Slotted Approach-Flow Screen

The company approach to headbox screening combines the unique advantages of Inward-Flo screening with the proven efficiency of fine slotted screens to deliver highly effective screening systems.

Based on a technology used in over 1,000 approach-flow installations around the world, the SPM and SPH Pressure Screens provide:

• Excellent screening efficiencies
• Significantly lower pulsations
• Greater paper-machine running efficiencies
• Dramatic improvements in paper product quality
• Best possible protection ahead of the paper machine

The SPM/SPH is a large-volume slotted screening system, installed as the final protection ahead of the paper machine. A typical installation consists of a .o1o in. slotted screen in the primary position and a .006 in. screen in the final stage.

Approach-flow systems using the screens achieve efficiencies greater than 90%, while much lower efficiencies are realized with most centrifugal screening systems.

Installation of SPM/SPH equipment improves paper-machine efficiency and payback is realized in a very short period.

The factors contribute to this quality performance:

• In the SPM/SPH, the stock approaches the screen at a very low tangent, reducing the effective size of the opening resulting in highest efficiency.
• The travel of the stock around the outside of the screen causes separation of heavy contaminants through centrifugal force. These contaminants do not approach the screen plate, but move along the outside wall of the chamber with the lighter rejects that have been lifted away from the screen by the rotor.
• The MicroVortex slots provide more efficient geometry for screening than perforations or other slots.