Verify The Zero - Emerson Micro Motion 9739 MVD Configuration And Use Manual

Quick start
June 2019

2.6 Verify the zero

Verifying the zero helps you determine if the stored zero value is appropriate to your installation, or if a field
zero can improve measurement accuracy.
The zero verification procedure analyzes the Live Zero value under conditions of zero flow, and compares it to
the Zero Stability range for the sensor. If the average Live Zero value is within a reasonable range, the zero
value stored in the transmitter is valid. Performing a field calibration will not improve measurement accuracy.
Important
In most cases, the factory zero is more accurate than the field zero. Do not zero the meter unless one of the
following is true:
• The zero is required by site procedures.
• The stored zero value fails the zero verification procedure.
Procedure
1. Allow the flowmeter to warm up for at least 20 minutes after applying power.
2. Run the process fluid through the sensor until the sensor temperature reaches the normal process
operating temperature.
3. Stop flow through the sensor by shutting the downstream valve, and then the upstream valve if
available.
4. Verify that the sensor is blocked in, that flow has stopped, and that the sensor is completely full of
process fluid.
5. From ProLink III, choose Device Tools → Calibration → Zero Verification and Calibration → Verify
Zero and wait until the procedure completes.
6. Observe the drive gain, temperature, and density readings. If they are stable, check the Live Zero or
Field Verification Zero value. If the average value is close to 0, you should not need to zero the meter.
7. If the zero verification procedure fails:
a) Confirm that the sensor is completely blocked in, that flow has stopped, and that the sensor is
completely full of process fluid.
b) Verify that the process fluid is not flashing or condensing, and that it does not contain particles
that can settle out.
c) Remove or reduce sources of electromechanical noise if appropriate.
d) Repeat the zero verification procedure.
e) If it fails again, zero the meter.
Postrequisites
Restore normal flow through the sensor by opening the valves.
Related information
Zero the meter
14
Configuration and Use Manual
MMI-20016855
Micro Motion 9739 MVD Transmitters