5 Installation
25
5.4.8 Installation and grounding in piping with
cathodic corrosion protection
The installation of electromagnetic flowmeters in systems with
cathodic corrosion protection must be made in compliance with
the corresponding system conditions.
The following factors are especially important:
1.
Pipelines inside electrically conductive or insulating.
2.
Pipelines completely or for the most part with cathodic
corrosion protection (CCP) or mixed systems with CCP
areas and PE areas.
• When installing an electromagnetic flowmeter in pipes
with insulating inner lining and free from foreign matter, it
should be insulated with grounding rings on the upstream
and downstream side. The corrosion protection potential
is diverted. The grounding rings upstream and
downstream of the electromagnetic flowmeter are
connected to functional earth (Figure 29 / Figure 30).
• If the occurrence of external stray currents is to be
expected in pipelines with internal insulation (e.g. in the
case of long pipe sections in the vicinity of power supply
units), an uninsulated pipe of approx. 1/4 x DN of length
should be provided upstream and downstream of the
flowmeter sensor in order to deviate these currents away
from the measuring system (Figure 31).
Internally insulated pipelines with cathodic
corrosion protection potential
1
Pipe flange
2
Insulating plate
3
Gasket / insulating ring
4
Grounding plate
5
Insulating pipe
6
Flange
7
Lining
8
Insulation
9
Flowmeter sensor
Figure 29:
Bolt screw view
Install grounding rings on each side of the flowmeter sensor.
Insulate the grounding rings from the pipe flanges and connect
them to the flowmeter sensor and to functional earth. Insulate the
screw bolts for the flange connections when mounting. The
insulation plates and the insulation pipe are not included in the
delivery. They must be provided onsite by the customer.
A
Connecting line for corrosion
protection potential*
B
Insulated screw bolts without
grounding rings
1
Insulated pipe
2
Functional earth
3
Grounding plate
*
≥
4 mm
2
Cu, not included in the delivery, to be provided onsite.
Figure 30:
Flowmeter sensor with grounding plate and functional earth
The corrosion protection potential must be diverted through a
connecting line
A
away from the insulated flowmeter sensor.
Summary of Contents for 406060
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