The emissivity of a material (usually written ε or e) is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. A true black body would have an ε = 1 while any real object would have ε < 1. Emissivity is a dimensionless quantity.
Generally, the duller and blacker a material is, the closer its emissivity is to 1. The more reflective a material is, the lower its emissivity. Highly polished silver has an emissivity of about 0.02.
Examples of emissivity values applicable for material temperatures from 0 to 250°C
0.10 – 0.05
Aluminum Oxide 0.40 Ceramic 0.90 – 0.95 Foods 0.85 – 1.00 Paper 0.85 – 1.00
Steel Cold Rolled
0.70 – 0.90
0.10 – 0.40
Asbestos 0.95 Concrete 0.95 Gravel 0.90 – 0.95 Plastic 0.95 – 1.00 Steel Rough surface 0.95
0.10 – 0.30
Asphalt 0.90 – 1.00 Chromium 0.10 Gypsum 0.85 – 0.95 Steel Unoxidized 0.10 Carpet 0.85 – 1.00
0.60 – 0.95
Graphite 0.70 – 0.80 Electrical terminal blocks 0.60 Human Skin 0.99 Steel Oxidized 0.70 - 0.95
In many production and processing facilities, operations take place at high temperatures. Proper automation and quality control require safe detection and monitoring of temperatures without contact.
Infrared heat sensors absorb the heat radiation of objects and convert it into a switching signal. The advantage of having no mechanical contact between the object and the sensor makes infrared sensors idal for temperature monitoring applications, such as moving objects in spaces with difficult access, conductive or sticky objects/materials, surface treated objects, or on aggressive media where short responce times are required, dangerous applications for direct contact. Our range includes stand alone sensors & systems that can monitor temperature from a distance within the range of -20ºC to 2500ºC.