ABB AquaProbe 2, Installation Manual

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Insertion-Type Electromagnetic Probe Flowmeter
AquaProbe 2 2 Mechanical Installation
6 IM/AP Issue 9
2.2 Location – Flow Conditions
The probe may be installed in one of two positions in the pipe; either on the centre line or at the mean axial
velocity point (1/8 pipe diameter). It may also be traversed across the pipe to determine the velocity profile.
2.2.1 International Standard for Flow Measurement
ISO 7145 '(BS 1042) Measurement of fluid flow in closed conduits' Part 2 'Velocity area methods'
describes methods of calculating volumetric flow from velocity measurements.
Section 2.2: 1982 'Method of measurement of velocity at one point of a conduit of circular cross section'
describes the inference of volumetric flow from measurement of velocity at a single point. Several
conditions must be fulfilled to validate the method, which uses calculations based on empirical data.
Where the validating conditions can be met, the method described in Section 2.2 is the most practical. It is
possible to measure the velocity either on the centre line, which reduces sensitivity to positional errors, or at
the assumed point of mean flow velocity.
Table 2.1 is an extract from ISO 7145 (BS 1042): Section 2.2: 1982 and is reproduced with the permission
of BSI. Complete copies of the standard can be obtained by post from BSI Publications, Linford Wood,
Milton Keynes, MK14 6LE.
Note. Ensure that the sensor is installed in the pipe with the flow direction arrow on the probe case
matching the pipe flow.
Fig. 2.3 Flow Conditions
Note. Where the above ideal conditions cannot be achieved, the flow profile must be tested for
symmetry in order to obtain reliable flow results.
5 Diameters See Table 2.1