Badger Meter Vortex Meters - Manual (Page 19)

19 09-VRX-UM-00408 07/12
APPENDIX
ADDITIONAL INSTALLATION REQUIREMENTS
Introduction
Installing a fl ow meter is something which requires careful consideration. It cannot just be placed in a line somewhere and be
expected to fulfi ll its purpose adequately. The geometry and condition of the pipe runs in the area of the installation must be
considered to ensure the best and most accurate operation of the fl ow-meter. This appendix provides suggestions for optimum
installations.
Most flow meter manufacturers define installation conditions in terms of upstream and
downstream straight pipe lengths from the point of installation. Unfortunately this is not the
only requirement, and one needs to consider other peripheral conditions, such as proximity and
style of bends, and other equipment installed in the line. By doing this, problems of turbulence,
swirl, and sonic noise may be avoided.
Turbulence
Turbulence is a disturbance of the fl ow caused by bends and
obstructions in the fl ow stream (it is this phenomenon which
makes the vortex fl ow meter work). Fortunately turbulence dies
out fairly quickly, so by positioning the fl ow meter well away from
bends and obstructions this potential problem of measuring fl ow
in turbulent conditions is overcome (See Figure A1).
Swirl
Unlike turbulence, swirl will not die away. Once created it will
continue until dissipated on the next pipe bend in
the system. Swirl occurs after two bends, in close
proximity, which are at an angle to each other.
When designing an installation, keep the fl ow
meter out of any line which has two adjacent
bends upstream. (See Figure A2).
Sonic Noise
Sonic noise is created by valves (either fl ow control or pressure control valves)
which are slightly open. Like swirl, sonic noise will only dissipate on a
bend so it is important to install fl ow meters out of line of sight of
valves. Sonic noise is caused by liquid obtaining sonic velocities
through a slightly open valve which has a pressure diff erence
across it. This noise travels both up and down stream from
the valve therefore the fl ow meter must be installed well
away from the valve, preferably around a bend (See Figure
A3).
RUN PROGRAM RELAY 1 RELAY 2
FIGURE A1 - TURBULENCE
FIGURE A2 - SWIRL
FIGURE A3 - SONIC NOISE