Badger Meter Vortex Meters - Manual (Page 28)

26 Form No. 09-VRX-UM-00007
SYMPTOM - Erratic Flow Indication
Check that there is at least 8 VDC present across the two terminal block screws.
Check for material clogging the flow meter and in the upstream piping.
Check for erosion of the bluff body by sighting down the meters bore. Erosion or damage to the bluff
body will cause erratic readings and compromise accuracy. If the erosion continues, the flow meter will
need to be periodically replaced.
Check upstream piping to assure that the required piping is used. (See the piping requirements specifi-
cations starting on page 2 for this information.)
Check for pipe vibration. Normal amounts of pipe vibration are easily tolerated. In addition to this, the
transmitter module contains a highly effective active filter that rejects false signals caused by pipe vibra-
tion. This filter is most effective under flowing conditions. If vibration is causing the meter to indicate
flow when the flow is stopped it will most likely not cause error under flowing conditions. The false flow
indication may be ignored, or the pipe may be restrained by firm clamps, or the noise adjustment may
be readjusted. Be sure to read the noise adjustment instructions.
Check for electrical noise. Under some conditions there can be high common mode AC noise present
between the fluid and the power supply ground. The flow meter is designed to reject up to 50 volts of AC
common mode noise without loss of accuracy. If metal piping is used, place a ground strap on the pipe
on both sides of the flow meter (the flow meter is made of non-conductive plastic) and connect them
both to the one point where the loop is grounded (see wiring diagrams starting on page 9). If plastic pip-
ing is used, a grounding orifice should be used. The transmitter module contains a highly effective active
filter that will reject false signals due to high common mode voltage. This filter is most effective under
flowing conditions. If a false indication of flow is encountered at zero flow, it will probably not cause error
under flowing conditions. In addition, the noise adjustment may be used, but it will reduce the ability of
the flow meter to measure low flow rates. See the noise adjustment instructions before attempting to
make this adjustment.
OVER-STRESSED SENSOR
If the maximum permitted flow rate of 125% of Recommended capacity (100% of HT meters) is exceed-
ed, it is possible to over-stress the sensor.