Micro Motion CDM100P - Discrete output problems

Density measurement problems and recommended actions (continued)Table 10-2:
Problem Possible causes Recommended actions
Density reading too
low
• Leaks in the pipework or fittings
• Incorrect calibration factors
• Inaccurate temperature measurement
• Erosion or corrosion on the sensor tubes
• Two-phase flow
• Verify the calibration factors.
• Verify the temperature reading from the
RTD (on-board temperature sensor).
• Verify the temperature reading from the
external temperature device, if applicable.
• Check for two-phase flow. See
Section 10.23.
10.8 Temperature measurement problems
Important
Temperature measurement is ISO 17025–calibrated and accredited. Do not perform a temperature
calibration or change the temperature slope. Either of these actions will invalidate the accreditation.
You may change the temperature offset.
Temperature measurement problems and recommended actionsTable 10-3:
Problem Possible causes Recommended actions
Temperature reading
significantly different
from process temper-
ature
• RTD failure
• Incorrect compensation factors
• Line temperature in bypass does not
match temperature in main line
• Verify that the temperature compensation
factors match the value on the sensor tag
or calibration sheet.
• If Alert A004, A016, or A017 is active, per-
form the actions recommended for that
alert.
Temperature reading
slightly different from
process temperature
• Sensor temperature not yet equalized
• Sensor leaking heat
• If the error is within the temperature speci-
fication for the sensor, there is no prob-
lem. If the temperature measurement is
outside the specification, contact
Micro Motion.
• The temperature of the fluid may be
changing rapidly. Allow sufficient time for
the sensor to equalize with the process flu-
id.
• Check the reading of Tube-Case Tempera-
ture Difference.
• If Alert A004, A016, or A017 is active, per-
form the actions recommended for that
alert.
• The electrical connection between the RTD
and the sensor may be damaged. This may
require replacing the sensor.
Troubleshooting
150 Micro Motion
®
Compact Density Meters (CDM)