WIKA TR25 - Handbuch (Seite 17)

WIKA operating instructions model TR25 (Ex i)
14073045.01 10/2013 GB/D
17
GB
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, 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.
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 (Ta)
T6 (-50) -40 … +80 °C
T5 (-50) -40 … +95 °C
T4, T3 (-50) -40 … +100 °C
See and observe the permissible ambient temperatures and surface temperatures for third-party
products from the relevant approvals and/or data sheets.
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 (Ta)
T6 -40 … +60 °C
For applications that require Group II instruments (potentially explosive dust atmospheres), the
following surface temperatures and ambient temperature ranges apply:
Power Pi
Ambient temperature range (Ta)
750 mW (-50) -40 … +40 °C
650 mW (-50) -40 … +70 °C
550 mW (-50) -40 … +100 °C
See and observe the permissible ambient temperatures and surface temperatures for third-party
products from the relevant approvals and/or data sheets.
7. Information on mounting and operation in hazardous areas