When vacuum conveying over extended vertical distances, there is a possibility that during the discharge cycle (when the vacuum source is diverted from the transfer hopper) a blockage can occur due to material dropping back down the vertical convey line.
To avoid this problem, Hanningfield offer a simple solution; an air-operated Line Clearance Valve is installed at the base of the vertical convey-line. This valve opens just prior to the discharge cycle allowing the vertical line to be fully emptied before the start of the next convey cycle. The small amount of material in the vertical convey line enters the vacuum transfer hopper and is discharged with the bulk of the conveyed material after the Line Clearance Valve has closed. The Line Clearance Valve operation is fully automated and the operator does not required to make any adjustments during the conveying process.
The Line Clearance Valve is typically utilised for vertical distances over approximately 3 metres subject to the material to be conveyed and the type of installation.