Pyle PIRT30 PIRT30 Manual 1 - Page 8

Emissivity and IR Measurement Theory IR Thermometers measure the surface temperature of an object. The thermometer's optics sense emitted, reflected, and transmitted energy. The thermometer's electronics translate the information into a temperature reading which is then displayed on the LCD. The amount of IR energy emitted by an object is proportional to an object's temperature and its ability to emit energy. This ability is known as emissivity and is based upon the material of the object and its surface finish. Emissivity values range from 0.1 for a very reflective object to 1.00 for a flat black finish. For the Model 42515, the emissivity is adjustable from 0.1 to 1.00. Most organic materials and painted or oxidized surfaces have an emissivity factor of 0.95. When in doubt, set the emissivity to 0.95. Emissivity Factors for Common Materials Material under test Asphalt Concrete Cement Sand Soil Water Ice Snow Glass Ceramic Marble Plaster Mortar Brick Emissivity 0.90 to 0.98 0.94 0.96 0.90 0.92 to 0.96 0.92 to 0.96 0.96 to 0.98 0.83 0.90 to 0.95 0.90 to 0.94 0.94 0.80 to 0.90 0.89 to 0.91 0.93 to 0.96 Material under test Cloth (black) Skin (human) Leather Charcoal (powder) Lacquer Lacquer (matt) Rubber (black) Plastic Timber Paper Chromium Oxides Copper Oxides Iron Oxides Textiles Emissivity 0.98 0.98 0.75 to 0.80 0.96 0.80 to 0.95 0.97 0.94 0.85 to 0.95 0.90 0.70 to 0.94 0.81 0.78 0.78 to 0.82 0.90 8