17
FEM610 |
PROCESSMASTER | OI/FEM610-EN REV. A
5 . . .Installation
G11050
3
10
6
6
1
2
45
8
7
6
9
2
3
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.
. . .Grounding the flowmeter sensor
Installation and grounding in pipelines 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 (Fig. 23 / Fig. 24).
• 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 (Fig. 25).
Internally insulated pipelines with cathodic corrosion
protection potential
Pipe flange
Insulating plate
Gasket / insulating ring
Grounding plate
Insulating pipe
Flange
Lining
Insulation
Flowmeter sensor
1
2
3
4
5
6
7
8
9
Figure 23 Bolt screw view
The corrosion protection potential must be diverted through
a connecting line
A
away from the insulated installed sensor.
G11049
1
1
2
A
B
3
B
B
B
Connecting line for corrosion protection potential
1
)
Insulated screw bolts without grounding rings
Insulated pipe
Functional earth
Grounding plate
* ≥ 4 mm2
Cu, not included in the delivery, to be provided on-site
A
B
1
2
3
Figure 24 Flowmeter sensor with grounding
plate and functional earth
Mixed system pipeline with cathodic corrosion protec-
tion and functional earth potentials
This mixed system has an insulated pipeline with corrosion
protection potential and an uninsulated bar metal pipe (L =
1/4 x flowmeter sensor size) with functional earth potential
upstream and downstream of the flowmeter sensor.
The Fig. 25 shows the preferred installation for cathodic
corrosion protection systems.
G11048
1
2
1
A
2
3
B
B
B
B
Connecting line for corrosion protection potential
1
)
Insulated screw bolts without grounding rings
Insulated pipe
Bare metal pipe
Functional earth
* ≥ 4 mm2
Cu, not included in the delivery, to be provided on-site
A
B
1
2
3
Figure 25 Flowmeter sensor with functional earth
