After installing a new refrigeration system at your facility, there is a critical step between you and a successful startup: the pressure test. It’s not just a box to check – it’s your frontline defense against dangerous leaks, environmental impacts, and costly production delays. While different methods of pressure testing exist, the primary refrigerant side of industrial systems use pneumatic pressure testing with very dry air or nitrogen to avoid moisture contamination. Whether you’re a seasoned professional or managing your first installation, these safety tips can help you protect your team, your facility, and your bottom line.
Prepare Your Space
Before beginning any testing, develop a game plan. Identify which system portions will be tested and be sure it’s totally isolated from existing portions that may be in service. It’s not recommended to pressure test against “live” system valves containing refrigerant on the other side. This could cause contamination if a valve leaks. Make sure there’s a clear procedure in place that outlines the type of gas used, pressure, duration, schedule, and other key success criteria of the test.
It’s also important to valve off and isolate any sensitive instruments or components not rated for the test pressures. This includes equipment tested by the manufacturers – never expose equipment to pressures above their rating. Be sure all valves and control devices that don’t lead to atmosphere are open in the system being tested. Use a regulator to control the testing medium supply pressure and a relief device rated for the full regulator capacity. The relief device should have a lifting pressure at least 25 pounds per square inch gauge (PSIG) above the test pressure.
Prepare Your People
When your system is properly prepared, make sure all onsite personnel are aware of the test. This helps to avoid any surprises and makes sure everyone knows what’s going on. Only trained and qualified contractors and operators should administer the test. Anyone involved with testing should be wearing personal protective equipment including safety goggles, gloves, and protective clothing to minimize risk of injury.
Additionally, make sure a safety perimeter is set up, and anyone not directly involved with the test stays a safe distance away from the perimeter. If system design permits, it’s often beneficial to split up large pressure test volumes into smaller zones to help limit the size of the safety perimeter and amount of compressed gas.
Go Slow
Usually, the test starts with a low-pressure test of 25 PSIG to find any major leaks before slowly raising the pressure in stages. Stop between stages and keep an eye out for any leaks. After the initial leak check it’s common to first go to 50% of the test pressure and stop at 10% intervals. The pressure test should, at least, rise to 110% of the design pressure for 10 minutes; but don’t exceed 130% of the design pressure of any system component.
It’s important to have a written procedure ahead of time so qualified professionals can follow these best practices. If you spot any leaks, fix them right away before continuing, but be sure to first release the pressure. This step-by-step approach reduces the chance of accidents. Once the test runs successfully, bleed the system down to design pressure and check for leaks. Be careful when venting the test gas, particularly with nitrogen, due to risks of asphyxiation. Finally, direct test gas discharge to designated outdoor venting locations, maintaining a safe distance from all air intakes.
Conclusion
Safety during pressure testing is key to avoiding accidents and ensuring system reliability. These are just some of the tips and guidelines you can use to help conduct pressure tests in a more safe and effective manner. Always put safety first, abide by all code requirements, and stick to the procedures put in place to protect both people and equipment.
