Capsule Filters for Process and High-Purity Filtration

A capsule filter is a pleated element sealed inside a molded polypropylene body — filter and housing in one disposable unit. There is no separate vessel to buy or clean. At change-out the whole capsule is replaced, removing the cleaning cycle and the cross-contamination path between batches.

A cartridge is the element only and sits in a housing you own and clean. A capsule includes the housing and is replaced complete. Cartridges cost less per change-out; capsules remove the cleaning and validation step. In regulated service that is usually the deciding factor, because a vessel cleaning cycle must be validated and documented while a disposable capsule need not be.

When the fluid is valuable, the batch is small, changeovers are frequent, or there is no window to clean and validate a vessel. Capsules also suit multi-product facilities, because replacing the whole unit removes the carry-over path between products. For continuous high-volume duty on one fluid, a cartridge and housing is usually cheaper.

Four media options: Polypropylene (PP) for general process and viscous fluids; Polyethersulfone (PES) for aqueous fluids where recovery matters, being hydrophilic and low protein-binding; PTFE for gas and vent service and aggressive chemistry, being hydrophobic with the broadest chemical resistance; and Glass Fiber for pre-filtration where dirt-holding capacity sets the change-out interval.

The N/S capsule series is rated 1 to 10 µm. PP and glass fiber are nominally rated; PES and PTFE are absolutely rated, which is what lets a process demonstrate retention. Non-standard ratings are available on request.

N/S capsules are 72mm outer diameter in five body lengths — 114, 138, 152, 183 and 202mm — with 1/4″, 3/8″ and 1/2″ NPT and Swage connections. PRI is 77mm diameter at 195, 325 or 583mm. PRS is 250mm at 378mm. Custom bodies and adaptors require new tooling, so raise them early.

N/S: 4.1 bar / 60 PSI maximum differential, 50°C standard and 100°C on PTFE configurations. PRI: 0.7 MPa design pressure, 0.3 MPa differential at 20°C, 80°C. PRS: 0.8 MPa design pressure, 0.5 MPa differential at 20°C, 80°C. Change out on differential pressure at constant flow rather than elapsed time.

We review second-source options against your operating conditions for Pall AcroPak, Whatman Polycap TC/AS/HD/SPF, Millipore Polygard and Durapore, Meissner, Sartorius, Pentair, GVS and Pureflo capsules. Send the part number, fluid, flow rate and connection type. We do not claim a match before it has been validated on your process.

Ten working days on N/S capsules, minimum order 50 pieces. Tell us your delivery location and we will confirm shipping.

In liquid process filtration the four families are depth filters, which load dirt through the thickness of the media; pleated membrane filters, which retain at a rated pore size on the surface; capsule filters, which seal an element inside a disposable housing; and bag filters, which use a sewn or welded fabric bag inside a vessel. Pullner manufactures the first three. A capsule is a format rather than a media type, so a capsule can contain either a depth media such as polypropylene or glass fiber, or a membrane such as PES or PTFE.

A membrane filter is used where a process has to demonstrate retention rather than estimate it. Depth media are nominally rated, meaning a stated percentage of particles at a given size; a membrane is absolutely rated, so it is what you specify for sterile filtration, final filtration before filling, and any duty subject to validation. In Pullner capsules the membrane options are PES for aqueous fluids where recovery matters, and PTFE for gas, venting and aggressive chemistry. Both are integrity testable in place.