Guide to thermometer calibration and frequency of calibration.
Thermometers should be calibrated:
Recommended best practice:
Have your thermometer calibrated or obtain a new thermometer with a IANZ endorsed calibration certificate. This calibration certificate needs to include calibration points that cover the temperature range over which the thermometer will be used.
Carry out your own basic single point check frequently. This can be a simple comparison with another thermometer or a check using a container of finely crushed wet ice that has had the excess water drained off. (Thermometer should read 0.0 °C). Compare result to the ice point reading on the latest calibration certificate.
Have the thermometer calibrated every 12 months and a new IANZ endorsed certificate issued.
Prior to first use
After an instrument has been repaired or modified
When a specified time period has elapsed
Whenever observations appear questionable or instrument indications do not match other instruments
As specified by a requirement, e.g. customer specification, instrument manufacturer recommendation, auditor requirement.
The appropriate calibration frequency for your device needs to be determined by several factors such as quality assurance requirements, regulatory requirements and operating environment.
Common problems with thermometers:
Thermometers used in food processing, food service and manufacturing environments are subject to knocks, drops, moisture, calibration drift and general wear and tear from multiple users.
The most common causes of reading errors in digital thermometers used in these environments are from moisture ingress, physical damage and calibration drifting.
Obvious physical damage can easily be identified by visual inspection but often the damage can be internal and therefore not visible to the user.