Following HACCP food safety regulations is essential in ensuring that the food you serve to your customers is both safe and consistently high quality, as well as fundamental in legally protecting your business with accurate records. As we work with a number of businesses in …
In the last blog post within our infrared thermometer series, we looked at how to correctly validate the accuracy of your instrument using a Thermometer Comparator. The comparator method allows devices to be validated at ambient room temperature, however we would not recommend conducting it …
The third instalment in our infrared thermometer series is about how to correctly validate the accuracy of an IR device in the field. Our first post looked at emissivity and how to get an accurate reading, while the second focused on how to clean and store an IR thermometer. If you haven’t already, we recommend also reading these posts in order to fully understand how infrared works before attempting calibration.
Calibration vs validation
The process of calibrating a thermometer can only be completed in a controlled laboratory environment. The process of validation, where an instrument is comparison checked for accuracy, is what is described here. If the reading of an instrument is found to be inaccurate when validated using a calibrated thermometer it must then be sent to a laboratory to be repaired or recalibrated.
Why validating a temperature on an IR instrument is different to calibrating a penetration probe
Infrared thermometers only measure surface temperatures and should therefore only be used as a quick guide. This is because the accuracy of the measurement is affected by many factors and variables such as the emissivity of the surface, type of material, transparency, colour and reflectivity (read our full guide to getting accurate IR readings here). An infrared thermometer must be validated against a laboratory calibrated ‘master’ thermometer on a known temperature source. The best way to control the emissivity and temperature of a surface, ensuring that you get the true reading of an infrared thermometer, is by using a solid black body. This minimises most external factors and prevents the temperature from changing too quickly.
As seen in our previous blog post on the accuracies and limitations of infrared, emissivity plays a huge role when calibrating IR thermometers.
Depending on what you’re pointing your infrared thermometer at you’re going to get a variation in emitted infrared energy. Emissivity is a measure of a material’s ability to emit infrared energy. It is measured on a scale from just about 0.00 to 1.00. Generally, the closer a material’s emissivity rating is to 1.00, the more that material tends to absorb reflected or ambient infrared energy and emit only its own infrared radiation. Click here to learn more about emissivity.
What equipment is required to validate the accuracy of an IR instrument
Here at ETI we have specifically designated laboratories for our calibration of infrared thermometers. We have put a lot of time and resources into ensuring that the temperature and humidity is exactly right for each process to begin. We also have controlled hot and cold black body sources in order to achieve the accuracies stated within the product’s specification. We are able to provide a traceable certificate of calibration on all ETI manufactured infrared thermometers.
In order to check the accuracy of an IR thermometer out in the field, a Thermometer Comparator and high-accuracy, calibrated ‘master’ thermometer such as a Reference Thermometer are required. The thermometer comparator consists of an aluminium cup with a solid matte black base. The base incorporates two holes for taking the internal temperature of the base using a ‘master’ thermometer. An infrared thermometer can then be held above the entrance of the cup to take the temperature of the surface of the base.
How to validate a temperature on an IR instrument
Ensure the comparator and infrared thermometer are clean and free of any debris or substances that could affect the reading (read our full guide to cleaning and storing your IR device here).
Place the thermometer comparator on a flat surface.
Insert the Reference Thermometer probe into one of the base test holes and allow it to stabilise. This could take any amount of time, depending on the response time of the inserted probe.
If the IR device has adjustable emissivity, ensure it is set to 0.95, the correct setting for the matte black surface of the Thermometer Comparator.
Point the thermometer straight down into the bottom of the comparator and take a measurement. The instrument should read within 1 °C of the Reference Thermometer at 22°C ambient room temperature, depending on the accuracy of the thermometer.
What temperature can an IR instrument be validated at
The accuracy of an infrared thermometer can be checked using a comparator at any stable temperature. However, to reduce the possibility of a difference in temperature between the inside surface and the base test hole, it is more accurate at 22°C, ambient room temperature.
Using an IR thermometer at hot or cold temperatures will increase the possibility of thermal instability.
For every 1°C the environment is above or below 22°C (ambient temperature), an adjustment factor should be added to the instrument’s accuracy to allow for the thermal instability. Typically this is 0.05°C for RayTemp thermometers. Other infrared thermometers may have a different value. Here is a table showing the values that need to be considered when using a RayTemp 2 thermometer in cold or hot environments.
*accuracies and thermal stability for other instruments can vary.
Dos and don’ts
Do calibrate at an ambient temperature of approximately 22°C if possible.
Don’t change the temperature surrounding the comparator before validation or the surface temperature may differ from the internal temperature.
Do be aware of the external factors that influence taking a correct IR reading from the comparator, such as moisture, frost and debris.
Don’t position the infrared thermometer too far away, or at an angle, when taking the temperature of the comparator as it may provide an inaccurate reading.
Do take the measurements as quickly as possible, to prevent the surface temperature from changing.
Don’t forget that the thermometers require time to acclimatise to a different environment.
Learn more about infrared thermometers:
Today we have the next installment in our three part Infrared Thermometer series. We discussed the uses and limitations of using infrared thermometers; now let’s talk about correctly storing and cleaning your infrared thermometer. How to clean your infrared thermometer Use a damp soft cloth …
Infrared thermometers are fantastic tools for quickly measuring surface temperatures. However they have their limitations, and knowing how to properly use an infrared thermometer is vital. Today we will be discussing emissivity and how this key factor will affect all infrared readings. Keep your eyes …
Our very first Thermapen was launched in 1992, it was and still continues to be a flagship product for Electronic Temperature Instruments Ltd. However the Thermapen has come a long way from our first model, the Thermapen Classic. We now host a variety of Thermapens’, all of which can be used in many different areas of industry. This got us thinking, what ways can a Thermapen be used that we haven’t advertised? So we got researching and have found 5 weird and wonderful ways in which you can use one of our fabulous Thermapens…
Did you know? You can determine the sex of baby turtles by what temperature they are kept at whilst nesting. There are two different types of sex-determining mechanisms in reptiles: genotypic sex determination (GSD) and temperature-dependent sex determination (TSD). Some species of reptile such as the green iguana have X and Y sex chromosomes (like mammals). Other reptiles governed by GSD have a system, similar to one found in birds, with Z and W sex chromosomes.
However, in some species of reptiles such as certain species of turtles their sex determination is actually temperature-dependent. There is a critical period of embryonic development which actually occurs once the egg has been laid, meaning that the environmental temperature at which the eggs are nested, will determine whether they hatch as female or male. For example, in many turtle species, eggs from cooler nests hatch as all males, and eggs from warmer nests hatch as all females.
Therefore by using an infrared thermometer such as our Thermapen® IR to test the temperature of the eggs, you could potentially ensure that your hatchlings are all born as male or female – simply by keeping them at warmer or cooler temperatures.
Did you know? In the world of the paranormal many determine whether there is a spiritual presence in the room by whether there is a cold-spot. Some people believe that ghosts or spiritual presences draw from the heat and energy in a room to manifest, causing a sudden drop in temperature in one particular spot. Of course critics have said that natural environmental changes cause these cold-spots however believers have stated that it is simply not comparable as it is ‘like walking into a freezer on a hot summers day, just in one spot of the room’.
Investigators of the paranormal are well known to carry thermometers for this exact reason. Many will use a thermometer which has a probe used for measuring ambient air temperatures, such as the Thermapen® 3 with air probe. The Thermapen® 3 thermometer will give a precise read-out over the range of -49.9 to 299.9 °C. However they may also use an infrared thermometer to determine surface temperatures, such as the Thermapen ® IR.
Thermapen Professional thermometers
Thermapen IR infrared thermometer with foldaway probe
Did you know? During pregnancy your bath water cannot exceed a certain temperature. It is advised that while carrying a child your bath water should not exceed your own body temperature, this is suggested between 35°C and 38°C, however always check with your midwife for their recommendations and guidelines. When an expectant mother overheats (becomes hyperthermic) it can potentially cause problems to the unborn baby. Raising your body temperature too high can lead to a drop in blood pressure, which carries a risk of reducing the amount of oxygen and nutrients that your baby is able to get.
Using a thermometer will help eliminate the worry of these risks, simply run your bath and keep a Thermapen Professional handy to ensure the temperature stays below 38°C. This Thermapen has an IP rating of IP66/67 which means if you drop it in the bath, it wont damage it! If you like long relaxing baths you can monitor the temperature and top up as and when needed.
Did you know? Frost can affect many plants, and is particularly damaging to tender new growth and blossom in the spring. Frost will usually threaten crops during Autumn to Spring and is caused by cold temperatures. Ground frost occurs when the temperature of the ground falls below freezing point (0ºC), this is also the same for air frost. Plant cells are very easily damaged by frost, and often completely destroyed. The process of repeated freezing and thawing, or even rapid thawing will more often than not lead to destroyed crops altogether. For many farmers and horticulturalists across the world, the threat of frost is very real to their livelihoods.
We would recommend using our Thermapen ® IR, using the infrared to measure the ground surface temperature and the penetration probe to test the soil temperature. You could also use our Thermapen® 3 with air probe to test for air frost.
Did you know? Chemicals that are used for developing film rolls in photography need to be kept at certain temperatures. When developing a roll of film there is a three stage method using a Developing Solution, Stop Bath and Fixing Solution. The Developing Solution must be stored at the correct temperature, it is also good practice for the the other chemicals and rinsing water to be kept at the same temperature. Even a degree difference will alter the consistency of the outcome of your prints. Different film manufacturers will ask for the chemicals to be stored at slightly different temperatures to suit that particular film.
Therefore one key instrument needed in a dark room is a good thermometer – our Thermapen Professional gives an accurate reading in just 3 seconds and has an IP rating of IP66/67, meaning you can clean it properly after each measurement.