Glossary
ASME PTC 9 (compressor performance testing)
ASME PTC 9 is the Performance Test Code published by the American Society of Mechanical Engineers for displacement (positive-displacement) compressors. It defines the test method, instrumentation accuracy, allowable uncertainty, and report content for verifying flow, power, and efficiency. Together with PTC 10 (dynamic compressors) it underpins acceptance testing in industrial and utility contracts.
What it is
A PTC 9 test fixes the inlet conditions (or corrects for them), measures flow with a calibrated orifice or other approved primary element, measures shaft or electrical input power, and accounts for departures from design conditions. Allowable test uncertainty is calculated and disclosed alongside the results. Where ISO 1217 covers the equivalent test internationally, PTC 9 is the U.S. reference for acceptance.
Why it matters
Procurement contracts for industrial compressors often include a PTC 9 acceptance test as a contractual deliverable. If the as-tested SCFM falls short of guaranteed SCFM by more than the allowable uncertainty, financial remedies (liquidated damages, replacement of components) kick in. Without a PTC 9 reference, “performance shortfall” is open to interpretation; with PTC 9, it is contractually enforceable.
How it is used in our catalog
CAGI data sheets linked from our catalog reference PNEUROP / CAGI / ISO 1217, which aligns closely with PTC 9 methodology. For large procurements involving a contractual performance test, the installer directory covers commissioning agents experienced in PTC 9 witness testing.
Common questions
Is PTC 9 the same as a CAGI data sheet?
No. A CAGI sheet is a manufacturer’s published performance under a defined factory test. PTC 9 is a field acceptance procedure run on the installed machine. They use compatible methodology, but the CAGI sheet is the data sheet and PTC 9 is the verification protocol.
Does PTC 9 cover centrifugal compressors?
No. Dynamic compressors fall under ASME PTC 10. PTC 9 is specific to positive-displacement designs (reciprocating, rotary screw, rotary vane, rotary lobe).
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