26
AQUA M A STE R4
|
EL EC T R O M AG N E T I C FLO W M E T ER I N SER T I O N SEN S O R | O I/FE W4 0 0/A P - EN R E V. B
13 Appendix
Declarations of conformity
IMPORTANT (NOTE)
All documentation, declarations of conformity, and
certificates are available in ABB's download area:
www.abb.com/flow
.
Torque information
IMPORTANT (NOTE)
The specified torques are valid only for greased
threads and piping that is not subject to tensile
stress.
Torque values are specific to the flange material
types identified.
Insertion sensor
length
Maximum tightening torque/Nm (ft lbf))
300 (12 in)
40 (30 )
500 (20 in)
40 (30 )
700 (28 in)
40 (30 )
1000 (40 in)
40 (30 )
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, that uses calculations based on empirical data.
Where the validating conditions can be met, the method
described on page 10 is the most practical. It is possible to
measure the velocity either on the center line, which reduces
sensitivity to positional errors, or at the assumed point of mean
flow velocity.
Table 2 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.
IMPORTANT NOTE
Where the above ideal conditions cannot be achieved,
the flow profile must be tested for symmetry in order
to obtain reliable flow results.
Minimum upstream straight
length
*
Type of disturbance
upstream from the
measuring
cross-section
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 Straight pipe lengths –insertion sensor
