Kapat KARAT-520, Operation Manual

Page: 38 / 52

Figure 2.9 – Diagram of potential equalization
1
Callout. Security jumper between flowmeters. It equalizes potentials between
flowmeters and protects calculator inputs from interferences, which may occur
on the pipeline.
Jumper is connected to the ground screw on flowmeter body.
2
Jumper is made of copper wire with 4-6 mm cross-section.
2
Callout. Security jumper is installed if the flowmeter flanges (or screwed caps)
have insulated coating.
2
Copper wire with 4-6mm cross-section is used for shunting
КАRАТ-520
КАRАТ-520
1
2
2.3.4.5. Flowmeter mounting
It is recommended to obey the following rules during flowmeter instal-
lation :
n
Flowmeter should be installed on the pipeline between SAE ele-
ments (straight pipes and welded flanges) in such a way that arrow
direction on FT body corresponds to flow direction of working fluid in
the pipeline;
n
Sealing gasket should be installed between flowmeter and pipeline
and fastened by screwed cap (in case of thread joint) and mounting
bolt (in case of flange joint);
n
Repeat procedure mentioned above for the second sealing joint of
flowmeter with pipeline;
n
Mounting elements of SAE and flowmeter should be strapped
down; bolts should be tightened on flange joint by turns by diametri-
cally opposite pairs.
It is required to ensure that there is no misalignment of sealing gas-
kets of flowmeter FT during installation.
Displacement of sealing gaskets inside the flowmeter FT is not al-
lowed.
2.3.5. Electric installation work
Electrical circuits should be connected after welding and mounting
works completion in accordance with connection diagrams given in
1.4.3 clause of the present manual.
It is not allowed to place lines of flowmeter communication with exter-
nal devices next to power cables. Cables of communication lines
should be routed in protective crinkled hose.
Ohmic resistance of communication line should be less than 40 Ohm,
capacity — less than 1000 pF, inductance — less than 1 mH.
In order to eliminate foreign potentials and interferences and to pro-
tect calculator inputs it is recommended to organize potential equal-
ization as it is mentioned on figure 2.9.
calculator
Flowmeter is connected to external power source by means of cable
with the length not more than 50 meters and wires cross-section not
2
less than 0.3 mm , and by cable with the length not more than 100 m
2
and wires cross-section not less than 0.6 mm .
СМАФ.407251.002 РЭ – Operations manual Edition 3.0. August 2012
38
КАRАТ-520 Ultrasonic flowmeters
КАRАТ RPA www.karat-npo.ru