8
12. Notes on Measurement
⚫
Measurement Spot Size
The measurement spot size of this thermometer changes in accordance with the distance as shown below.
The diameter of the measuring spot shown above is defined on the basis of the area that receives 90% or
more of the energy. The D:S ratio, which is the ratio of the distance between the object and the thermometer
to the size of the spot, is preset at 6:1 (D = measuring distance, S = diameter of spot). For example, for the
distance of 150 mm, a spot circle of diameter 25 mm can be measured. If the object is too small, make the
distance smaller by bringing the thermometer closer to the object. For higher accuracy, make sure that the
area of the object is at least twice as large as the spot being measured.
Note
: If the area of the object is much larger than the spot size, the
accuracy of measurement is affected. Also, if the area of the
object is much smaller than the spot size, the accuracy of
measurement may be affected by inclusion of a part that is
not supposed to be measured.
⚫
High-temperature Measurement
1. Operating the thermometer continuously to measure a high-temperature (200°C or more) object at a
short distance (30 mm or less) for a long time (three minutes or more) may cause a drop in the
performance of the infrared lens. When measuring a hot object of 200°C or more, the distance should
be 30 mm or more and operation should be completed within a short time.
2. There is also the risk of burning your hand by accidental contact with an excessively hot object. Secure
a safe distance from the object if the object is known to be hot.
⚫
Low-temperature measurement
The ambient operating temperature range of the PC-8400
Ⅱ
is 0 to 50°C. Never use this thermometer in a
freezer of 0°C or colder. When used in a refrigerator of 0°C or warmer, erratic readings may be displayed
until the thermometer has adapted to the ambient temperature inside the refrigerator. When the PC-8400
Ⅱ
is moved to an atmosphere at least 10°C higher or lower than where it was moved from, allow the
thermometer to adapt to the new ambient temperature for at least 30 minutes before starting measurement.
⚫
Measurement of an object having an emissivity other than 0.95
Set emissivity to 0.95 and apply heat-resistant paint or tape that has an emissivity close to 0.95 to the object
to be measured.
D
Distance
S
Diameter
