Velleman DVM8838 - Manual (Page 6)

DVM8838
00 (23/10/2008) 6 Velleman ®
Field of view
The target must be larger than the spot size to ensure correct measurement. This means
that for smaller targets, the thermometer must be held closer to the target. For best
accuracy, make sure the target is at least twice as large as the spot size.
Emissivity
Emissivity describes the energy-emitting characteristics of materials. Most organic or
oxidized surfaces have an emissivity of ±0.95 (default setting). Measuring shiny or polished
surfaces will be inaccurate. Use some masking tape or paint to compensate, allow sufficient
time for the tape or paint to reach the surface temperature.
Substance Emissivity Substance Emissivity
Asphalt 0.90 to 0.98 Cloth (black) 0.98
Concrete 0.94 Human skin 0.98
Cement 0.96 Leather
0.95 to
1.00
Sand 0.90
Charcoal
(powder)
0.96
Earth 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
8. Troubleshooting
LCD display doesn’t light up when the
measurements trigger is pulled. Possibly a battery problem. Check and
replace the battery.
The measured temperature changes very
quickly and the shown value seems unlikely. Check the emissivity value. When set too
low, inaccurate readings will result.
• Repairs or service should only be carried out by qualified and trained technicians.
9.
Cleaning and storage
• The IR sensor (1) is the most delicate part of the thermometer and should be kept clean
at all times. To do this, only use a soft cloth or cotton bud. Do not use excessive
pressure on the sensor.