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Troubleshooting Measurement Errors
Appendix B Troubleshooting Measurement Errors
Troubleshooting Measurement Errors From Electromagnetic Fields
Measurement inaccuracy can be affected by numerous factors, one of these
factors is Radio Frequency (RF). The 980 Flow Meter is designed to be
resistant to RF fields and other Electromagnetic Interference (EMI), however,
RF fields at certain frequencies (at or above 10 Volt/per meter level) can
cause disturbances to measurement circuits causing inaccurate
measurements. If RF is causing measurement errors, the tranmitter(s) are
usually located near the 980 Flow Meter. When the transmitter(s) are too
close to the instrument, remove or move the transmitter farther away from the
980 Flow Meter.
The following tables provide RF frequencies and levels that can cause
measurement errors. Compare any local transmitters and its transmitting
frequency to the tables listed below.
Analog Input
Offending Frequency
(mega Hz)
Measurement Error
(milli V)
Specification
(milli V)
90.5 28 not specified
119 12 not specified
141 11 not specified
392 9 not specified
Temperature
Offending Frequency
(mega Hz)
Measurement Error
(°C)
Specification
(°C)
84 1.9 not specified
93.7 2.1 not specified
105 5.6 not specified
125 3.6 not specified
127 2.2 not specified
131 3.8 not specified
150 2.3 not specified
324 1.9 not specified
382 7.5 not specified
Level Accuracy
Offending Frequency
(mega Hz)
Measurement Error
(inch)
Specification
(inch)
31.43 1.300 0.36
44.94 0.430 0.36
374.00 0.780 0.36