Thermometer Calibration
Thermometers used in food business must be checked at least twice a year to ensure that it is accurate. This is called calibration. Calibration of a thermometer can be done by external providers or done by business internally.
Internal calibration procedure is as follows:
Low temperatures: Place tip of thermometer probe into crushed ice and a little cold water - wait for the display to stabilise then measure reading (it should be between -0.5°C and + 0.5°C).
High temperatures: Place tip of thermometer probe into the steam from a boiling kettle of water, wait for the display to stabilise and record reading (it should be between 99.5°C and 100.5°C).
If the thermometer is faulty, either replace it or return it to the manufacturer/supplier for external calibration. In this event, a back-up thermometer is required. (New thermometers are normally considered to be accurate for a year from date of purchase).
Besides regularly checking the accuracy of the temperature probes in use, an accuracy check should also be carried out in the event that the food business operator suspects that a reading is not correct or if the temperature probe has been damaged in any way.
Records of all accuracy checks/internal calibrations should be maintained by the food business operator.
In the event that the accuracy checks identify that the temperature probe is no longer correct, it shall be removed from use and replaced by a calibrated probe. The food business operator must assess the risk to safety of all food produced while using the faulty temperature probe, and implement corrective action if necessary.
