27
9.4 Pipe mounting kit
The BA393G is a 316 stainless steel kit which will
fix either indicator to a horizontal or vertical pipe
with an outside diameter between 40 and 73mm.
Detailed assembly instructions are supplied with
each BA393G pipe mounting kit.
9.5 Panel mounting kits
Two alternative panel mounting kits are available
for the BA304NG and BA324NG indicators.
The BA394G kit consists of two 316 stainless steel
brackets which secure an indicator into a panel
aperture. The kit does not seal the joint between
the panel and the instrument and it is intended for
mounting an indicator onto an open panel.
The BA494G panel mounting kit is manufactured
from the same carbon loaded GRP material as the
indicator enclosure. It provides an IP66 seal
between the instrument panel and the indicator
and is therefore suitable for mounting a BA304NG
or a BA324NG in a sealed panel enclosure.
However, although the BA494G has ATEX and
IECEx intrinsic safety certification,
the BA494G
does not have formal Ex nA and Ex tc
certification
.
Detailed assembly instructions are supplied with
each panel mounting kit.
9.6
Back-box terminal assembly
If it is necessary to terminate the field wiring prior
to the installation of the indicator display, a back-
box terminal assembly is available as a factory
fitted option. This accessory includes terminals for
the field wiring and diodes which maintain the
continuity of the 4/20mA loop when the indicator
display is unplugged.
When the indicator display is unplugged from the
back-box, the voltage drop introduced into the
4/20mA loop by the instrument increases to 5V. If
an optional backlight is fitted and connected for
loop powering, the voltage drop increases to 11.5V
when the indicator display is unplugged. This
voltage drop can be reduced to 7.5V by connecting
a 7.5V Zener diode with a minimum rating of 1.3W
at 25ºC (BZX85 or 1N5343) between terminals 3
(diode cathode) and 12.(diode anode).
The optional terminal assembly also includes
additional terminals which may be used for linking
cable screens and two terminals connected to the
carbon loaded GRP enclosure. If the enclosure is
not fixed to an earthed structure, one of these
terminals or the earth terminal on the bonding plate
should be connected to the plant's potential
equalising conductor.
Fig 19 Optional back-box terminal assembly
