PTI CLARIFLOW® SELECT™

Pleating Process
When filter media is pleated by PTI and arrayed around an inner core, the number of pleats that can used is limited by the crowding of the pleats adjacent to the core; crowding restricts the flow exiting the pleats. Increasing area by squeezing in more than a design will bear tends to compress flow passages near the core and does not increase the effective filtration area (EFA).

Select pleating places more media nearer to the outer diameter and results in a larger EFA. At the same time it reduces crowding around the core. The net effect of Select pleating is to place emphasis on reducing what is the main flow restriction of a cartridge.

The core diameter is smaller which increases the pleat height and, therefore, the area. The net effect of Select pleating is to place emphasis on reducing what is the main flow restriction of a cartridge.

Clariflow-Select Electronics Grade Polyethersulfone (PES) Membrane with Polypropylene Supports Clariflow Select is an innovation in microfilter cartridge development in which the fast flowing Clariflow PES microporous membrane has been Select pleated to further increase its performance.

The Clariflow membrane contains its smallest critical pore structure only in the middle third of its thickness, thereby greatly reducing the pressure drop of the filter to that of a membrane only a third as thick. Called Mirrored Anisotropy, a cross section of the membrane reveals a structure having coarse openings near both surfaces, and fine pores at the center. The result is a fast flowing filter.

In the construction of a pleated filter cartridge, much more filter media can be placed closer to the outer guard than nearer to the inner core. Cartridges, which have pleats that extend to the core, have a tendency to choke off the flow emerging from the pleats. Select pleating places more media nearer to the outer diameter and reduces the crowding around the core; thus further increasing the flow rate, as compared to standard cartridges.

The core diameter is smaller which increases the pleat height and therefore, the area.

The result is a microfilter cartridge having the excellent qualities of the Clariflow PES membrane, and now in a superior configuration for even higher performance. Typical applications: pad and POU application for UPW, recirculating etch baths, chemical and solvent filtration…where extraordinarily high flow rates enable the reduction in size of equipment and improvement of tool performance.

PTI is one of the leading suppliers of microfilters to the worldwide Semiconductor industry. The company is noted for its innovative engineering and its ability to solve contamination problems. Responding to the need for a higher performance filter cartridge; one which is reliable, economical, and delivers significantly higher flow rates in the smallest filtration ratings today, PTI has developed the Clariflow® Select™ filter cartridge.

Mirrored Anisotropy
The cross section of the membranes shows a structure having three regions. The middle one contains small controlled pores which define the rating of the filter. The regions on either side are coarser and protect the critical central pores during pleating. The upstream region also serves as a prefilter.

The pressure drop through a filter cartridge is, in part, proportional to the length of the flow path (normally the entire membrane thickness.) Because the flow path through the critical restricting section is only about a third of this, the pressure drop is markedly reduced resulting in greatly increased flow rates.

Application Advantages