Validate Temperature Monitoring Equipment

As part of an effective HACCP plan, temperature thermometers need to be regularly validated to ensure that they are operating accurately. Especially within the food industry, it is essential that temperature monitors produce accurate readings and ensure food is stored and cooked safely. The consequences of an incorrect reading can have a highly damaging effect, for both the consumer and the business.

The SALSA requirement for temperature calibration states that:

“Environment monitoring devices, such as temperature monitoring equipment and process control devices such as weighing equipment identified as essential for legality and food safety shall be calibrated to ensure accuracy within agreed parameters at a determined frequency.”


There are a number of methods that can be taken to verify the accuracy of temperature monitoring equipment.

Most temperature monitors are issued with a certificate of calibration, which is usually valid for a year. These thermometers can be used as a comparator to verify the accuracy of other thermometers. If the thermometer produces the same reading as the one with a valid certificate, this establishes that the thermometer is reporting accurately.

Alternatively, thermometers can be verified by creating environments in which the temperature is already known. Two ways of doing this, is to place the thermometer in icy water, or boiling water (instructions below).

Icy Water

  1. Fill a glass with ice cubes, then top off with cold water.
  2. Stir the water and let sit for 3 minutes.
  3. Stir again, then insert your thermometer into the glass, making sure not to touch the sides.
  4. The temperature should read 0°C. Record the difference and offset your thermometer as appropriate.

Boiling Water

  1. Boil a pot of distilled water.
  2. Once the water has reached a rolling boil, insert your thermometer, making sure not to touch the sides or bottom of the pot.
  3. The temperature should read 100°C. Record the difference and offset your thermometer as appropriate.


Another method of ensuring accurate thermometer results is to send the instrument off to be calibrated. To calibrate a temperature monitor it needs to be tested and adjusted by a qualified agent. Calibration usually comes with an accompanying certificate.

It can be most cost effective to have one instrument calibrated that is then used as a comparator to verify the accuracy of other monitoring devices.


It is essential that records are kept of all verification and calibration exercises. These records can be used to demonstrate food safety compliance for third party audits such as BRC or SALSA.

For more information on verification and calibration of temperature monitoring equipment, talk to an expert on 08450 267 745. Take a look at our full range of temperature monitoring equipment here.

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