IQ, OQ, and PQ for Temperature-Controlled Equipment

A new -80°C freezer gets delivered on Monday. By Wednesday, it has been pulled down to temperature, and someone wants to start loading samples. Before that happens, most regulated sites want three documents signed: an Installation Qualification, an Operational Qualification, and a Performance Qualification. 

Each one tests something different. When a qualification package falls apart in an audit, it is usually because someone treated one of those documents as if it covered the other two. 

This post walks through what each stage checks on a refrigerator, freezer, incubator, or other controlled temperature unit (CTU), and where sites tend to cut corners. It applies to pharmaceutical, biotech, hospital, and blood and tissue bank equipment alike. 

Why there are three stages 

A freezer can go wrong in three broad ways. It can be installed wrong. For example, it could be plugged into a circuit that is not on the generator or pushed against a wall with no room for the condenser to breathe. It can be installed correctly and still control badly or it can hold temperature fine while empty and drift once it is packed with racks and opened forty times a day. 

IQ looks for the first problem, OQ for the second, and PQ for the third.  

Installation Qualification (IQ) 

The IQ is a records check and an equipment walkdown. You are confirming that what showed up matches what was ordered and that it was set up the way the manufacturer, and your own requirements, say it should be. 

On a typical CTU, the IQ covers: 

• Make, model, and serial number against the purchase order and user requirements
• Electrical supply, including voltage and emergency power if it was specified
• Clearance and ventilation around the unit
• Shelving, racks, and accessories
• Calibration status of the controller and any built-in sensors
• Manuals, drawings, and certificates on file 

 A passing IQ tells you the equipment is the right equipment and was set up correctly. It says nothing yet about whether it holds temperature. 

Operational Qualification (OQ) 

The OQ is where the units initial testing happens. Most OQ work is done with the chamber empty, so the results describe the equipment itself instead of the equipment plus whatever happens to be inside it. 

Common OQ tests for a CTU: 

• Setpoint control and stability over a defined period
• High, low, and door alarms
• Empty chamber temperature mapping to find the warm and cold spots
• Recovery time after a door opening
• Behavior during and after a power interruption 

 A passing OQ shows the unit can hold its range. What happens in daily use is a separate question, which we covered in Empty vs Loaded Chamber Mapping: Why Both Studies Matter. 

Performance Qualification (PQ) 

PQ tests the unit the way it will be used: loaded with product or a representative load. 

For a CTU, a PQ usually includes: 

• Loaded chamber mapping with a load pattern that mimics a maximum load 

 A passing PQ show that the unit can hold its range when storing actual product. If the site later adds a shelf, increases the maximum load, or starts storing something with a tighter range, the current PQ may no longer represent how the unit is being used and additional testing may be required.  

Requalification 

Equipment may need partial or full requalification after: 

• Relocation
• Repair or replacement of a major part, such as a compressor or controller
• Firmware or software updates
• Shelving or configuration changes
• A change in the load or in what is stored
• Temperature problems nobody can explain
• A periodic review date set by your SOPs or risk assessment 

 How much to repeat depends on the change. A firmware update might mean redoing parts of IQ and OQ. A new load pattern might only need a new PQ. Whatever you decide, run it through change control and write down the reasoning, so the next auditor sees a decision instead of a gap. 

Documentation 

Each stage needs an approved protocol before testing starts and a report afterward. Someone pulling the file three years later, often during an audit, should be able to find: 

• What was tested and the acceptance criteria
• Evidence the criteria were approved before testing began
• Calibration records for the test instruments
• The results and whether they passed
• How deviations were handled
• Who reviewed and approved each stage 

A package with signatures on every page but no pre-approved acceptance criteria is one of the easier findings an auditor can write up. 

Qualification services from Rees Scientific 

Rees Scientific supports IQ, OQ, and PQ for refrigerators, freezers, CTUs, incubators, and other controlled environments, from protocol writing through execution and the final report. Testing uses calibrated, traceable instruments, and temperature mapping is run both empty and loaded. See our validation and calibration pages for details. 

Rees also provides EMS validation, so the monitoring system watching the equipment can be qualified alongside it. 

Frequently asked questions 

What do IQ, OQ, and PQ stand for? 

Installation Qualification, Operational Qualification, and Performance Qualification. IQ checks the installation, OQ checks that the equipment operates within its range, and PQ checks that it performs under real use. 

What is the difference between OQ and PQ? 

OQ tests the equipment across its operating range, usually with the chamber empty. PQ tests it under actual or simulated use, including a realistic load and normal door openings. 

Can IQ, OQ, and PQ be combined into one protocol? 

It is common to combine all testing into a single IOPQ document.  

Does qualification expire? 

Qualification describes the equipment and configuration that were tested. Relocation, repairs, software updates, or new load patterns can make it out of date. Many sites also requalify on a schedule based on risk. 

Talk to Rees about qualification 

If you are qualifying new equipment, or are not sure an existing package would hold up in an audit, Rees can help plan and run the work. 

Schedule a qualification consultation with Rees Scientific.