30
A1.5 Maintenence
In addition to the maintenance information for use in
explosive gas atmospheres specified in section 9, for
applications in combustible dusts
ENSURE PLANT SAFETY BEFORE STARTING
MAINTENANCE
Use as a Ex nA Ex tD instrument
Transmitter and sensor in Zone 22
Maintenance may only be performed
when the transmitter loop is not
energised, or there is no risk of a
combustible dust being present.
The BA474ND terminal cover should only
be removed when dust and water can not
enter the enclosure. Before replacing the
terminal cover ensure that the sealing
gasket is undamaged and that it is free
from foreign bodies.
Use as a Ex nA Ex tD instrument with an
intrinsically safe Ex [ia] sensor input
Transmitter in Zone 22, sensor in Zone 20 or 21
Maintenance may only be performed on
the transmitter and the 4/20mA output
loop when it is not energised, or there is
no risk of a flammable atmosphere being
present.
The BA474ND terminal cover should only
be removed when dust and water can not
enter the enclosure. Before replacing the
terminal cover ensure that the sealing
gasket is undamaged and that it is free
from foreign bodies.
The transmitter input terminals, the
sensor and the wiring between them are
intrinsically safe. Live maintenance is
permitted but only certified test
equipment may be used unless there is
no risk of an explosive atmosphere being
present.