A thermometer is usually calibrated using two approaches: the ice point method and the boiling point method. This temperature measuring deviceÂ must be calibrated daily if repeatedly used. Otherwise, a thermometerÂ should be adjusted prior to itsÂ initial usage, when switching from one temperature to another or every time itÂ is dropped.
In certain industries, particularly in the food processing sector, calibrating a thermometer is essential to ensure accurate temperature readings. The inexpensive and simplest methods of utilizing ice water and boiling water are widely used in adjusting a thermometer.
Ice point method
The first step when using this technique is to fill a container with crushed ice and clean tap water. After stirring, the thermometer probe is then placed in the solution, with the sensing area fully immersed for a minimum of 30 seconds or until the indicator has stopped moving. Extra care should be taken in preventing the stem from coming into contact with the sides or bottom of the container. With the probe still submerged, the thermometer is adjusted until it reads 32 degrees Fahrenheit. In the case of a digital thermometer, pressing the reset button automatically adjusts the device.
Boiling point method
The same basic steps in the ice point method are taken when using the boiling point technique, except that the thermometer stem is submerged in boiling water, and then adjusted to a reading of 212 F.