KROHNE DK 46-47-48-800 ATEX II2G Ex i EN - Manual (Page 13)

OPERATION
5
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DK46 - DK800
www.krohne.com 08/2012 - 4000430903 AD DK46/800 II2G R04 en
5.3 Static electricity
Flow-induced static charge
In variable area flowmeters, it is possible under field conditions for charge separation to occur in
the measuring tube due to the transport of non-conductive fluids and/or when the flow comes
into contact with non-conductive internals.
In glass devices, it is basically possible for the electrostatic field generated inside the measuring
tube to "punch through" to the outside of the device.
For that reason, variable area flowmeters need to be permanently grounded by the operator by
way of the process connections in order to allow discharge of electrostatic build-up.
The operator is also responsible for extending the ground continuity of the process pipeline. If
grounding cannot be made via the process connections, e.g. top and bottom connection blocks
are made of plastic, the flowmeter should be connected to the local ground potential via the
connection to ground. This connection only ensures electrostatic grounding of the device and
does not meet the requirements for equipotential bonding.
When dust-free gases or liquids are measured, the flow rate should not exceed 20 times the
nominal flow rate. The max. allowable working pressure PS printed on the type nameplate is to
be noted.
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