With commissioning successfully completed and an IQ Report approved, OQ is performed to verify that the specified operating range is achievable, in (simulated) realistic ‘worst case’ conditions.  For example, a tank would be verified as capable of being heated up at the specified rate, on the coldest day of the year, while a maximum supply is demanded of the steam heating medium by the HVAC (Heating, Ventilation, Air Conditioning) system, and two autoclaves and a freeze dryer are entering their steam sterilisation cycles.

We strongly recommend that OQ be limited to the parameters impacting on product quality, and that, on successful completion, they are trended to enable early awareness of any drift towards the upper or lower acceptable limits permitted by SOPs.  To preclude the need for requalification, any subsequent interventions, such as planned preventive maintenance, should include all the functional testing, performed during commissioning, System Acceptance Testing (SAT) or OQ, necessary to demonstrate control of these parameters has been reinstated.