Emerson IFT9701 instruction manual 6.2.3Flow cutoff, 6.2.4Damping

Configuration with a HART Communicator continued

7.At the detailed setup menu, choose 2 (configure field device variables).

8.At the configure field device variables menu, choose 3 (temperature unit).

9.Repeat steps 5 and 6 to choose and enter a temperature unit.

6.2.3Flow cutoff

In some sensor installations, noise caused by mechanical sources, such as valves and motors, can affect flowmeter output signals. The flow cutoff filters out noise by defining the measured value below which the milliamp output indicates zero flow.

The flow cutoff is the lowest flow rate at which the meter produces a nonzero output signal. If flow drops below the cutoff:

•The pulse output goes to 0 Hz.

•The internal totalizer stops counting.

•The meter indicates zero flow during polling from a host controller.

A default flow cutoff is entered into the flowmeter at the factory. This number can be adjusted to achieve the filter effect described above.

To adjust the flow cutoff, use the menu below and follow these steps:

1Process variables

2Diag/service

3Basic setup

4DETAILED SETUP

5Review

1Charize sensor

2CONFIG FLD DEV VAR

3Config outputs

4Device

1FLOW

2Density

3Temp unit

1Flo unit

2FLO CUTOFF

3Flo direction

4Flow damping

1.At the online menu, choose 4 (detailed setup).

2.At the detailed setup menu, choose 2 (configure field device variables).

3.At the configure field device variables menu, choose 1 (flow).

4.At the flow menu, choose 2 (flow cutoff).

5.Enter the desired flow cutoff value.

6.Press F2 (send) to send the flow cutoff to the flowmeter memory.

6.2.4Damping

Internal damping filters out noise or the effects of rapid changes in the variable without affecting measurement accuracy.

The damping value is the filter coefficient that approximates the time required for the output to achieve 63% of its new value in response to a step change at the input. The actual time depends on many factors, including sensor type and density of the process fluid. The meter rounds down the chosen damping value to the nearest programmed filter coefficient. Programmed filter coefficients, in seconds, are:

0.1 0.2 0.4 0.8 1.6 3.2 6.4 12.8

38 Model IFT9701 Transmitter Instruction Manual