WIKA TC12-M - Handbuch (Seite 26)

GB
7. Information on mounting and operation in hazardous areas
14083458.01 09/2013 GB/D
WIKA operating instructions models TR12, TC12 (Ex i) 26
Use in methane atmospheres
Owing to the higher minimum ignition energy of methane, the instruments can also be
used where methane causes a potentially explosive atmosphere. The instrument can be
optionally marked with IIC + CH
4
.
For applications that require EPL Gb or Db, the instruments marked with “ia” can also be
used in type “ib” measuring circuits.
7.2 Temperature Class classification, ambient temperatures
The permissible ambient temperatures depend on the temperature class, the housings
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 housing, 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
a
)
T6 (-50) -40 … +80 °C
T5 (-50) -40 … +95 °C
T4, T3 (-50) -40 … +100 °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 DIH10 transmitter and digital display, for example, the following
limit for temperature class classification applies:
Temperature class Ambient temperature range (T
a
)
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 Pi
Ambient temperature range (T
a
)
750 mW (-50) -40 … +40 °C
650 mW (-50) -40 … +70 °C
550 mW (-50) -40 … +100 °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.