Proper calibration of pressure relief valves ensures they operate at the correct set pressure within tolerance.
Standards
ISO 4126 and ASME PTC 25.3 set the tolerance bands and the test conditions; API 527 governs the seat-tightness acceptance criteria that go with them.
Calibration Frequency
Frequency follows service severity: clean, non-fouling duty can run to five years, while fouling or corrosive duty is often annual.
Common Mistakes
Testing with the wrong medium, ignoring backpressure correction, and failing to record the as-found set pressure before adjustment are the three that most often invalidate a certificate.
Contact our calibration team for a certified test.