User Manual

RH401 V1.4 09/04

IR Emissivity Adjustment

Emissivity is adjustable from 0.3 to 0.99. The default value is 0.95 which is the typical

emissivity value of many non-metallic surfaces. If the surface to be measured is highly

reflective and the emissivity is not known, cover the surface with paint or tape to improve

measurement accuracy. If the emissivity of the surface is known, follow this procedure to

set the value.

1. With the meter on, Press the key twice to enter the Emissivity setting

procedure. will flash on the top left side of the display.

2. Use the up key and the down key to adjust the value.

3. When the desired setting appears in the display, press again to save and return

back to normal operation.

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 Lather 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

Spot to Distance Ratio

The 8:1 spot to distance ratio determines the size of the measured surface area with

respect to the distance the meter is held away from the surface.