SOP: Refrigerator Operation and Calibration

In short: This illustrative SOP template describes operation, temperature monitoring and calibration for a quality-control refrigerator or freezer. It is not an approved site procedure: QA must set limits and actions for the unit and the materials stored in it.

Objective

To provide a template for operating and maintaining a quality-control refrigerator or freezer and for documenting its temperature and calibration status.

Scope

Adapt this template for the specific unit, stored materials, product or material specifications, and the site’s quality system. Use the storage conditions stated in the approved product or material specification. WHO lists several possible temperature ranges for temperature-sensitive products; its guidance does not make one range universal. (WHO Technical Report Series No. 961, Annex 9, Supplement 8 (2011), cited in References.)

This is an example SOP for adaptation and approval. Local setpoints, clearances, schedules and acceptance limits below are not universal GMP or pharmacopoeial requirements.

Responsibilities

• Assigned user or analyst: Check the unit before use, follow the approved operating instructions, make required records and report alarms or excursions promptly.
• Quality Control Head or delegate: Ensure that the approved procedure, monitoring plan, calibration and qualification records, excursion assessments and staff training are in place.
• Engineering or service provider: Perform assigned maintenance and calibration under approved instructions and return the unit to service only after the required checks are complete.

Procedure

1. Checks before use

1. Confirm the refrigerator or freezer identification, service status, monitoring device status and current calibration status.

2. Check that the interior, shelves, door seal and visible surfaces are clean and undamaged. Clean using the approved site method and materials compatible with the unit and stored items.

3. Arrange the unit so that air can circulate and stored items do not obstruct the sensor or air outlet. Follow the equipment manufacturer’s installation and operating instructions.

   Example in-house criterion (not a pharmacopoeial requirement): Maintain at least 200 mm between the air outlet and the side wall.

2. Start-up and loading

1. Switch on the mains supply and confirm that the display and monitoring device operate normally.

2. Allow the unit to reach and maintain its approved operating range before loading. Check the temperature using the monitoring device identified in the approved procedure.

   Example in-house criterion (not a pharmacopoeial requirement): This example SOP specifies a 2–3 hour pre-loading run.

3. Example in-house criterion (not a pharmacopoeial requirement): This example SOP lists 2 °C to 8 °C for a refrigerator and −10 °C to −25 °C for a deep freezer. WHO’s technical supplement identifies 2 °C to 8 °C and −25 °C to −10 °C as examples of ranges that can apply, while explaining that permitted ranges vary. Set and approve limits based on the actual materials and intended use. (WHO TRS No. 961, Annex 9, Supplement 8 (2011))

4. Load items in the approved arrangement, leaving the circulation paths and monitoring point unobstructed. Close the door after loading.

5. Example in-house criterion (not a pharmacopoeial requirement): Keep door openings brief and limit avoidable access. WHO guidance says monitoring devices should be positioned to minimize the effect of transient events such as door opening. (WHO Technical Report Series No. 992, Annex 5, Supplement 6 (2015))

3. Temperature monitoring and excursions

1. Record the reading at the frequency defined in the approved site monitoring plan. This example refers to an annexed log but does not state a recording frequency; do not infer one from this template.
2. For products with specified labelled storage temperatures, WHO guidance calls for temperature mapping of the allocated storage space, which may include laboratories. The mapping protocol and report should document the study and its findings. (WHO TRS No. 961, Annex 9, Supplement 8 (2011))
3. Example in-house criterion (not a pharmacopoeial requirement): If the temperature is outside its approved range, notify the responsible Quality unit, document the event, identify affected materials and keep them under control pending a documented quality assessment. Use the approved procedure to determine disposition; a temperature excursion alone does not establish that material is acceptable or unusable.
4. Example in-house criterion (not a pharmacopoeial requirement): This example SOP calls for a temperature-distribution study yearly and after major modification or repair. Record the approved interval and event triggers in the site programme.

4. Calibration and qualification

1. Calibrate the temperature sensor and recording device under a written programme that defines instructions, intervals, accuracy limits and actions for results outside limits. Under 21 CFR 211.160(b)(4), instruments and recording devices must be calibrated at suitable intervals under such a programme, and devices that do not meet established specifications must not be used. (21 CFR 211.160(b)(4), current eCFR)
2. WHO’s technical supplement for fixed storage-area monitoring says electronic sensors should generally have accuracy of ±0.5 °C or better and should be calibrated annually. Apply that guidance within its scope and assess it against the equipment, intended use and applicable quality requirements. (WHO Technical Report Series No. 992, Annex 5, Supplement 6 (2015))
3. Example in-house criterion (not a pharmacopoeial requirement): This example SOP specifies yearly calibration by an approved external service provider and an acceptance criterion of ±2.0 °C for the digital controller and sensor. Record results, as-found and as-left status, traceability details, deviations and any corrective action.
4. WHO’s technical supplement on fixed storage-area monitoring describes mapping and qualification of storage areas and equipment, including IQ, OQ and PQ, before products are brought into storage. Qualify this unit and its monitoring arrangement for the intended use before storage. (WHO Technical Report Series No. 992, Annex 5, Supplement 6 (2015))
5. Example in-house criterion (not a pharmacopoeial requirement): Review qualification after repairs, modifications, repeated excursions or other changes that may affect performance. Use an approved protocol and document results and any required follow-up.

5. Cleaning, maintenance and records

1. Clean and maintain the unit according to the approved site procedure and the manufacturer’s instructions. Record maintenance, repairs, cleaning where required by the quality system, and return-to-service checks.
2. Example in-house criterion (not a pharmacopoeial requirement): The temperature log should identify the unit, date and time, measured value, person making the entry, and any alarm, excursion or action taken. Complete entries at the time of the activity, as described in EudraLex Volume 4, Part I, Chapter 4, §4.8, and correct them using the site’s controlled-record procedure. (EudraLex Volume 4, Part I, Chapter 4, §4.8 (2011))
3. For temperature or calibration records specifically associated with a product batch, retain the records at least one year after the respective batch’s expiry under 21 CFR 211.180(a). For EU GMP batch documentation, retain it for one year after batch expiry or at least five years after Qualified Person certification, whichever is longer, under EudraLex Volume 4, Part I, Chapter 4, §4.11. Apply longer product-specific or local requirements where applicable. Other equipment records follow the approved retention schedule. (21 CFR 211.180(a), current eCFR; EudraLex Volume 4, Part I, Chapter 4, §§4.10–4.11 (2011))

Training and distribution

Example in-house criterion (not a pharmacopoeial requirement): Train assigned users on the approved procedure, temperature recording, alarms and excursion reporting before they use the unit. Keep the controlled copy and any associated log forms in the locations specified by the site’s document-control system.

Frequently asked questions

Are 2 °C to 8 °C and −10 °C to −25 °C required for every QC refrigerator or freezer?

No. WHO TRS No. 961, Annex 9, Supplement 8 (2011) lists these as examples of possible ranges and says permitted ranges vary. The approved storage specification for the materials and the unit’s qualification must determine the actual limits.

Does GMP require calibration every year?

21 CFR 211.160(b)(4) requires calibration at suitable intervals under an established written programme; it does not set a universal annual interval. WHO’s fixed-storage monitoring supplement recommends annual sensor calibration in its stated scope. The site’s approved programme should define the applicable interval.

How long should batch-associated temperature records be kept?

At least one year after the respective batch’s expiry. EU GMP Chapter 4 requires one year after expiry or at least five years after Qualified Person certification, whichever is longer; see §5 above for the sources.

See also

• SOP for recording temperature, relative humidity and pressure differential
• Temperature and relative humidity monitoring in the pharmaceutical industry
• SOP for recording temperature and humidity of a stability chamber

References

• World Health Organization. WHO Expert Committee on Specifications for Pharmaceutical Preparations: Forty-fifth report. WHO Technical Report Series No. 961, Annex 9, Supplement 8, “Temperature mapping of storage areas” (2011). Official WHO PDF.
• World Health Organization. WHO Expert Committee on Specifications for Pharmaceutical Preparations: Fiftieth report. WHO Technical Report Series No. 992, Annex 5, Supplement 6, “Temperature and humidity monitoring systems for fixed storage areas” (2015). Official WHO PDF.
• United States. 21 CFR Part 211, current eCFR as accessed 19 October 2026, §§211.160(b)(4) and 211.180(a). Calibration provision; records retention provision.
• European Commission. EudraLex Volume 4, EU Guidelines for Good Manufacturing Practice, Part I, Chapter 4, “Documentation” (2011 revision), §§4.10–4.11. Official European Commission PDF.