5" String Wound PP Cartridge 20 Micron NSF - Aquapro

5" string wound PP cartridge - 20 micron

Sediment filter cartridge in wound polypropylene fibre, 5" long, 20 micron rating. NSF certified. Aquapro reference PR-PPS-05-20.

5" is the compact format in the range, designed for installations where available height is the main constraint: a crowded under-sink cabinet, a compact RO unit, built-in assemblies, shallow cabinetry.

Wound fibre

The media is a polypropylene yarn wound in crossed layers around a central core. Tension and winding pitch are calculated so that density increases inwards: the mesh is open at the surface and tightens with depth.

Water therefore passes through progressive filtration. Coarse particles are stopped in the outer layers, finer ones travel further before being retained.

The result is depth filtration: the cartridge uses its full volume instead of blinding on its outer face alone. Against a surface media, it offers higher dirt-holding capacity and longer service life at equivalent rating.

That matters especially in 5": the filtration volume is inherently limited, so every cubic centimetre of media has to work.

Polypropylene is chemically inert and tolerates a wide pH range. It releases nothing into the water, which the NSF certification confirms in terms of materials in contact with drinking water.

Why 20 micron

20 micron is a coarse duty rating. It is not there to clarify the water but to absorb the load: sand, rust, clay particles, pipe deposits.

On a 5" format, that choice makes sense. A fine rating, 1 or 5 µm, in such a small volume would saturate very quickly as soon as the water is loaded. 20 µm lets the fines through but captures the bulk of the load without blinding within weeks.

Fitted at the head, the 20 µm cartridge lightens the work of the following stages, fine cartridge, carbon, membrane, and directly extends their life. That is exactly what a first stage is for.

Where to use it

As prefiltration in a 5" housing, as the first stage of a compact RO unit, on under-sink installations short on height, and as mechanical protection for any equipment connected downstream.

Replacement

Replacement is judged on pressure drop, not on the calendar. A noticeable drop in flow, or a rising differential pressure across the filter, signals a saturated cartridge.

In practice, count on 3 to 6 months depending on water quality, shorter on loaded water, and the 5" format, smaller than a 10", logically saturates faster at equal load.

A cartridge left in place too long does more than throttle flow: under pressure it can release part of the particles it had captured.

Fitting

Shut off the water and depressurise before opening the housing. Follow the flow direction.

On reassembly, grease the bowl O-ring with food-grade silicone grease and check that it is clean, correctly seated in its groove and untwisted: this is the first cause of leaks on a filter housing.