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4. Requirements for use in potentially explosive atmospheres
4. Requirements for use in potentially explosive
!
atmospheres
The built-in Reed contacts do not have their own ignition source.
Note
They are 'simple apparatus' in terms of intrinsic safety as defined in
GB
EN 50 020.
When supplied from a tested and certified intrinsically safe circuit
(associated apparatus), these switches may be used in potentially
explosive atmospheres up to category 2 without having to take any
further measures.
Operating Temperature
Ambient (for use in potentially explosive atmospheres): 0 ... +60 °C
Medium:
The permissible medium temperature does not only depend on the
instrument design, but also on the ignition temperature of the
surrounding explosive atmosphere. Both aspects have to be
taken into account.
Attention! With gaseous substances the temperature may increase as a result
of the compression temperature. In such cases the pressure change rate has to
be slowed down resp. the permissible medium temperature has to be reduced.
Permissible medium temperature
Temperature class of
the ambient atmosphere
(ignition temperature)
T 6 ( > 85 °C)
T 5 ( > 100 °C)
all other temperature classes
Alarm contacts
Especially conceived to allow low current circuits to be switched
directly, switch point may be set by means of adjusting screws
from the exterior in a range of 10 ... 100 % of full scale value.
Max. switching voltage: 30 VDC / VAC
Max. load:
Max. strength of current: 0.2 A
Switching hysteresis:
6
WIKA Operating instructions pressure gauges Model 700.0X with 851 per ATEX
Permissible maximum medium
temperature (in the pressure system)
+70 °C
+85 °C
+100 °C
3 W
5 % of full scale value
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