An infrared thermometer uses a built-in laser to detect the temperature of an object that is out os reach or at a distance, for example an HVAC system. There are many choices in the market and the price varies greatly.
The question is what really matter in choosing the infrared thermometer for your application. Here are some factors that you would consider before making the decision to buy :
1. Determine the field of view (target size and distance)
2. Consider the type of surface being measured and its emissivity
3. Analyze the spectral response for atmospheric effects or transmission through surfaces
4. Specify the temperature range and the mounting needs
5. Don't forget: response time, environment, mounting limitations, viewing port or window applications, and desired signal processing
In order to make an accurate measurement, the below 2 points must be performed correctly.
1. Field of view
The field of view is the angle of vision at which the instrument operates, and is determined by the optics of the unit. To obtain an accurate temperature reading, the target being measured should completely fill the field of view of the instrument. Since the infrared device determines the average temperature of all surfaces within the field of view, if the background temperature is different from the object temperature, a measurement error can occur.
You will often find in the specification of Infrared Thermometer the terms “Optics” or "distance-to-spot" (D:S) ratio, for example, if your thermometer has an optics of 10:1, it measures an approximately one-inch-diameter spot when it's 10 inches from the target. (for example testo 830-T1 comes with 10:1 optics)
The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation, not all materials emit the same amount of infrared energy when they are at the same temperature. Emissivity is expressed as a number between 0 and 1, with 0 being non-emissive and 1 being perfectly emissive.
Emissivity measurements for many surfaces are compiled in many handbooks and texts. Some of these are listed in the following table. Shinier surface has lower emissivity.
If you need to take temperature readings on low emissivity objects regularly, consider an IR thermometer that enables you to compensate for variations in emissivity, eg an infrared thermometer that enables you to set emissivity to "High" (for measuring most surfaces, such as wood, paint, rubber, plaster, or concrete), "Medium" (for oxidized metals or granite, for example), or "Low" (for shiny metals). (For example testo 830-T1 has adjustable emissivity from 0.1 to 1.0)
Now that you have learnt the selection criteria on Infrared Thermometer, let's choose one from our wide selection of Infrared Thermometer