Emerson Micro Motion 3711, Configuration And Use Manual, Page: 54 / 234

46 Micro Motion
®
Model 3711 Gas Flow Computers
Configuring the Core Interface
5.6 Zeroing the meter
Zeroing the meter establishes the system’s point of reference when there is no flow. The meter should
be zeroed when it is first installed.
When you zero the meter, you may need to adjust the zero time parameter. Zero time is the amount of
time the transmitter takes to determine its zero-flow reference point. The default zero time is
20 seconds.
• A long zero time may produce a more accurate zero reference but is more likely to result in a
zero failure. This is due to the increased possibility of noisy flow, which causes incorrect
calibration.
• A short zero time is less likely to result in a zero failure but may produce a less accurate zero
reference.
For most applications, the default zero time is appropriate.
Note: Do not zero the meter if a sensor status alarm or core processor status alarm is active (see
Section 13.4). Correct the problem, then zero the meter.
To zero the meter:
1. Apply power to the system. Allow the sensor to warm up for approximately 20 minutes.
2. Run the process fluid through the sensor until the sensor temperature reaches the normal
process operating temperature.
3. Click Meter > Calibration . The dialog box shown in Figure 5-6 is displayed.
Figure 5-6 Gas Flow Computer Calibration dialog box