ABB AquaProbe 2, Руководство по установке

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Insertion-Type Electromagnetic Probe Flowmeter
AquaProbe 2 2 Mechanical Installation
IM/AP Issue 9 7
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.
Type of disturbance upstream from the
measuring cross-section
Minimum upstream straight length*
For a measurement at the
point of mean axial velocity
For a measurement on the
axis of the conduit
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
50
50
80
30
55
45
30
25
25
50
10
25
25
15
* 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
Fig. 2.4 Maximum Permissible Velocity for different Pipe Sizes
Pipe Size in inches
Maximum V
elocity in m/s
Pipe Size in mm
Maximum V
elocity in ft/s
0
3.0
7.0
0
200 400 600 800 1000 1200 1400 1600 1800 2000
0
1.0
2.0
3.0
4.0
5.0
6.0
8 16 24 32 40 48 56 64 72 80
10.0
13.0
17.0
20.0
Centre Line Method