Instructions

G 1200 series Measurement Basics | 5
B-H89.0.0X.DK2-1.0 11 / 18
5 Measurement Basics
5.1 Sensor/device accuracy
The device can be equipped with different interchangeable sensors. The temperature
sensors are divided into the following classes according to EN 60584-2.
class
deviation
temperature range
1
±1.5 °C or ±0.4 % of measured value *
-40 … 1000 °C
2
±2.5 °C or ±0.75 % of measured value *
-40 … 1200 °C
3
±2.5 °C or ±1.5 % of measured value *
-200 … 40 °C
* = larger value counts
The system accuracy of the measuring chain (device + probe) is the sum of the accu-
racy of the probe and the accuracy of the characteristic curve and cold junction of the
device.
5.2 Possible measuring errors
5.2.1 Immersion depth
_
Liquid: 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 immer-
sion depth is too shallow.
Gas: Immerse as far as possible into the gas to be measured so that the measur-
ing sensor is subjected to a heavy flow.
5.2.2 Surface effects and poor heat transfer
_
Special measuring sensors are required for this purpose. Surface characteristics, de-
sign of the measuring sensor, heat transfer and environmental temperature influence
the measurement result.
NOTE: Thermally conductive paste between the measuring sensor and surface can
also in-crease measurement accuracy in some cases.
5.2.3 Cooling / evaporation
_
When measuring the air temperature, the probe should be dry, otherwise the tempera-
ture measured will be too low.
5.2.4 Response time
_
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.