TD22
Bases for measurement | 7
B-H86.0.0D.DB201-1.0
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7 Bases for measurement
7.1 Possible measuring errors
7.1.1 Immersion depth
Liquids
Immerse to a depth of at least 20 mm and then stir. Otherwise, measuring errors can
occur due to the heat transmission of the sensor tube if the immersion depth is too
shallow.
Gases
Immerse as far as possible into the gas to be measured so that the measuring sensor
is subjected to a heavy flow.
7.1.2 Surface effects and poor heat transfer
Surface temperature
Special measuring sensors are required for this purpose. Surface characteristics,
design of the measuring sensor, heat transfer and environmental temperature influ-
ence the measurement result.
NOTE
Thermally conductive paste between the measuring sensor and surface can also in-
crease measurement accuracy in some cases.
7.1.3 Cooling / evaporation
Air temperature
The measuring sensor should be dry; otherwise the temperature measurement is too
low.
7.1.4 Response time
Response time T
90
An adequate wait time must be observed for the measuring process before reading
the measured value. The response time T
90
describes the time in which the displayed
measured value reached 90% of the end value. See
7.1.5 Limit values
Temperature range
CAUTION
Destruction of the measuring sensor!
When conducting measurements in media with high or very low temperatures, there is
a risk that the measuring sensor is not designed for such extremes.
– The limit values must be observed!