Thermometer Calibration Procedure and Uncertainty Measurement

Procedure for Calibrating Thermometers, Sample Datasheet and Uncertainty Calculation

Objective: To calibrate a digital thermometer against a reference thermometer and calculate the measurement uncertainty.

Materials Needed:

1. Digital thermometer to be calibrated (Thermometer A)
2. Reference thermometer with known accuracy (Thermometer B)
3. Crushed ice
4. Boiling water
5. Containers for ice baths and boiling water
6. Timer
7. Calibration certificate for Thermometer B (for uncertainty source information)

Calibration Procedure:

1. Preparation:

   • Ensure Thermometer B has been recently calibrated by a certified calibration laboratory.
   • Verify that both thermometers are clean and in good condition.

2. Ice Bath Calibration:

   • Prepare an ice bath by mixing crushed ice and a small amount of water in a container.
   • Allow the ice bath to stabilize for a few minutes.
   • Immerse the sensors of both Thermometer A and Thermometer B into the ice bath, ensuring they are fully covered and not touching the sides or bottom of the container.
   • Allow the readings to stabilize for a few minutes.
   • Record the readings from both thermometers.

3. Boiling Water Calibration:

   • Bring a container of water to a rolling boil, ensuring it's at the boiling point (100°C or 212°F at sea level).
   • Immerse the sensors of both thermometers into the boiling water, fully submerged and not touching the container.
   • Allow the readings to stabilize for a few minutes.
   • Record the readings from both thermometers.

4. Thermometer Calibration Sample Datasheet:

   Calibration Date:	August 8, 2023
   Reference Thermometer:	Model: RT-100
   	Serial No.: 12345
   	Calibration Date: July 15, 2023
   Thermometer to be Calibrated:	Model: T-200
   	Serial No.: 67890
   Calibration Procedure:	Ice Point and Boiling Point
   Ambient Temperature:	22°C
   Altitude (if applicable):	0 meters above sea level

   Ice Point Calibration:

   Reference Thermometer	Thermometer to be Calibrated
   Ice Bath Temperature:	Ice Bath Temperature:
   Reading: -0.1°C	Reading: -0.3°C

   Boiling Point Calibration:

   Reference Thermometer	Thermometer to be Calibrated
   Boiling Water Temperature:	Boiling Water Temperature:
   Reading: 100.2°C	Reading: 99.8°C

5. 
   

6. Thermometer Uncertainty Calculation:

   • Obtain the uncertainty information from the calibration certificate of Thermometer B.

   • The uncertainty of Thermometer B is typically provided as an expanded uncertainty with a coverage factor (k) of 2. This means that the uncertainty range is estimated to cover about 95% confidence.

   • Calculate the expanded uncertainty (U) of Thermometer B's readings using the formula:

   • U(Tb) = k * (standard uncertainty from certificate)

   • The combined uncertainty (Uc) when comparing the readings of Thermometer A and Thermometer B can be estimated as the square root of the sum of their individual uncertainties squared:

   • 
     

   • Uc = √(U(Ta)^2 + U(Tb)^2)

7. 
   

   • Compare the readings of Thermometer A and Thermometer B at both the ice bath and boiling water points.
   • If the difference between the readings is within acceptable limits and falls within the combined uncertainty range, Thermometer A is considered calibrated against Thermometer B.
   • If adjustments are needed, follow the manufacturer's instructions for calibration adjustments.

Please note that in a real calibration scenario, the values for readings and uncertainties would be actual measurements specific to the thermometers used. The example provided serves as a template for the calibration process and uncertainty calculation. The actual uncertainty estimation may involve more complex calculations, depending on the details provided in the calibration certificate and the specific calibration process used by the laboratory.