EN
14170746.03 04/2018 EN/DE/FR/ES
WIKA additional information model TR21 (Ex i)6
For applications with transmitters (TR21-x-xTT, TR21-x-xTB) that require group II
instruments (potentially explosive gas atmospheres), the following temperature class
classification and ambient temperature ranges apply:
Table 3
Hazardous gas atmosphere Temperature
class
Ambient
temperature
range (T
a
)
Max. surface temperature
(T
max
) at the sensor or
thermowell tip
ATEX IECEx
II 1G Ex ia IIC T1, T2 T3,
T4, T5, T6 Ga
II 1/2G Ex ia IIC T1, T2, T3,
T4, T5, T6 Ga/Gb
II 2G Ex ia IIC T1, T2, T3,
T4, T5, T6 Gb
T1 ... T4 -40 ... +85 °C T
M
(medium temperature) +
self-heating
For this, the special conditions
must be observed (see chapter
4 “Special conditions for safe
use (X conditions)”).
T5 -40 ... +60 °C
T6 -40 ... +45 °C
For applications requiring instruments of equipment group II (potentially explosive dust
atmospheres), the following surface temperatures and ambient temperature ranges apply:
Table 4
Hazardous dust atmosphere Power P
i
Ambient
temperature
range (T
a
)
Max. surface temperature
(T
max
) at the sensor or
thermowell tip
ATEX IECEx
II 1D Ex ia IIIC T135 °C Da
II 1/2D Ex ia IIIC T135 °C Da/Db
II 2D Ex ia IIIC T135 °C Db
750 mW -40 ... +40 °C T
M
(medium temperature) +
self-heating
For this, the special conditions
must be observed (see chapter
4 “Special conditions for safe
use (X conditions)”).
650 mW -40 ... +70 °C
550 mW -40 ... +85 °C
For applications that require EPL Gb or Db, the instruments designated as “ia” can also be
used in type “ib” measuring circuits, with the same connection parameters.
Thus the entire measuring circuit (including the sensor circuit) is an “ib” circuit. Instruments
that have been operated in a power supply circuit of type “ib” cannot be re-used in a power
supply circuit of type “ia”.
1. Ex marking