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Sensors
EUROMAG | SENSORS | Ed. 04/2019
7
INSERTION METERS
7.1
INTRODUCTION
The insertion flowmeters are intended to be inserted inside existing pipes, with minimal intervention on
the existing system, through a threaded or flanged sleeve and possibly a valve.
The meter can be installed in any pipe of internal diameter between DN50 and DN2600.
This type of sensor is designed for use in survey applications, such as leakage monitoring and network
analysis, and in permanent locations where cost or space limitations preclude the use of conventional
flowmeters.
7.1.1 7.1.1 Operating principle
In accordance with the international standard ISO 7145 - D
etermination of flow rate of fluids in closed
conduits of circular cross-section - Method of velocity measurement at one point of the cross-section
,
based on a large number of experimental results it was possible to establish that, in turbulent conditions
and within certain application limits*, the position of the circle centered on the axis of the tube, in which
the local speed is equal to the average axial speed, remains fixed when the flow rate varies and is the
same for any tube:
y
1
= 0,242 * R ≃
1
8 D
i
Where R is the radius of the passage section and D
i
the internal diameter of the same.
v @ 1/8 Di = average axial speed
velocità assiale media
Fig. 57 Operating principle