3. Distance Spot Ratio
The farther the target, the larger the test spot area. This means: As
the distance from thermometer to the object increases, the spot size
of measuring area becomes larger, (as Diagram 1) it is named as
“D:S” (Distance Spot Ratio), for example, if 16:1, the efficient testing
distance should be 16 times as he diameter of the target object.
Make sure the target is larger than the spot size. The smaller the
target, the closer the measuring distance needs to be. When
accuracy is critical, make sure the target is at least twice as large as
the spot size.
4. Emissivity
Most organic materials, painted or oxidized surfaces have an
emissivity of 0.95 (pre-set in the unit). Inaccurate readings will occur
if the surface to be measured is shiny or polished such as stainless
steel or aluminum. To obtain better accuracy, please cover the
surface with masking tape or flat black paint before measuring.
Measure the tape or painted surface when the tape or painted reach
the same temperature of the material underneath. Please kindly
note: thermometer can not measure the temperature of target
objects through the surface of glass. And steam, dust, smog will
lower the accuracy.
3
