Emerson Process Management 2400S Comparison and recommendations, Performing meter verification

Measurement Performance

10.2.4Comparison and recommendations

When choosing among meter verification, meter validation, and calibration, consider the following factors:

•Process interruption

-Meter verification requires approximately four minutes to perform. During these four minutes, flow can continue (provided sufficient stability is maintained); however, current process data will not be reported.

-Meter validation for density does not interrupt the process. However, meter validation for mass flow or volume flow requires process down-time for the length of the test.

-Calibration requires process down-time. In addition, density and temperature calibration require replacing the process fluid with low-density and high density fluids, or low-temperature and high-temperature fluids. Zero calibration requires stopping flow through the sensor.

•External measurement requirements

-Meter verification does not require external measurements.

-Zero calibration does not require external measurements.

-Density calibration, temperature calibration, and meter validation require external measurements. For good results, the external measurement must be highly accurate.

•Measurement adjustment

-Meter verification is an indicator of sensor condition, but does not change flowmeter internal measurement in any way.

-Meter validation does not change flowmeter internal measurement in any way. If you decide to adjust a meter factor as a result of a meter validation procedure, only the reported measurement is changed – the base measurement is not changed. You can always reverse the change by returning the meter factor to its previous value.

-Calibration changes the transmitter’s interpretation of process data, and accordingly changes the base measurement. If you perform a zero calibration, you can return to the previous zero or the factory zero. However, if you perform a density calibration or a temperature calibration, you cannot return to the previous calibration factors unless you have manually recorded them.

Micro Motion recommends that you purchase the meter verification option and perform meter verification frequently.

10.3Performing meter verification

The meter verification procedure can be performed on any process fluid. It is not necessary to match factory conditions. Meter verification is not affected by any parameters configured for flow, density, or temperature.

During the test, process conditions must be stable. To maximize stability:

•Maintain a constant temperature and pressure.

•Avoid changes to fluid composition (e.g., two-phase flow, settling, etc.).

•Maintain a constant flow. For higher test certainty, stop flow.

If stability varies outside test limits, the meter verification procedure will be aborted. Verify the stability of the process and retry the test.

Compensation

Measurement Performance

Troubleshooting

Defaults

Configuration and Use Manual 91