Why Flowserve Logix 520MD Plus Valve Positioners show unexpected valve position readings?
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Emma BarberAug 2, 2025
If your Flowserve Valve Positioners show valve position readings that are not as expected, consider the following:
* The stem position sensor mounting may be off by 180 degrees. Reposition the sensor.
* The stroke may not be calibrated. Perform a Stroke calibration (Quick-Cal).
* Tight shutoff MPC (Minimum position cutoff) might be active. Verify Tight Shutoff settings.
* Custom characterization or soft stops could be active. Verify custom characterization or soft-stop limits.
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Christina LoganAug 7, 2025
What to do if Flowserve Logix 520MD Plus are fully open/closed and unresponsive?
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Jessica MorenoAug 7, 2025
If your Flowserve Valve Positioner is stuck fully open or closed and doesn't respond to commands, consider these potential causes:
1. The stroke might not be calibrated. Perform a stroke calibration (Quick-Cal).
2. The inner-loop hall sensor could be disconnected. Verify hardware connections.
3. The wrong air action may have been entered in the software. Check ATO (Air-to-open) and ATC (Air-to-Close) settings and recalibrate using Quick-Cal to apply settings.
4. Actuator tubing might be backward. Verify ATO/ATC actuator tubing.
5. The electro-pneumatic converter may be malfunctioning. Replace the electro-pneumatic converter.
6. The control parameter inner-loop offset may be too high or low. Adjust the inner-loop and see if proper control resumes.
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Johnny ReidAug 11, 2025
How to fix sticking/hunting operation of Flowserve Valve Positioners?
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cynthiahumphreyAug 12, 2025
If your Flowserve Valve Positioner is exhibiting sticking or hunting behavior, consider the following:
1. Contamination of the electro-pneumatic converter. Check the air supply for proper filtering and meeting ISA specifications ISA-7.0.01.
2. Incorrect control tuning parameters. Lower proportional gain settings.
3. High packing friction. Enable the stability DIP switch on the local interface and recalibrate. If the problem persists, adjust the pressure control window with a handheld communicator or ValveSight and recalibrate.
4. The spool valve is corroded or dirty. Disassemble and clean the spool valve.
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lauracraneAug 17, 2025
What causes erratic communications in Flowserve Valve Positioners?
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Brittany FlowersAug 17, 2025
Erratic communications in Flowserve Valve Positioners can be caused by several factors:
1. Current source bandwidth not limited to 25Hz. The maximum allowable current source rate of change is 924 mA per second.
2. Maximum cable length or cable impedance exceeded. See Section 7 ELECTRICAL CONNECTIONS.
3. HART modem connected to PC RS-232 port not receiving enough power. Verify that the laptop battery is not low.
4. Interference with I.S. barrier. You must use a HART compatible I.S. barrier.
5. Current source stripping (filtering) HART signal. Use the HART filter (VHF) available from Flowserve (FLS part-No. 10156843). Alternatively, a 250? and a 22 µF capacitor, installed according to the schematic drawing can be used to establish communication.
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Jacob KelleyAug 22, 2025
What to do if Flowserve Valve Positioners unit does not respond to analog commands?
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Amy WhiteAug 22, 2025
If your Flowserve Valve Positioner unit isn't responding to analog commands:
* The positioner might be in digital command mode. Switch to analog command mode using the procedure outlined in Section 9.3 Command Source Reset, use the ValveSight DTM, or use a handheld communicator.
* An error may have occurred during calibration. Check Status Codes, correct the calibration error, and recalibrate.
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