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Thermometer Information

The California Retail FoodCode requires every food facility to have an accurate easily readable probe thermometer suitable for measuring the temperature of food readily available on the premises. There are several types of thermometers available for use including:

Bimetallic Thermometers
 Cost about $10. The most common foodservice thermometer in use today. They are inexpensive but require frequent calibration (see calibration procedures below). Since the sensor is located 2 inches or more from the tip, they are not practical for use on thin foods like hamburger patties.

Thermister Digital Thermometers
 Slightly more expensive than bimetallic thermometers ($10-$30) but are much faster reading. This type of thermometer registers temperature at the tip of the probe and can accurately measure temperatures of small and thin foods.

Thermocouple Thermometers
 Costs range from $100-$650. Very fast registering and accurate thermometers. Results are displayed digitally. Most models have interchangeable probes for a variety of uses. The more sophisticated units allow storage of temperature data which can be downloaded onto a computer.

Infrared Thermometers
 Costs range from $150-$400. This type of thermometer uses a laser beam to detect the amount of radiant energy emitted by an object. Infrared thermometers are limited in that they only measure the surface temperature of an object but can be used to monitor display cases, salad bars and other foods.

How to Calibrate a Bimetallic Thermometer

The Ice Method: Immerse the temperature probe at least two inches into a glass of finely crushed ice. Add cold tap water to remove air pockets. Wait at least 1 minute. The gauge should read 32 degrees F. If it does not, turn the adjustment nut on the back of the reading dial with a pair of pliers until the dial reads 32 degrees F. Wait at least 1 minute to verify correct adjustment.

The Boiling Method: Submerge the probe into boiling water. Wait until the needle stops moving, then adjust the calibration nut until the dial reads 212 degrees F. Since the boiling point of water decreases as altitude increases, this method may not be as accurate as the ice method at altitudes above sea level unless the exact boiling point temperature is known.

How to Calibrate a Digital Thermometer

The following are links to two well known providers of thermometers and related equipment:

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