WIKA TR25 (Ex i), Operating Instructions Manual

Page: 22 / 128

EN
14073045.06 10/2020 EN/DE/FR/ES
WIKA operating instructions model TR25 (Ex i) 22
According to approval, these thermometers are suitable for the temperature classes
T6 ... T3. This applies for instruments without built-in transmitter and/or digital displays.
Thermometers with transmitters can be used for temperature classes T6 ... T4 and are
marked accordingly. The use of equipment for applications where a lower temperature
class (e.g. T2) than the one marked is required is permitted. Make sure the maximal
ambient temperature for the safe use of the instrument is not exceeded.
6.3 Temperature carry-over from the process
A heat reflux from the process that exceeds the operating temperature of the transmitter
(digital display) or case is not permitted and must be prevented by installing suitable heat
insulation or a respectively long neck tube.
Increasing the distance of the connection components to hot surfaces
The neck length (N) is defined as the distance between the lower edge of the connection
head or case and the heat-emitting surface. The expected temperature at the lower edge
of the connection head or case should be a maximum of 80 °C. The conditions for built-in
transmitters or displays must be considered, and if needed, the neck length should be
increased.
To help select the minimum neck length, the following standard values have been
determined.
Maximum medium temperature Recommendation for
dimension N
Recommendation for
dimension X
100 °C - -
135 °C 20 mm 20 mm
200 °C 50 mm 50 mm
> 200 °C ≤ 450 °C 100 mm 100 mm
WARNING!
For reasons of work safety and saving of resources, hot surfaces should be
protected against accidental touch and energy loss by means of insulation.
6. Information on mounting and operation in hazardous areas