Incubator · Calibration procedure
Temperature mapping
Places calibrated data loggers at several positions across all shelves to find hot and cold spots and prove the whole usable chamber stays within the incubation range.
PURPOSE
Why this is checked
Temperature varies between the top, bottom, front and back of a chamber. Mapping proves that every position where plates are placed is within the method range and identifies a representative location for the monitoring probe.
Frequency
At initial qualification, then typically annually, and after relocation, major repair or a change in loading, as defined in your SOP.
Learn how the Incubator worksYOU WILL NEED
Standards & tools
- Calibrated temperature data loggers or thermocouples (commonly 9 for small chambers, 15 or more for larger ones), traceable to national standards
BEFORE YOU START
Prerequisites
- Temperature accuracy calibration passed
- Mapping protocol approved, defining probe positions, duration and loading (empty and/or loaded)
PROCEDURE
Step by step
- 1Place loggers at the corners and centre of the top, middle and bottom shelves (e.g. 9 positions), away from walls.
- 2Close the door and let the chamber stabilise at the set point.
- 3Record every logger at a fixed interval (e.g. every 1–5 minutes) for at least 24 hours, or as per protocol.
- 4Include a door-opening test (e.g. open for 1 minute) and record the recovery time.
- 5Calculate the mean, minimum and maximum for each logger and the overall spread.
RECORD
Example observation table
| Logger | Position | Mean (°C) | Min (°C) | Max (°C) |
|---|---|---|---|---|
| T1 | Top front left | 32.6 | 32.2 | 33.0 |
| T2 | Top rear right | 32.9 | 32.5 | 33.3 |
| T3 | Top centre | 33.1 | 32.7 | 33.5 |
| T4 | Middle front left | 32.4 | 32.0 | 32.8 |
| T5 | Middle centre | 32.8 | 32.4 | 33.2 |
| T6 | Middle rear right | 33.3 | 32.9 | 33.7 |
| T7 | Bottom front left | 32.7 | 32.3 | 33.1 |
| T8 | Bottom centre | 33.0 | 32.6 | 33.4 |
| T9 | Bottom rear right | 32.5 | 32.1 | 32.9 |
CALCULATION
How to calculate the result
Uniformity (spread) = Highest logger mean − Lowest logger mean; Overall mean = Σ logger means ÷ number of loggers
- Set point 32.5 °C; logger means range from 32.4 °C (T4) to 33.3 °C (T6)
- Spread = 33.3 − 32.4 = 0.9 °C; overall mean = 295.3 ÷ 9 = 32.8 °C
- All individual readings between 32.0 and 33.7 °C, inside the 30–35 °C range: Pass
- Hot spot T6 (middle rear right) and cold spot T4 (middle front left) recorded for routine monitoring
ACCEPTANCE CRITERIA
Pass if
- Every reading at every position within the required incubation range (e.g. 30–35 °C or 20–25 °C).
- Spread between logger means typically not more than 2.0 °C, or as defined in your SOP.
- Recovery to the range within the time stated in the protocol after a door opening.
IF IT FAILS
What to do
- Restrict use to positions that passed, and mark failing positions as not for use, or stop using the incubator.
- Check the fan, door seal and loading pattern; service the unit if needed.
- Repeat the mapping after correction and assess tests incubated in failing positions.
MORE
Other Incubator calibrations
In LimsPulse · Calibration Management
LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.