APPENDIX 1
A1.0 ATEX dust certification
In addition to ATEX certification permitting
installation in Zone 2 gas atmospheres which is
described in the main section of this instruction
manual, the BA354NE also has ATEX Ex tc
certification, allowing installion in Zone 22
combustible dust atmospheres.
A1.1
Zones and Maximum Surface
Temperature
The Rate Totaliser has been certified as Group II
Category 3D Ex tc IIIC T80ºC Dc IP66 apparatus
with a Ta of –40ºC to +70C. This is dust ignition
protection by enclosure complying with EN60079-31.
When installed as specified in this instruction
manual and complying with the requirements of
EN60079-14 the Rate Totaliser 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 dust in subdivisions:
IIIA
combustible flyings
IIIB
non-conductive dust
IIIC
conductive dust
Be used with dusts having a Minimum Ignition
Temperature of:
Dust cloud
120°C
Dust layer on Rate Totaliser
155
°
C
up to 5mm thick.
*
Dust layer on Rate Totaliser
Refer to
over 5mm thick.
*
EN60079-14
At an ambient temperature between -40 and +70°C
Note:
The specified operating temperature of the
BA354NE is –20 to +70ºC. At temperatures below
–20ºC the instrument will continue to totalise but the
display will not function.
*
Unlikely occurance in Zone 22
A1.2 Installation
All the circuits shown in the main section of this
manual for Rate Totaliser installations in Zone 2
flammable gas atmosheres, may also be used for
Zone 22 combustible dust applications. The Rate
Totaliser should be located where the minimum
amount of dust will accumulate on the enclosure and
the installation should be as specified in this
instruction manuals and comply with the
requirements of EN 60079-14
Electrical installations
design, selection and erection
EN 60079-14, requires that each of the wires
entering the hazardous area should be individually
fused and contain a means of isolation. However, in
practice instrumentation energised by a current
limited power supply that can be switched off is often
considered adequate.
A1.3 Maintenance
Ex tc protection does not permit live maintenance,
but when fitted with an optional intrinsically safe
external keypad the BA354NE Rate Totaliser may
be calibrated in Zone 22 providing the terminal cover
is not removed
.
ENSURE PLANT SAFETY BEFORE
STARTING MAINTENANCE
The Rate Totaliser terminal and control covers
should only be removed and live maintenance
performed when there is little risk of a
combustible dust being present. During
maintenance ensure that dust or water do not
enter the enclosure. Before replacing the
control and terminal covers ensure that the
sealing gaskets are undamaged and free from
dirt and foreign bodies.
Routine inspection of
t
he Rate Totaliser’s
mechanical condition and removal of accumulated
dust from the outside of the enclosure should be
regularly performed and comply with the
recommendations contained in EN60079-17
‘Electrical Installations Inspections and
Maintenance’. The interval between inspections
depends upon environmental conditions. Removal
of flammable dust should be performed with care to
avoid creating a dust cloud.
37
