Dismantling, Flange systems, Replacement of the signal converter – KROHNE BM 70A EEx EN User Manual
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07/2010 - 4000662402 MA BM70x-Ex-AD-R02-en
8.2. Flange systems
The flange systems do not require any maintenance under normal operating conditions and when
‘used as prescribed’. Depending on application, however, in unfavourable operating conditions the
measuring function may be impaired by contamination of the antenna system. The antenna should
then be cleaned as described in the Installation and Operating Instructions for non-hazardus-duty
versions. Cleaning requires that the flange system be dismantled. This dismantling will need to be
coordinated with field conditions (e.g. check for the existence of a flammable liquid or explosive
atmosphere in or at the tank, pressurized tanks) and is the responsibility of the operator.
9. Dismantling
9.1. Replacement of the signal converter
The modular design of the BM 70..-Ex and BM 700-Ex devices allows replacement of the signal
converter to be carried out by undoing screws M as shown in the diagram on the next page. The
flange system need not be removed from the tank. This applies to pressurized tanks as well.
Caution:
On pressurized tanks, do not remove the 4 screws (H)
connecting the waveguide window to the tank mounting flange.
DANGER TO LIFE!
Before disconnecting the device interconnecting cables, make sure that all cables leading into the
signal converter are isolated from ground (reference potential) of the hazardous location. This also
applies to safety conductors (PE) and equipotential bonding conductors (PA). Exception: intrinsically
safeoperated converter of type BM 702-Ex / BM 702 A-Ex.
Should it prove necessary to open the flameproof enclosure of the electronics compartment in the
presence of an explosive atmosphere, first make sure that the device is disconnected from the supply.
Before opening the flameproof enclosure, be absolutely sure to allow the waiting time, specified on the
nameplate of the signal converter (22 minutes for BM 70..-Ex and 10 minutes for BM 700-Ex), to
elapse first.
Distance piece
(for high-temperature
version up to 250°C)
upper Teflon plug
O-ring
lower Teflon plug
O-ring
BM70
connecting flange
signal converter
Antenna extension
Antenna
M
H
Assembly bolts for signal converter (M)