Cement butterfly valve does not open or close
Symptom
The cement scale keeps creeping up with the screw stopped, the valve does not open fully, or the panel shows the wrong valve position.
Likely causes
- Worn seat or cement packed on the seat, so the disc does not seal.
- Cement on the disc, low actuator air pressure, or a worn actuator.
- Burnt solenoid coil, or a stuck solenoid spool from water in the air.
- Valve body carrying the weight of the screw, or over-tightened flange studs.
- Dirty or misadjusted position switch.
Most likely and cheapest to check first.
Checks
- Watch the cement scale with the screw stopped and the valve closed. Any rise is a leak.
- Check actuator air pressure and the position indicator.
- Measure the voltage at the solenoid coil; try the manual override.
- Check the screw has its own supports and does not hang on the valve.
Fix
- Clean the disc and seat; fit a new seat and bushings.
- Restore air pressure; repair or replace the actuator.
- Replace the coil or the solenoid valve; dry the compressed air.
- Fit screw supports; replace a cracked valve body.
- Clean and adjust the position switch.
Parts you may need
Why a small leak costs every batch
A valve that does not close tightly lets cement drift into the screw and the scale after the target is reached. The scale then overshoots on every batch, and the recipe changes without anyone seeing it on the screen.
CAUTIONThe butterfly valve is not a support. If the screw hangs on the valve flange, the body cracks and the seat distorts.
FIELD TIPWhen ordering a seat, give the nominal size (e.g. 200, 250 or 300 mm), single or double flange, disc material and actuator type, with a photo of the plate.
⚠ Every check inside a machine starts with full lockout. Safety disclaimer