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Insertion-Type Electromagnetic Probe Flowmeter
AquaProbe 2
Type of disturbance upstream from the
measuring cross-section
90° elbow or a t-bend
Several 90° coplanar bends
Several 90° non- coplanar bends
Total angle convergent 18 to 36°
Total angle divergent 14 to 28°
Fully opened butterfly valve
Fully opened plug valve
* Expressed in multiples of the diameter of the conduit.
Downstream from the measurement cross-section, the straight length shall be at least equal to five duct diameters
whatever the type of disturbance.
Table 2.1 Straight Pipe Lengths
2.2.2 Velocity Limitations
All insertion probe devices are susceptible to the vortex shedding effect which can cause severe vibration of
the probe, resulting in damage and/or measurement instability. Electromagnetic devices with no moving
parts, such as AquaProbe, are less susceptible to this effect than mechanical devices.
The graphs below show the maximum permissible velocities, depending on the probe's location.
This information is provided as a guide only. Some installations may experience unwanted vibration
resonance which may further limit the maximum velocity at which the AquaProbe may be used.
8
16
6.0
5.0
4.0
3.0
2.0
1.0
0
0
200 400
Fig. 2.4 Maximum Permissible Velocity for different Pipe Sizes
IM/AP
Issue 9
For a measurement at the
point of mean axial velocity
Pipe Size in inches
24
32
40
48
600 800 1000 1200 1400 1600 1800 2000
Pipe Size in mm
Minimum upstream straight length*
50
50
80
30
55
45
30
56
64
72
80
20.0
17.0
13.0
10.0
7.0
3.0
0
2 Mechanical Installation
For a measurement on the
axis of the conduit
25
25
50
10
25
25
15
Centre Line Method
7
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