1. Thermometer Calibration & Use
Shannon Rohall
Stevie Arroyo

2. Learning Objectives Define thermometer calibration
Describe the different methods of calibration.
Explain anatomy of thermometer and different types of thermometers.
Describe how to properly use a thermometer.

3. Thermometer Calibration
Definition: Calibrating is checking the thermometer for accuracy against a standard (such as ice water) to confirm that it is currently giving a correct reading.
Why necessary?
Thermometers can easily be thrown off mark.
Thermometers help to make
sure your food is cooked to a
high enough temperature to
kill harmful bacteria and viruses.

4. Methods of Calibration
Ice Point Method (most common)

5. How to Calibrate using Ice Point Method
Fill a large glass with finely crushed ice.
Add clean water to the top of the ice and stir well.

6. How to Calibrate using Ice Point Method
Immerse the thermometer stem a minimum of 2 inches into the mixture.
The thermometer should read 32 °F after 30 seconds.

7. Methods of Calibration
Boiling Point Method
Uncommon due to risk of burn injury.
Bring water in a deep pan to a full rolling boil.

8. How to Calibrate using Boiling Point Method
Immerse the stem of a thermometer 2 inches into the boiling water.
The thermometer should read 212 °F after 30 seconds.

9. Methods of Calibration: How to Correct an Error
If your thermometer does not read
correctly after 30 sec. :
Hold the adjusting nut with a wrench or other tool.
Rotate thermometer
head until its shows
correct reading.

10. Recap

11. Bimetallic Stemmed Thermometer
Types of Thermometers
Bimetallic Stemmed Thermometer
Most common and versatile
Sensing area is from the tip to a half-inch past the dimple
Easy-to-read temperature on the dial face

12. Types of Thermometers Thermocouple
- Measure temp with metal probe or sensing area.
- Displays results digitally.
- Come with interchangeable probes for liquids, flat cooking equip. and food.

13. Identification of Thermometer
Proper Use
Calibrate regularly and keep consistent records
Thermometer Calibration Log
Instructions: Check and calibrate all bi-metallic stemmed (instant-read) thermometers in this facility every two weeks and any time a thermometer is dropped or bumped. Maintain this log for a minimum of two years and until given permission to discard it. If corrective action is required, explain the action taken in the last column.
Number of Stem Thermometers in Facility: __________
Identification of Thermometer
Date
(of Calibration)
Temp. When Placed in Ice
Calibrated By (Food Service Worker’s Initials)
Corrective Action

14. Where would you place the thermometer?
Proper Use
Where would you place the thermometer?
Into the center or thickest part & away from any bones

15. How would you test soups temperature?
Proper Use
How would you test soups temperature?
Take it off the stove.
Stir and then insert probe into center of pot.

16. Proper Use
Clean and sanitize between uses to prevent cross contamination.
One of the following can be used to sanitize:
Boiling water
Sanitizing solution
One use alcohol swabs

17. Recap
DEMO

18. Proper Use Key points to remember:
Take the temperature of a product in several places, particularly irregularly shaped items.
Stir product before taking temperature.
Place stem or probe in the thickest part of the food item.

19. Proper Use
Do not rest the stem or probe on a bone – this may give an inaccurate reading.
Make sure entire sensing area is completely submerged in the food.
Never use mercury-filed glass thermometers
Wait for reading to steady (usually 15 sec.)

20. Review Questions
What is the most common type of thermometer used to test food temp?
Bimetallic stemmed thermometer
What temp. should your thermometer read after 30 sec. in ice water?
32 degrees Fahrenheit

21. Review Questions How & when should you sanitize your thermometer?
Sanitize probe using boiling water, sanitizing solution, or single use wipes.
Sanitize probe between uses

22. References
_Thermometers/index.asp