Emerson Micro Motion SGM Series - Density Measurement Problems

14.7 Density measurement problems
Density measurement problems and recommended actionsTable 14-3:
Problem Possible causes Recommended actions
Erratic density reading • Normal process noise
• Line pressure too low
• Flow rate too high
• Pipe diameter too small
• Condensation or deposition on the vibrat-
ing element or the internal walls of the cyl-
inder
• Contaminants or suspended solids in the
process gas
• Vibration in the pipeline
• Leakage from the reference chamber
• Malfunction of the pressure control valve
• Erosion or corrosion
• Check your process conditions.
• Increase the density damping value.
• Reduce the flow rate.
• Ensure that line pressure or sample pres-
sure meets installation requirements.
• Increase back pressure to minimize bubble
formation.
• Minimize vibration in the pipeline.
• Check the coalescing filter. See
Section 14.21.
• Check for leakage. See Section 14.20.
• Increase the pipe diameter.
• Install a flow control method (bypass, flow
chamber, expander, etc.).
• Perform Known Density Verification.
Inaccurate density
reading
• Inaccurate temperature measurement
• Incorrect calibration factors
• Leakage from the reference chamber or in-
to the reference chamber
• Condensation or deposition on the vibrat-
ing element or the internal walls of the cyl-
inder
• Contaminants or suspended solids in the
process gas
• Verify the temperature reading from the
RTD (on-board temperature sensor).
• Verify the temperature reading from the
external temperature device, if applicable.
• Check the coalescing filter. See
Section 14.21.
• Increase the flow rate.
• Install a thermal insulation jacket.
• Verify the calibration factors.
• Ensure that the cylinder is positioned cor-
rectly.
• Perform Known Density Verification.
• Check for leakage. See Section 14.20.
Density reading too
high
• Condensation or deposition on the vibrat-
ing element or the internal walls of the cyl-
inder
• Leakage from the sample path into the ref-
erence chamber
• Corrosion, dents, scratches, or other dam-
age to the cylinder
• Check the coalescing filter. See
Section 14.21.
• Check for leakage. See Section 14.20.
• Replace the meter.
Density reading too
low
• Leakage from the reference chamber to
the atmosphere
• Leaks in the pipework or fittings
• Check for leakage. See Section 14.20.
Troubleshooting
Configuration and Use Manual 157