Extech Instruments 42580 Guide de l'utilisateur télécharger pdf (Page 13)

42582-EN v6.1 07/13

Emissivity Considerations

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. The 42580 senses IR energy and calculates the temperature based upon the amount of

IR energy it receives using a factory default emissivity setting of 0.95 (this setting covers 90% of

applications).

Most organic materials and painted or oxidized surfaces have an emissivity factor of 0.95.

Inaccurate readings will result from measuring shiny or polished metal surfaces which have

emissivity factors other than 0.95. To compensate for polished/shiny surfaces, cover the surface

with masking tape or flat black paint. Allow time, before measuring, for the tape to reach the same

temperature as the material underneath it.

Emissivity Factors for Common Materials

Material under test Emissivity Material under test Emissivity

Asphalt 0.90 to 0.98 Cloth (black) 0.98

Concrete 0.94 Skin (human) 0.98

Cement 0.96 Leather 0.75 to 0.80

Sand 0.90 Charcoal (powder) 0.96

Soil 0.92 to 0.96 Lacquer 0.80 to 0.95

Water 0.92 to 0.96 Lacquer (matt) 0.97

Ice 0.96 to 0.98 Rubber (black) 0.94

Snow 0.83 Plastic 0.85 to 0.95

Glass 0.90 to 0.95 Timber 0.90

Ceramic 0.90 to 0.94 Paper 0.70 to 0.94

Marble 0.94 Chromium Oxides 0.81

Plaster 0.80 to 0.90 Copper Oxides 0.78

Mortar 0.89 to 0.91 Iron Oxides 0.78 to 0.82

Brick 0.93 to 0.96 Textiles 0.90

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Extech Instruments 42580 Guide de l'utilisateur Page 13