Infrared thermometers are extremely useful when used in the right way and for the right applications. However, before you can develop confidence in their ability to give fast temperatures, you must understand their limitations.
* In some cases, Infrared Thermometers can be MORE accurate than a surface probe because surface probes have their own temperature and can affect the surface being measured by coming into contact with it.
"Emissivity" is a measure of a material's relative ability to emit radiated energy. It is measured on a scale from just above 0.00 to just below 1.00.
Emissivity depends on factors such as temperature, emission angle, and wavelength. 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. Most organic materials, including the byproducts of plants and animals, have an emissivity rating of 0.95.
Check your infrared thermometer to see if it has adjustable emissivity settings as a feature. Then check your target material against this Emissivity Table.
Infrared thermometers only measure surface temperatures, so they are not very effective at testing if food is properly cooked. Use traditional probe thermometers for this.
If using an infrared thermometer with liquids like soups and sauces, ensure you stir vigorously before taking a measurement to more closely approximate the internal temperature of the liquid. Be aware that steam, even when a liquid is not boiling, can condense on your thermometer and affect the accuracy of your measurements.
An Infrared thermometer will NOT measure temperature accurately through glass, liquids or other transparent surfaces even though visible light (like a laser) passes through them. If you point an infrared thermometer at a subject through a closed window, you will be measuring the surface temperature of the window itself, not the object you are aiming at.
No. As in the answer above and for the same reasons, an infrared thermometer will only measure the surface temperature of water, not the object's temperature.
The "spot size" of any measurement is controlled by two variables:
Usually listed on the thermometer itself, the "distance to target ratio" (DTR) or "spot ratio" tells you the diameter of the "circle" of surface area an infrared thermometer will measure at a given distance.
For example, an infrared thermometer with a 12:1 ratio will measure the temperature of a 1" diameter circle of surface area from 12" away, a 2" diameter circle of surface area from 24" away, and so on.
For accuracy, an infrared thermometer should be kept free of dirt, dust, moisture, fog, smoke and debris. Always take the time to clean your infrared thermometer after exposure to a dirty, dusty, smokey or humid environment. You should also plan a regular cleaning every six months or so. Particular care should be taken to keep the infrared lens or opening clean and free of debris.
To clean your infrared thermometer:
Never submerge any part of the thermometer in water.
That will depend on the model or type of your infrared thermometer. Read the user manual that came with your infrared thermometer to lear about the full range of features it offers and how to use them.
Highly-polished metals typically have very low emissivity ratings, as they tend to be very reflective of ambient infrared energy and less effective at emitting their own electromagnetic waves. If you point an infrared thermometer with fixed emissivity at a stainless steel pot filled with boiling water, you might get a reading closer to 100°F (38°C) than 212°F (100°C). That's because the shiny metal is better at reflecting the ambient radiation of the room than it is at emitting its own infrared radiation.
Some infrared thermometers have fixed emissivity settings of (usually of 0.95 or 0.97) to simplify their operation while leaving them suitable for most material surfaces, including almost all foods.
Other infrared thermometers come with adjustable emissivity settings, so you can more accurately prepare your thermometer for the type of surface being measured, particularly when measuring non-organic surfaces.
Infrared thermometers can be calibrated for accuracy just like other thermometers. In calibration labs like the in-house UKAS certificated ETI Calibration Laboratory at our factory in Worthing, our technicians use industrial black bodies to calibrate infrared thermometers. You can contact them by emailing firstname.lastname@example.org or ask for the calibration lab on 01903 202151
If neither an industrial black body or a comparator cup are available, however, you can do a quick calibration using a properly made ice bath.
RayTemp® 38 infrared non-contact thermometer for measuring small surface areas at greater distancesauto-power off & backlight functions wide temperature range -59.9 to 999.9°C robust housing for durability target distance/diameter ratio of 50:1 RayTemp® 38 is sold excluding probe
RayTemp® 38 infrared non-contact thermometer for measuring small surface areas at greater distancesauto-power off & backlight functions wide temperature range -59.9 to 999.9°C robust housing for durability target distance/diameter ratio of 50:1 RayTemp® 38 is sold excluding probeOut of stock