Test Basis And Safety Information For Intrinsically Safe Control Circuits (Ex-De And Ex-T) - Honeywell FEMA TAM Serie Montage- Und Bedienungsanleitung

7. Test Basis and Safety Information for Intrinsically Safe Control Circuits (Ex-de and Ex-t)

7. Test Basis and Safety
Information for Intrinsically
Safe Control Circuits (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 compart-
MU2B-0375GE51 R0220D
ment features Ex-e Increased 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 prevented.
Ex-t Protection by Enclosure is based
EN60079-0
upon the housing's IP65 rating, which
EN60079-1
EN60079-7 means that it is effectively protected
EN60079-31
against the ingress of dust and water in
accordance with EN60529. Such devices
are thus suitable for use in dusty ex-
plosive 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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