Do you know the How Do You Calibrate a Thermometer? Calibrating a thermometer may be a simple, but necessary process.
If you’re anything like me, you’ve probably got a couple of thermometers dancing around your drawer of miscellaneous kitchen tools. But are they accurate?
If you’re roasting a turkey, a degree or two of inaccuracy isn’t getting to make a dramatic difference. How do you calibrate a thermometer in general? Keeping read!
But, if you’re making caramel, tempering chocolate, cooking sous videos, grilling a steak, or doing any number of other tasks that need a particular temperature, having a thermometer you’ll trust is clutch.
Calibrate a Thermometer
Calibrating your thermometer is quick and easy. Many analog and digital thermometers allow you to offset the temperature to regulate the calibrated value.
However, if your thermometer doesn’t offer an offset function, a bit of blue tape with the delta will work just fine.
Calibrating a thermometer is the process of checking and adjusting its accuracy to ensure that it provides accurate temperature readings. Over time, thermometers can drift from their original calibration due to factors such as wear and tear, exposure to extreme temperatures, or improper handling. Calibration is important in various settings where temperature accuracy is critical, such as in scientific laboratories, food service establishments, healthcare facilities, and industrial processes.
Calibrating a thermometer typically involves comparing its readings against a known reference temperature, such as a standard thermometer or a calibrated temperature source, and making adjustments if necessary. The specific method for calibrating a thermometer depends on its type and design, but it generally involves the following steps:
Preparing the reference temperature
The reference temperature source or standard thermometer used for comparison should be properly calibrated and stabilized to a known temperature.
Comparing readings
Place the reference temperature source and the thermometer being calibrated nearby, ensuring that they are exposed to the same temperature. Allow them to stabilize for a sufficient period, and then compare the readings of the two thermometers.
Adjusting if necessary
If the readings of the thermometer being calibrated deviate from the known reference temperature, adjustments may be needed. Some thermometers have a calibration screw or knob that can be adjusted to bring the readings in line with the reference temperature. Others may require professional calibration by a qualified technician.
Verification
After making adjustments, recheck the readings of the calibrated thermometer against the reference temperature to ensure that they match within an acceptable tolerance.
Documentation
Record the calibration results, including the date, reference temperature used, and any adjustments made, in a calibration log or certificate for traceability and quality control purposes.
Method 1: ICE Water
1. Fill a glass with ice cubes, and then top off with cold water
2. Stir the water and let sit for 3 minutes
3. Stir again, and then insert your thermometer into the glass, making sure not to touch the sides
4. The temperature should read 32°F (0°C). Record the difference and offset your thermometer as appropriate
Method 2: Boiling Water
1. Boil a pot of distilled water
2. Once the water has reached a rolling boil, insert your thermometer, making sure not to touch the sides or bottom of the pot
3. The temperature should read 212°F (100°C). Record the difference and offset your thermometer as appropriate
Why It’s Important to Calibrate Your Thermometer
Calibration gives you the peace of mind of knowing the temperature you’re reading is the correct temperature of the media you’re measuring.
That can be extremely important for procedures that require precise temperature control, including industrial chemical processes and food preparation.
Many cities and state health departments have food storage guidelines with strict temperature ranges which edibles can’t deviate from. Beyond the regulations, you don’t want anyone to get sick because your thermometer said your pork ribs were 145° F once they were only 110° F.
That is an extreme example. A thermometer that far off of the register would likely need to be replaced. A thermometer should register within 2° F of actual temperature to be considered accurate. That is 1.1° C.
Testing should be done regularly, counting on the frequency of use and therefore the thermometer’s purpose. Thermometers used for processes that require precise measurements should be tested daily or weekly. If a thermometer goes out of calibration often. The replacement may be necessary.
How do You Calibrate a Thermometer
There are a couple of alternative ways to calibrate digital and bi-metal thermometers.
The most common are comparison boiling and freezing. There also are thermometer calibration services that will do that for a price.
The liquid in glass thermometers should be sold by direct material. Feature an adjustment screw on the rear of the dial. Note that, if your thermometer doesn’t have an adjusting nut (or calibration screw, etc., usually found on the rear of the thermometer, you’ll need to send it to one of these services for re-calibration.
The duration choice bi-metal thermometers we sell have an optional calibration dial located on the rear of the dial case. The first and simplest method is by using comparison.
That is, compare the thermometer you think might need re-calibration to a thermometer that has already been calibrated or that has been a national Institute of Standards and Technology (NIST) certified.
This is Why a NIST-Certified Thermometer
This method is often effective, goodbye as you’re confident that the comparison thermometer is reading correctly. This is why a NIST-certified thermometer, tested annually, is preferable.
Just compare the 2 and adjust the thermometer you’re calibrating to match the “correct” thermometer’s temperature.
This should do with distilled water, as tap water has compounds in it which could affect the freezing or melting points of water and skew the process.
Calibration ice water or “Freezing” thermometer is best for thermometers used to measure low temperatures.
Add crushed ice to a bowl or cup of water to make a slushy mix a minimum of 2” deep. Insert the thermometer stem into the slushy mix, for at least one minute.
Make sure the stem does not come into contact with the sides or bottom of the container. The thermometer should read believe 30 and 34° F. if it doesn’t adjust the dial to 32° F.
To calibrate a thermometer won’t measure higher temperatures. You might prefer the boiling method. Again, use distilled water and bring it to a rolling boil in a pot or breaker if you have one handy.
Insert the thermometer’s stem a minimum of 2” into the water for a few minutes, taking care to not burn you while doing this. Do not let the stem touch the edges or bottom of the container.
The thermometer should read between 210 and 214. If it does not, adjust the dial to 212F.
That boiling point is at sea level. But since the boiling point changes at different altitudes, you will need to consult a chart like this one to determine the correct boiling point for your elevation. You can find your elevation here.
(FAQs)
Q: What does it mean to calibrate a thermometer?
A: Calibrating a thermometer means adjusting it to ensure that it is measuring temperature accurately and providing reliable readings. It involves comparing the thermometer’s readings to a known standard or reference thermometer and making adjustments if necessary.
Q: Why is it important to calibrate a thermometer?
A: It is important to calibrate a thermometer to ensure accurate temperature measurements. Temperature is a critical parameter in various applications, such as food safety, medical care, scientific research, and industrial processes. An inaccurate thermometer can lead to incorrect results, which can have serious consequences, such as foodborne illnesses or compromised scientific experiments.
Q: How often should I calibrate my thermometer?
A: The frequency of calibration depends on the type of thermometer and its intended use. As a general guideline, thermometers used for critical applications, such as in food service or medical care, should be calibrated more frequently, ideally before each use or at least once a month.
Other thermometers used for less critical applications may require calibration at regular intervals, such as every 3-6 months or annually. It is important to refer to the manufacturer’s instructions and industry guidelines for specific recommendations.
Q: How can I calibrate a thermometer?
A: The calibration method depends on the type of thermometer. Here are some common methods:
Ice bath method: Fill a container with crushed ice and add a small amount of water. Stir the mixture to create a slurry. Insert the thermometer probe into the slurry, avoiding contact with the container, and wait for the reading to stabilize. The temperature should read 0°C (32°F), which is the freezing point of water.
Boiling water method: Bring a pot of water to a rolling boil and insert the thermometer probe into the water, avoiding contact with the pot. Wait for the reading to stabilize. The temperature should read 100°C (212°F) at sea level, or adjust for altitude if necessary.
Comparison method: If you have access to a calibrated reference thermometer, you can compare its readings with the thermometer being calibrated. If there is a discrepancy, you may need to adjust the calibration of the thermometer being calibrated based on the difference between the two readings.
Q: What should I do if my thermometer cannot be calibrated or is consistently inaccurate?
A: If your thermometer cannot be calibrated or is consistently inaccurate, it may need to be replaced or repaired. Some thermometers, especially digital ones, have a limited lifespan and may need to be replaced periodically. Contact the manufacturer or a qualified technician for further assistance.
Q: Are there any additional tips for calibrating a thermometer?
A: Yes, here are some additional tips for calibrating a thermometer:
1. Allow the thermometer to stabilize in the calibration environment for a few minutes before taking a reading.
2. Avoid touching the probe or the thermometer housing with your hands, as it can affect the temperature reading.
3. Keep the thermometer probe clean and free from debris to ensure accurate measurements.
4. Store the thermometer properly when not in use, following the manufacturer’s recommendations.
5. Keep a record of calibration dates, results, and adjustments made for documentation and traceability purposes.
Final Thoughts
Calibrating a thermometer is a critical step in ensuring accurate temperature measurements. Always refer to the manufacturer’s instructions and use a certified reference thermometer for the most reliable results. Regular calibration, proper handling, and following best practices will help you maintain accurate temperature readings and ensure the safety and well-being of those relying on your thermometer measurements.
When a change of this type does take place, the indication of the thermometer will also change. Re-calibration of the certified thermometer updates the indications and thus allows the user to maintain accurate, reliable, and consistent results when making temperature measurements.
Even if your thermometer can’t be calibrated, you can – and should – use these methods to check its accuracy and ensure that you’re getting a proper temperature read on your food. Follow the manufacturer’s instructions for taking temperatures. Always calibrate a new thermometer, one that has been dropped on a hard surface.
