Headbox head loss

1. Check gaskets in an air loaded headbox for leaks.
— it may be necessary, as a temporary measure, to provide an auxiliary source of air.
— air pressure loss allows box to fill up, but head will remain relatively constant.
2. Check for cavitation in fan pump.
3. Examine charts for automatic control valve position.
— check headbox automatic pressure controls.
4. Check levels on suction side of fan pump, e.g., deculator level and pressure, wire pit level.
5. Examine system pressures for signs of blockage.
— e.g., a piece of screen plate broken away and lodged in a valve.
6 Check headbox for leaks.
— e.g., headbox pump valve may be partially open.
7. The main control valve after the fan pump could generally be opened further if there is no system malfunction.
— i.e., loss of temperature in a high temperature system would give loss of total head.
8. Alternatively, the slice could be lowered.
— this has minimal effect on suction breast roll headboxes.
9. Check for plugged selectifier screens.