IM-P198-02
MI Issue 5
88
9.5 Inaccurate output
1.
Verify the piping installation has allowed for the required straight pipe run. See Section 2.4
2.
Verify flow is within the range of the rotor. See Figure 96.
Where:
V max = maximum velocity of fluid [ft/sec (m/sec)]
V lin = minimum velocity of fluid at which rotor response is linear [ft/sec (m/sec)]
V min = minimum measurable velocity of fluid [ft/sec (m/sec)]
r = density of fluid [lbs/ft 3 (kg/m)]
N/A = No Application
3.
Check the quality of the rotor signal. To do so, look for the turbine variation warning on
the web page.
9.6 Normal rotor
The normal signal from the magnetic pickup coil is a sine wave. For a normal ten-blade
rotor, there are ten identical sinewaves per revolution.
9.7 Bent blades
Bent blades display one or more cycles, which lean away from perpendicular or drop below
the centerline.
9.8 Missing rotor
A rotor missing a blade produces an abnormal waveform or cycle. Typically, the wave
pattern will have a gap left from the missing blade.
Fig. 96