Scouring balls

Cleaning is frequently aided mechanically. Foam balls scour the center of tubes, and hoUow-filter systems can be back-flushed. HoUow fibers and membranes attached to rigid supports can be back-pressured, thereby eliminating the pressure drop that holds redispersed films on the membrane surface. 

The tubular element Is the least susceptible to fouling and the easiest to clean. This element is widely used in ultrafiltration applications where the process streams contain suspended solids. The tubular element can be cleaned not only by chemical action but also by mechanical means. A sponge rubber ball is pumped through the tubular element with the chemical cleaning solution to scour the membrane surface. 

In the case of slurries, the wear is accelerated by the very nature of the abrasive and erosive particles. Spent mUl liners, spent mill balls, steel grading, and spent pump Unets are installed at the bottom of drop boxes to prevent wear. It is not always cost effective to design for a scouring depth equal to one third of the free fall. 

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