Water bath · Calibration procedure
Temperature accuracy and uniformity
Measures the water temperature at several positions with a calibrated reference thermometer to check how close the bath is to its set point and how even it is.
PURPOSE
Why this is checked
Tests that depend on temperature (e.g. keeping agar molten or incubating a reaction) need the bath to be at the right temperature everywhere samples are placed.
Frequency
Typically every 6 or 12 months at the set points used in methods, as defined in your calibration SOP.
Learn how the Water bath worksYOU WILL NEED
Standards & tools
- Calibrated reference thermometer or multi-channel probe logger, traceable to national standards
BEFORE YOU START
Prerequisites
- Bath filled to the normal level and lid in place
- Bath stable at the set point for at least 30 minutes
PROCEDURE
Step by step
- 1Choose the set points used in methods (e.g. 37 °C and 45 °C).
- 2Place the reference probe at five positions: four corners and the centre, at sample depth.
- 3Allow each reading to stabilise, then record the reference reading and the bath display.
- 4Calculate the mean (accuracy) and the spread between positions (uniformity).
RECORD
Example observation table
| Position | Reference (°C) | Display (°C) |
|---|---|---|
| Front left | 36.8 | 37.0 |
| Front right | 37.1 | 37.0 |
| Rear left | 36.9 | 37.0 |
| Rear right | 37.3 | 37.0 |
| Centre | 37.0 | 37.0 |
CALCULATION
How to calculate the result
Accuracy = Mean reference − Set point; Uniformity = Maximum − Minimum reference reading
- Set point 37.0 °C
- Mean = (36.8 + 37.1 + 36.9 + 37.3 + 37.0) ÷ 5 = 185.1 ÷ 5 = 37.02 °C
- Accuracy = 37.02 − 37.0 = +0.02 °C
- Uniformity = 37.3 − 36.8 = 0.5 °C
ACCEPTANCE CRITERIA
Pass if
- Each position typically within ±1 °C of the set point (tighter, e.g. ±0.5 °C, where a method requires).
- Uniformity as defined in your SOP.
IF IT FAILS
What to do
- Label the bath and stop using it for temperature-critical tests.
- Check water level, circulation and controller; service and repeat.
In LimsPulse · Calibration Management
LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.