ADS Environmental Services PrimeProbe2 QR 775016 A0 - Manual (Page 14)

PrimeProbe2 User Manual
10
International Standard of Flow Measurement
The following table has been reproduced, with permission, from ISO 7145
(BS 1042) Section 2.2 1982. Complete copies are available from BSI
Publications, Linford Wood, Milton Keynes, MK14 6LE.
Minimum Upstream Straight Length*
Type of Disturbance
Upstream from the Cross-
Section of Measurement
For Measurement
at the Point of
Mean Axial
Velocity
For Measurement
on the Axis of the
Conduit
90-degree elbow or a t-bend 50 25
Several 90-degree coplanar
bends
50 25
Several 90-degree non-
coplanar bends
80 50
Total angle convergent 18 to
36 degrees
30 10
Total angle convergent 14 to
28 degrees
55 25
Fully-opened butterfly valve 45 25
Fully-opened plug valve 30 15
* Expressed in multiples of the diameter of the conduit.