Emerson MICRO MOTION 2700 Instalační manuál stáhnout pdf (Strana 48)

38 Transmitter Configuration and Use: Series 1000 and 2000 Transmitters

Flowmeter Startup continued

5.5 Zeroing the flowmeter

Zeroing the flowmeter establishes the flowmeter’s point of reference when there is no flow.

When you zero the flowmeter, 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: In some menus, a convergence limit parameter is displayed. Micro Motion recommends that you

use the default value for convergence limit.

Note: Do not zero the flowmeter if a high severity alarm is active. Correct the problem, then zero the

flowmeter. You may zero the flowmeter if a low severity alarm is active. See Section 7.6 for

information on viewing transmitter status and alarms.

You can zero the flowmeter with the display (if the transmitter has a display), ProLink II, the

Communicator, or with the Zero button on the transmitter (Model 1500/2500 transmitters only).

If the zero procedure fails, see Section 10.6 for troubleshooting information.

5.5.1 Preparing for zero

To prepare for the zero procedure:

1. Apply power to the flowmeter. Allow the flowmeter 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. Close the shutoff valve downstream from the sensor.

4. Ensure that the sensor is completely filled with fluid.

5. Ensure that the process flow has completely stopped.

CAUTION

If fluid is flowing through the sensor, the sensor zero

calibration may be inaccurate, resulting in inaccurate

process measurement.

To improve the sensor zero calibration and measurement

accuracy, ensure that process flow through the sensor

has completely stopped.

1 2 ... 43 44 45 46 47 48 49 50 51 52 53 ... 263 264

Žádné komentáře

Emerson MICRO MOTION 2700 Instalační manuál Strana 48