Uponor recommends conditioning the system at 1.5 times the test pressure, or 120 psi. The following conditioning procedure is unique to PEX-a due to the high degree of crosslinking and associated thermal and elastic properties of the pipe.
When pressure is applied against the inner wall of PEX-a, the internal diameter (ID) of the pipe will slightly increase, causing the pressure to drop while the system equalizes. After a period of 30 minutes, the PEX-a piping will be sufficiently conditioned to start the pressure test.
Conditioning and Sustained Pressure Testing Procedure
1. Visually confirm all connections are properly made per Uponor’s installation guidelines.
2. Ensure that all components, fixtures and equipment not rated for the test pressure are isolated from the test system.
3. Ensure that all other thermoplastic piping materials are isolated from the test system.
4. Fill the system with potable water, air or a mixture of both.
5. Condition the system at 1.5 times the required test pressure for 30 minutes. This will require constant pumping or cycling the valve and compressor to maintain a pressure of 1.5 times the test pressure. If cycling the valve and compressor, apply additional pressure once the psi has dropped 10 lbs.
6. After conditioning the system for 30 minutes, quickly relieve excess pressure by opening the valve. Close the valve when the system has reached the desired test pressure. Note: Uponor recommends a test pressure of 80 psi (unless local code dicates higher pressures).
7. Once the valve is closed, confirm a slight rise in pressure (3 to 6 psi). This will occur since the pipe’s internal diameter (ID) is shrinking from its conditioned state to equalize at the lower pressure.
8. Visually check for leakage and monitor the pressure for the duration specified by local code. (A typical pressure test can range from 2 to 24 hours.)
9. If there is no reduction in pressure, the system is regarded as leak tight. Note: Slight fluctuations of pressure are normal due to ambient temperature changes, especially during long durations (e.g., 24 hours).
10. Flush the system as required by code.