small ¼” ported valve, to as much as $1,500 for a very large valve. The true risk of cost is two-fold. 1) The inherent safety of your staff and equipment, and 2) The cost incurred, should a TSSA inspector shut your compressed air system down until the non conformance is rectified.
My compressor is serviced regularly. Does that mean my relief valves are being tested?
Not necessarily. Routine compressor servicing does not automatically mean your safety relief valves have been inspected or tested. Ask your service provider—and make sure it’s documented.
Can a relief valve look fine but still fail?
Yes. Corrosion, contamination, mechanical wear or simply years without operation can prevent a valve from opening correctly when it is actually needed.
What happens if the valve is set at the wrong pressure?
A relief valve must protect the equipment within its allowable pressure limits. An incorrectly selected or set valve can leave your pressure vessel inadequately protected.
Could a failed relief valve result in equipment being shut down?
Potentially, yes. A serious safety violation may require affected equipment to be taken out of service until the issue has been corrected.
Our air receiver is exempt from periodic inspection. Can we ignore the relief valve?
No. An exemption from periodic inspection does not mean safety devices should be ignored. Pressure equipment still needs to be maintained in safe operating condition.
Who is responsible for making sure the relief valves are compliant?
Ultimately, the owner/operator of the pressure equipment needs to ensure that the equipment and its safety devices are properly maintained.