Choosing the right temperature sensor in 3 steps
We take a look at which factors come into play when choosing the right temperature sensor for your application!
The temperature of a surface or an object can be measured by the amount of infrared radiation that the object emits. The warmer the object, the more infrared radiation. The temperature sensor measures the amount of infrared radiation to determine the surface temperature of the object within a defined spot. In the sensor, the measured value of the radiation is converted into a usable measuring unit: degrees Celsius. The suitable sensor can differ per application. In this article, we will discuss the three main criteria in determining the appropriate temperature sensor: the material, measurement scope and environmental influences.
1. Material type
Firstly, it is important to sort out which materials are present in the application. Earlier, we discussed that heat is nothing but infrared radiation. Thus, materials can be divided into reflectives and non-reflectives. Below, follows an explanation of these two characteristics.
Reflective materials
Materials such as metals fall under the reflective materials. This means these can reflect the heat of other objects as well. A normal temperature sensor, also known as a pyrometer, registers the reflected heat as that of the reflective object. The measurement is not accurate because of this. Special temperature sensors are used for these materials. These sensors measure within a shorter spectral range which makes it possible to measure the heat of the object only. This makes the measurement accurate and reliable. i-Tec USB series.
Non-reflective materials
A regular pyrometer is sufficient for non-reflective materials. Think of materials such as paper, cardboard, asphalt, food, plastics, rubber and painted surfaces. The temperature sensors that are used for these materials measure within a long wavelength. This is sufficient for a reliable temperature measurement because the materials barely reflect heat from other sources. i-Tec E series could provide a solution in such applications.
2. The measurement dimensions
A second point of interest in your choice of sensor are the measurement dimensions. These dimensions are: target size and measuring distance. The sensors measure the average temperature of a surface area. This surface, also known as the measuring spot, is dependent on the optic of the sensor. In other words: the optics define the spot size.
For most temperature sensors it is possible to make a choice in type of optic. The desired measuring surface and distance are decisive in the choice of optic.
Within every optic the measuring surface can be determined by the D:S (Distance to Spot Size) ratio.
For example, the i-Tec Cube XSA0.7-2M-10V is a temperature sensor, which can be used with a very small measuring spot.
3. Ambient conditions
Lastly, the ambient conditions are looked at when deciding which sensor to go for. Especially ambient temperature and the presence of obstructive factors like dust and gas. The influence of these is explained further below.
Ambient temperature
In areas at room temperature it is possible to use a regular pyrometer without any from of cooling. For warmer areas there are special high-ambient-temperature models or versions with air or water cooling. An example of such application is one in which the temperature of a hot metal plate has to be determined. In this application the ambient temperature is much higher.
Obstructive factors
There are also applications in which the sensor can be obstructed by ambient conditions like dust, steam, smoke and gas. These can negatively impact the measurement. Special sensors are available for use in areas with a lot of contamination (dust, mud, etc.) or gas and smoke in the air. When the air in an area looks clear to the human eye, there is often no problem present for a regular pyrometer to be used for reliable measurements.
If you have any questions about choosing the right temperature sensor, you can contact one of our experts for more information via info@sensor.nl or via +31 (0) 416-378239.
Which infrared temperature sensor can you choose?
Below is an overview to give an idea about the usability of our various infrared temperature sensors, based on the aforementioned points. Our series of pyrometers are listed in the table, with the material that can be measured, the available spot ratios and the applicability based on external influence factors.
| Series | Application | Spot ratio | Ambient characteristics |
|---|---|---|---|
| i-Tec E series | Adjustable emissivity | 15:1, 2:1, 30:1 and Close Focus | Ambient temperatures from -20 up to 500°C |
| i-Tec USB series | Measurements behind/of glass surfaces, cold metals (<100°C), | 2:1, 15:1, 30:1 and Close Focus | Ambient temperatures from -40 up to 2000°C |
| i-Tec Mini series | Compact for applications with little installation space - various output functions | 2:1, 15:1, 30:1 and Close Focus | Ambient temperatures between -40 and 1000°C |
| i-Tec MiniUSB Series | Lab research and R&D | 2:1 or 20:1 | Ambient temperatures between -20 and 1000°C |
| i-Tec Cube series | <240 ms response time (S, F models), <1.6 mm measuring spot (XS model), Glass surfaces at high speeds (G model), Plastic foils (P model), Cold metals at high speeds (M model) | 0.7 mm at 40 mm, 1.6 mm at 35 mm, 12 mm at 200 mm, 20 mm at 500 mm, 3 mm at 70 mm, 3.5 mm at 100 mm, 3.5 mm at 200 mm, 4.5 mm at 300 mm, 5.5 mm at 120 mm | Ambient temperatures between 0 and 500°C |
| i-Tec FibreMini Series | Hot airstreams (up to 200°C), High electromagnetic interference (EMI), Alarm functionalities in monitoring | 30:1 or 75:1 | Ambient temperatures from 250 up to 2000°C |
| i-Tec MiniBus Series | Reading out multiple measurements over multiple spots simultaneously | 2:1 and 20:1 | Ambient temperatures from -20 up to 1000°C |
| i-Tec Mini OEM Series | Low-cost and compact temperature measurements | 2:1, 15:1, 30:1 and Close Focus | Ambient temperatures from -20 up to 500°C |
| Calex Pyro NFC | Reading output and configuring parameters wirelessly for low-cost application | 15:1 | Ambient temperatures from 0 up to 1000°C |
| Calex ExTemp | ATEX-compliant temperature measurements | 2:1, 15:1, 30:1 and Close Focus | Environments with explosion hazard (Zone 0 and Zone 20 - ATEX/IECEx) and ambient temperatures from -20 to 1000°C |
| Calex PyroSigma | Precision measurements in applications with very little mounting space | 15:1 | Ambient temperatures from 0 up to 1000°C |
| FLIR AX8 | Non-contact visual temperature inspections with thermography | 80 x 60 pixels | Ambient temperatures from -10 up to 150°C |
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