Testing Principles And Safety Information For Ex-De And Ex-T - Honeywell Fema DCM-203-574 Series Assembly And Operating Instructions Manual

8. Testing Principles and
Safety Information for Ex-
de and Ex-t
General
Ex-d Pressure-Proof Housing:
Ex-e Increased Safety:
Ex-t Protection by Enclosure:
Ex-d Pressure-Proof Housing is based on
equipping the device with a microswitch
certified according to Ex-d. A spark which
might possible form when the micro-
switch's contact is opened then has no
effect upon any flammable atmosphere
surrounding the switch. As a result of the
defined ignition gap and designed leak-
tightness, any spark-formation is effectively
suppressed in the microswitch, so that a
flammable atmosphere (the frequency of
which is defined in zones 1, 2, 21, and 22)
surrounding the switching device cannot
be ignited.
Furthermore, the housing in the connection
compartment features Ex-e Increased
MU2B-0238GE51 R0616D
8.

Testing Principles and Safety Information for Ex-de and Ex-t

Safety. Through the use of a suitable
earthing, a certified power terminal, and a
certified cable gland, ignitions in the leak-
tight connection compartment are
EN60079-0 prevented.
EN60079-1
Ex-t Protection by Enclosure is based upon
EN60079-7
the housing's IP65 rating, which means
EN60079-31
that it is effectively protected against the
ingress of dust and water in accordance
with EN60529. Such devices are thus
suitable for use in dusty explosive
surroundings (the frequency of which is
defined in zones 1, 2, 21, and 22).
Generally speaking, pressure switches
featuring Ex-de and Ex-t are employed on
the switching device side, in zones 1 and 2
(gas) as well as 21 and 22 (dust). In the
case of protection in dusty explosive
surroundings, the sensors are certified for
use on the medium-side in zone 20.
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