IQ / OQ vs PQ
The three qualification stages — installed right, operates right, performs right.
What a comparison is not
A comparison is SPEQ’s reading of how two published documents differ. Neither is the right answer, it is not a determination of which applies to you, and neither is summarised in a way that replaces reading it.
Qualification proves a facility, utility, or piece of equipment is fit for use, in staged steps. Installation Qualification (IQ) confirms it is installed correctly to specification; Operational Qualification (OQ) confirms it operates as intended across its range; Performance Qualification (PQ) confirms it performs consistently under real production conditions. IQ and OQ are essentially verification; PQ is where qualification meets validation.
| ASPECT | IQ / OQ | PQ |
|---|---|---|
| Question | IQ: installed per spec? · OQ: operates across its range? | PQ: performs consistently in actual use? |
| Conditions | Static (IQ) / functional testing across operating limits (OQ) | Representative, real (or simulated-real) production conditions |
| What is checked | Correct components, utilities, calibration; functions and alarms | Sustained, reproducible performance producing conforming output |
| Nature | Verification against design/functional specs | Validation — demonstrating consistent intended performance |
| Sequence | IQ before OQ; both before PQ | After IQ/OQ pass; often multiple runs |
| Governing references | EU GMP Annex 15; ASTM E2500 risk-based C&Q | Annex 15 PQ; process validation Stage 2/3 |
You are doing IQ/OQ when you confirm equipment is correctly installed and operates as specified — the verification steps that must pass before any performance claim.
You are doing PQ when you demonstrate, under representative production conditions and usually over multiple runs, that the equipment/process reliably delivers conforming output — the validation step.
Installed right (IQ), operates right (OQ), performs right (PQ). The order is not optional: PQ evidence is meaningless if IQ/OQ never confirmed the basics. Modern risk-based commissioning and qualification (ASTM E2500, Annex 15) lets you scale the effort to risk and leverage vendor/commissioning data — but the logical progression from installation to sustained performance still holds.
IQ / OQ vs PQ: frequently asked questions
Common questions on how IQ / OQ and PQ differ and when each applies.
What is the difference between OQ and PQ?
OQ confirms the equipment operates as intended across its specified operating range (often using test conditions and worst cases). PQ confirms it performs consistently under actual production conditions with real (or representative) materials and loads. OQ is capability; PQ is sustained real-world performance.
Is IQ/OQ/PQ the same as process validation?
They overlap but are not identical. Equipment qualification (IQ/OQ/PQ) qualifies the equipment/utilities; process validation demonstrates the manufacturing process reliably makes conforming product. PQ of equipment feeds into the broader process-validation lifecycle (Stages 1–3).
Do I always need all three?
You need qualification proportionate to risk. Under ASTM E2500 and Annex 15, risk-based approaches let you leverage commissioning and vendor documentation and focus formal qualification on quality-critical aspects — but the IQ→OQ→PQ logic (installed, operates, performs) still structures the evidence.
Where does DQ (Design Qualification) fit?
DQ precedes IQ: it verifies the proposed design meets the user/functional requirements before you build or buy. Annex 15 recognises DQ as the documented verification that the design is suitable for its intended purpose.