Table of Contents
Diagnostics and troubleshooting
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pH reading in buffer drifts during manual calibration
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Check the stability limits. If the stabilization range (prompt PH) is set too narrow or
the stabilization time (prompt tIME) is set too long, the transmitter will not accept
buffer readings. A good choice for PH is 0.02, and a good choice for tIME is 10 - 20
seconds.
Allow adequate time for the temperature of the sensor to reach the temperature of
the buffer. If the sensor was in a process substantially hotter or colder than the
buffer, allow at least 20 minutes for readings in the buffer to stabilize. Alternatively,
place the sensor in a container of water at ambient temperature for 20 minutes
before starting the calibration.
Be sure to swirl the sensor after placing it in each new buffer solution.
Finally, check the sensor. Verify that wiring is correct. Also, the sensor may be dirty
or aged, or the reference junction may be depleted.
a. Check that the sensor is properly wired to the transmitter. Pay particular
attention to terminals TB-10 (mV in), TB-7 (reference), and TB-8 (solution
ground).
b. Clean the transmitter.
c. If the sensor is not rebuildable, rejuvenate the reference junction.
d. If the sensor is rebuildable, replenish the reference electrolyte and replace the
liquid junction.
e. Replace the sensor. A clean pH sensor should not drift in buffer.
Allow adequate time for the temperature of the sensor to reach the temperature of
the buffer. If the sensor was in a process substantially hotter or colder than the
buffer, allow at least 20 minutes for readings in the buffer to stabilize. Alternatively,
place the sensor in a container of water at ambient temperature for 20 minutes
before starting the calibration.
Be sure to swirl the sensor after placing it in each new buffer solution.
Finally, check the sensor. Verify that the wiring is correct. Also, the sensor may be
dirty or aged or the reference junction may be depleted.
a. Check that the sensor is properly wired to the transmitter. Pay particular
attention to terminals TB-10 (mV in), TB-7 (reference), and TB-8 (solution
ground).
b. Clean the sensor.
c. If the sensor is not rebuildable, rejuvenate the reference junction.
d. If the sensor is rebuildable, replenish the reference electrolyte and replace the
liquid junction.
e. Replace the sensor. A clean pH sensor should not drift in buffer.
Rosemount 5081
- Quick Links:
- 5081 Programming
- Manual Calibration
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Table of Contents
Troubleshooting
