WIKA TR25 Betriebsanleitung Seite 18

7. Information on mounting and operation in hazardous areas
For applications requiring instruments of equipment Group II (potentially explosive dust
atmospheres), the following surface temperatures and ambient temperature ranges apply:
Table 2
EN
Marking
II 1D Ex ia IIIC T65 °C Da
II 1/2D Ex ib IIIC T65 °C Da/Db
II 1D Ex ia IIIC T95 °C Da
II 1/2D Ex ib IIIC T95 °C Da/Db
II 1D Ex ia IIIC T125 °C Da
II 1/2D Ex ib IIIC T125 °C Da/Db
1) The values in brackets apply to special designs. These sensors are manufactured using special sealing
compounds. Moreover, they feature housings made of stainless steel and cable glands for low-
temperature ranges.
When there is a built-in transmitter and/or a digital display, the special conditions from the
type examination certificate (see item 17) apply.
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
For applications that require EPL Gb or Db, instruments with „ia" marking may also be used
in measuring circuits of type „ib".
7.2 Temperature class classification, ambient temperatures
The permissible ambient temperatures depend on the temperature class, the housings
used and any transmitters and/or digital displays fitted as options.
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 the operation
of the transmitter or digital display may occur.
18
Power Ambient temperature
P range (T
i a
750 mW (-50) -40 ... +40 °C
1)
650 mW (-50) -40 ... +70 °C
1)
550 mW (-50) -40 ... +80 °C
1)
.
4
WIKA operating instructions model TR25 (Ex i)
Max. surface
) temperature (T
at the sensor or
thermowell tip
T (temperature of the
M
medium) + self-heating
For this, the special
conditions (17) must be
observed.
)
max