Temperature Class Classification, Ambient Temperatures - WIKA TR25 Mode D'emploi

6. Information on mounting and operation in hazardous areas

6.2 Temperature class classification, ambient temperatures

The permissible ambient temperatures depend on the temperature class, the cases used
and the optionally built-in transmitter and/or digital display.
When a thermometer is connected to a transmitter and/or a digital display, the lowest value
of either the ambient temperature limits or the highest temperature class will apply. The
lower temperature limit is -40 °C; and -50 °C for special designs.
Where there are neither transmitters nor digital displays mounted within the case, there will
also be no additional warming. With a built-in transmitter (optionally with digital display),
heating caused by operating the transmitter or digital display may occur.
For applications without transmitters (digital displays) that require group II instruments
(potentially explosive gas atmospheres), the following temperature class classification and
ambient temperature ranges apply:
Temperature class Ambient temperature range (T
T6 (-50) -40 ... +80 °C
T5 (-50) -40 ... +80 °C
T4, T3 (-50) -40 ... +80 °C
The permissible ambient temperatures and surface temperatures for third-party products
can be seen from the relevant approvals and/or data sheets and must be observed.
Example
For instruments fitted with a transmitter and DIH10 digital indicator, for example, the
following limit for temperature class classification applies:
Temperature class Ambient temperature range (T
T6 -40 ... +60 °C
For applications requiring instruments of equipment group II (potentially explosive dust
atmospheres), the following surface temperatures and ambient temperature ranges apply:
Power P Ambient temperature range (T
i
750 mW (-50) -40 ... +40 °C
650 mW (-50) -40 ... +70 °C
550 mW (-50) -40 ... +80 °C
The permissible ambient temperatures and surface temperatures for third-party products
can be seen from the relevant approvals and/or data sheets and must be observed.
The values in brackets apply to special designs. These probes are manufactured using
special sealing compounds. Moreover, they feature connection heads made of stainless
steel and cable glands for low-temperature ranges.
WIKA operating instructions model TR25 (Ex i)
)
a
)
a
)
a
EN
21