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APPENDIX 1
ATEX dust
certification
A1.0 ATEX dust certification
In addition to ATEX Ex nA certification permitting
installation in explosive gas atmospheres which is
described in the main section of this instruction
manual, the BA474ND may also be installed in
combustible dust atmospheres. The transmitter has
Ex nA (non sparking) approval and the enclosure has
Ex tD (protection by enclosure) approved which
satisfy the requirements for Group II Category 3D
apparatus.
A1.1 Zones and Maximum Surface
Temperature
When installed as specified by EN 61241-14
‘Electrical apparatus for use in presence of
combustible dust – selection and installation’, the
Indicating Temperature Transmitter and sensor may
be installed in:
Zone 22 explosive atmosphere in the
form of a cloud of
combustible dust in air is not
likely to occur in normal
operation, but if it does
occur, will only persist for a
short period.
Be used with dusts having a Minimum Ignition
Temperature of:
Dust cloud
120
o
C
Dust layer on BA474ND 155
o
C
up to 5mm thick
Dust layer on BA474ND Refer to
over 5mm thick.
EN 61241-14
At an ambient temperature between -20 and +60
o
C
1.3 Sensor input – terminals 1, 2, 3 & 4
In addition to the Ex nA and Ex tD dust certification,
the ATEX certificate also states that the BA474ND
Indicating Temperature Transmitter sensor input
input, terminals 1, 2, 3 & 4, is galvanically isolated
and intrinsically safe Ex [iaD]. When the transmitter
is installed in a Zone 22 dust hazardous area this
allows the transmitter sensor input, terminals 1, 2, 3
& 4, to be directly connected, without the need for
Zener barriers or galvanic isolators, to a floating or
earthed sensor installed in:
Zone 20
explosive atmosphere in the form
of a cloud of combustible dust in
air is continuously present, or for
long periods or frequently.
Zone 21
explosive atmosphere in the form
of a cloud of combustible dust in
air is likely to occur occasionally in
normal operation.
Thermocouples, resistance thermometers and
potentiometers comply with the requirements for
simple apparatus.
i.e. generate less than 1.5V;
100mA or 25mW and may be connected to the
transmitter input without a safety analysis. Active
devices, such as a voltage source, may also be
connected providing safety is assessed using the
entity concept.
The intrinsic safety parameters for terminals 1, 2, 3 &
4 are:
Uo
=
6.0V
Io
=
30.3mA
Po =
46mW
Ui
=
6.0V
Ii
=
100mA
Pi
=
0.194W
Co
=
23.8µF
Lo
=
3mH
A1.4 Installation
In addition to the installation requirements for use in
explosive gas atmospheres specified in section 6 of
this manual, for applications in combustible dust
atmospheres the BA474ND transmitter must be fitted
with Ex tD certified glands, conduit entries or blanking
plugs.
CAUTION
The temporary dust seals fitted for
transit will not maintain the IP66
protection of the BA474ND enclosure
and are not Ex tD approved.