Waterworks
IOM
Sensors
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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 Operating principle
In accordance with the international standard ISO 7145 - Determination 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 ~
– – D
1
1
8
Where R is the radius of the passage section and Di the internal diameter of the same.
velocità assiale media
v @ 1/8 Di = average axial speed
y1 ~ 1/8 Di
Fig. 57 Operating principle
