WIKA 4 Mode D'emploi page 12

2. Safety
Explosive gas/air, vapour/air and mist/air atmospheres
Required
temperature class
EN
(ignition temperature
of gas or vapour)
T6 (T > 85 °C)
T5 (T > 100 °C)
T4 (T > 135 °C)
T3 (T > 200 °C)
T2 (T > 300 °C)
T1 (T > 450 °C)
Explosive dust/air atmospheres
For dusts, the procedure specified in ISO/IEC 80079-20-2 for determining the
ignition temperature has to be applied. The ignition temperature is determined
separately for dust clouds and dust layers, respectively. For dust layers, the igniti-
on temperature depends on the dust layer thickness per IEC/EN 60079-14.
Ignition temperature
of dust
Dust cloud: T
cloud
Dust layer: T
layer
The permissible maximum medium temperature must not exceed the lowest
determined value, even in case of a malfunction.
Explosive atmosphere consisting of hybrid mixtures
The instruments must not be used in areas in which an atmosphere consisting of
explosive hybrid mixtures (dusts mixed with gases) can occur.
3. Temperature at the installation site
When mounting the instrument it must be ensured that, taking into consideration
the influence of convection and heat radiation, no deviation above or below the
permissible ambient and medium temperatures can occur.
4. Pressurisation
Pressure surges must be avoided at all costs. Open the shut-off valves slowly.
12
Maximum permissible surface temperature of the
instrument (for the end application)
Instruments with
permissible medium
temperature ≤ 100 °C
+65 °C
+80 °C
+100 °C
+100 °C
+100 °C
+100 °C
Maximum permissible surface temperature of the
instrument (for the end application)
< 2/3 T
cloud
< T − 75 K − (reduction depending on the layer thickness)
layer
WIKA operating instructions pressure gauge model 4 per ATEX
Instruments with
permissible medium
temperature > 100 °C
+65 °C
+80 °C
+105 °C
+160 °C
+200 °C
+200 °C