LimsPulse
Hot air oven · Calibration procedure

Temperature accuracy

Compares the oven's displayed temperature with a calibrated reference thermometer at the set points used in the lab.

Photo of a Hot air oven
Photo: Karelj, Public domain (cropped), via Wikimedia Commons
PURPOSE

Why this is checked

LOD and drying results depend on the actual temperature. If the display reads differently from the chamber, samples may be under- or over-dried.

Frequency

Typically every 6 or 12 months, and after repair, as defined in your calibration SOP.

Learn how the Hot air oven works
YOU WILL NEED

Standards & tools

  • Calibrated digital thermometer or data logger with a probe, traceable to national standards (resolution 0.1 °C)
BEFORE YOU START

Prerequisites

  • Empty, clean oven
  • Probe placed at the centre of the chamber near the controller sensor, not touching any surface
  • Probe lead routed so the door seals properly
PROCEDURE

Step by step

  1. 1Set the oven to the first set point (for example 60 °C) and allow it to stabilise for at least 30 minutes after reaching it.
  2. 2Record the displayed and reference temperatures several times over about 15 minutes and take the mean.
  3. 3Repeat at each working set point (for example 105 °C and 150 °C).
RECORD

Example observation table

Set (°C)Display (°C)Reference (°C)Difference (°C)
6060.060.8+0.8
105105.0104.1−0.9
150150.0151.3+1.3
CALCULATION

How to calculate the result

Difference = Reference reading − Set temperature
  1. Set 105 °C, reference 104.1 °C
  2. Difference = 104.1 − 105 = −0.9 °C (within ±2 °C)
ACCEPTANCE CRITERIA

Pass if

  • Reference reading within ±2 °C of the set temperature (use the limit in your SOP; LOD at 105 °C is commonly required within ±2 °C).
IF IT FAILS

What to do

  • Check probe position and door seal, then repeat.
  • Adjust the controller offset as per the manufacturer's procedure and repeat.
  • If it still fails, label the oven 'Out of calibration' and assess LOD results since the last pass.
MORE

Other Hot air oven 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.

See how