Chapter 4 Troubleshooting & Repair | Series |
|
|
Troubleshooting the Flow Meter
Symptom: Output at no Flow
1.The low flow cutoff is set too low. At no flow, go to the first column of the hidden diagnostics menu and record the Lvl value. The low flow cutoff must be set above this value.
2.Example: at no flow , Lvl = 25. Set the low flow cutoff in the Calibration Menu to approximately 28 and the meter will no longer read a flow rate at no flow.
Symptom: Erratic Output
1.The flow rate may be too low, just at the cutoff of the meter range, and the flow cycles above and below the cutoff making an erratic output. The meter range is stamped on the label on the outside of the electronics enclosure cover (based on appli- cation conditions when the meter was ordered). Consult the factory if necessary to confirm the meter range based on current operating conditions. It may be possible to lower the low flow cutoff to increase the meter range. See the example above for output at no flow, only this time the low flow cutoff is set too high. You can lower this value to increase the meter range as long as you do not create the output at no flow condition previ- ously described.
2.Mechanical installation may be incorrect. Verify the straight run is adequate as described in Chapter 2. For
3.The meter may be reacting to actual changes in the flow stream. The output can be smoothed using a time constant. The dis- played values can be smoothed using the time constant in the Display Menu. The analog outputs can be smoothed using the time constant in the Output Menu. A time constant of 1 will result in the change in value reaching 63% of its final value in one second. A time constant of 4 is 22%, 10 is 9.5% and 50 is 1.9% of the final value in one second. The time constant equa- tion is shown below (TC = Time Constant).