Infrared Temperature Sensors Technical Specifications
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A noncontact infrared sensor is a device that measures the energy radiated from an object, without touching it. This allows for quick and safe measurement of the temperature of objects that are moving, extremely hot, or difficult to reach. Sensors can be added to a process in a fixed fashion or can be used as handheld devices for quick, on the fly measurements.
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- Infrared Sensors - Overview of Infrared
- Infrared Sensors - Infrared Radiation
- Infrared Sensors - Emissivity Information
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Why Use Infrared Measurement?
- It is fast - time saved, allowing for more measurements and accumulation of data.
- It facilitates measurement of moving targets.
- Measurements can be taken of hazardous or physically inaccessible objects.
- Measurements of high temperatures (greater than 1300°C) present no problems. In similar cases, contact thermometers cannot be used, or have a limited life.
- There is no interference - no energy is lost from the target. For example, in the case of a poor heat conductor such as plastic or wood, measurements are extremely accurate with no distortion of measured values, as compared to measurements with contact thermometers.
- There is no risk of contamination and no mechanical effect on the surface of the object; thus wear-free. Lacquered surfaces, for example, are not scratched and soft surfaces can also be measured.
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What to Keep in Mind When Using Infrared:
- The target must be optically (infrared-optically) visible to the IR sensor. High levels of dust or smoke make measurement less accurate. Concrete obstacles, such as a closed metallic reaction vessel, allow for only topical measurement - the inside of the container cannot be measured.
- The optics of the sensor must be protected from dust and condensing liquids.
- Normally, only surface temperatures can be measured, with the differing emissivities of different material surfaces taken into account.
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Infrared Wavelength
 Infrared Radiation on the Electromagnetic Spectrum
Every form of matter with a temperature above absolute zero emits infrared radiation. The cause of this is the internal mechanical movement of molecules. The intensity of this movement depends on the temperature of the objects. The spectrum of this radiation ranges from 0.7 to 1000 µm wavelength. For this reason, this radiation cannot normally be seen by the naked eye. This area lies within the red area of visible light and has therefore been called "infra"-red.
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Emissivity of Most Common Materials
Emissivity is the measure of an object's ability to emit infrared energy. Emitted energy indicates the temperature of the object. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody). Most organic, painted or oxidized surfaces have emissivity values close to 0.95. Most of our infrared sensors have adjustable emissivity to ensure accuracy when measuring other materials such as shiny metals.
If you are using an infrared sensor with a fixed, preset emissivity of 0.95, and need to measure a shiny object you can compensate by covering the surface to be measured with spray oil, flat black paint or masking tape. Please note that these tables are only to be used as a guide as emissivity changes with temperature and surface finish. |
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Emissivity Table for Non-Metals (Spectral Response: 8-14 µm)
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Material |
Emissivity |
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Asbestos |
0.95 |
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Asphalt |
0.95 |
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Basalt |
0.7 |
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Carbon |
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Unoxidized |
0.8-0.9 |
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Graphite |
0.7-0.8 |
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Carborundum |
0.9 |
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Ceramic |
0.95 |
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Clay |
0.95 |
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Concrete |
0.95 |
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Cloth |
0.95 |
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Glass |
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Plate |
0.85 |
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Gob |
n.r. |
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Gravel |
0.95 |
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Gypsum |
0.8-0.95 |
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Ice |
0.98 |
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Limestone |
0.98 |
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Paint (non-Al.) |
0.95 |
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Paper (any color) |
0.95 |
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Opaque Plastic |
0.95 |
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Rubber |
0.95 |
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Sand |
0.9 |
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Snow |
0.9 |
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Water |
0.93 |
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Emissivity Table for Metals (Spectral Response: 8-14 µm)
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Material |
Emissivity |
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Aluminum |
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Unoxidized |
n.r. |
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Oxidized |
0.2-0.4 |
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Alloy A3003 |
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Oxidized |
0.3 |
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Roughened |
0.1-0.3 |
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Polished |
n.r. |
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Brass |
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Polished |
n.r. |
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Burnished |
0.3 |
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Oxidized |
0.5 |
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Chromium |
n.r. |
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Copper |
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Polished |
n.r. |
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Roughened |
n.r. |
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Oxidized |
0.4-0.8 |
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Electrical Terminal Blocks |
0.6 |
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Gold |
n.r. |
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Haynes Alloy |
0.3-0.8 |
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Inconel |
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Oxidized |
0.7-.95 |
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Sandblasted |
0.3-0.6 |
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Electoropolished |
0.15 |
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Iron |
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Oxidized |
0.5-0.9 |
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Unoxidized |
n.r. |
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Rusted |
0.5-0.7 |
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Molten |
n.r |
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Iron, Cast |
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Oxidized |
0.6-0.95 |
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Unoxidized |
0.2 |
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Molten |
0.2-0.3 |
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Iron, Wrought |
0.9 |
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Lead |
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Polished |
n.r. |
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Rough |
0.4 |
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Oxidized |
0.2-0.6 |
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Magnesium |
n.r. |
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Mercury |
n.r. |
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Oxidized Molybdenum |
0.2-0.6 |
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Nickel |
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Oxidized |
0.2-0.5 |
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Electrolytic |
n.r. |
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Platinum |
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Black |
0.9 |
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Silver |
n.r. |
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Steel |
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Cold-Rolled |
0.7-0.9 |
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Ground Sheet |
0.4-0.6 |
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Polished Sheet |
.1 |
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Molten |
n.r. |
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Oxidized |
0.7-0.9 |
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Stainless |
0.1-0.8 |
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Tin (Unoxidized) |
n.r. |
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Titanium |
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Polished |
n.r. |
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Oxidized |
0.5-0.6 |
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Polished Tungsten |
n.r. |
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Zinc |
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Oxidized |
0.1 |
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Polished |
n.r. |
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*n.r. = Not recommended for 8-14µm sensors. |
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