7" String Wound Cartridge 25 Micron - Aquapro PR-SWS-07-25

7" string wound cartridge - 25 micron

Sediment filter cartridge in wound polypropylene, 7" long (177,8 mm), 25 micron rating. Aquapro reference PR-SWS-07-25.

The 7" format is a compact one, shorter than the standard 10". It fits small filter housings and installations where available height is limited, under-sink, inside a cabinet, in built-in assemblies.

The winding

The media is a polypropylene yarn wound in crossed layers around a central core. This is not a plain winding: tension and 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, all the more useful on a short format, whose filtration volume is inherently limited.

Polypropylene is chemically inert and tolerates a wide pH range. It releases nothing into the water.

Why 25 micron

25 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, fragments shed by the network.

On loaded water, this is the rating that avoids blinding within weeks. Fitted at the head, the 25 µm cartridge lightens the work of finer stages, 10 µm, 5 µm, carbon, membrane, and directly extends their life. Without it, the more expensive fine cartridge absorbs everything and is replaced three times as often.

On already clear water, 25 µm can also stand alone as simple mechanical protection for a piece of equipment.

Where to use it

As prefiltration in a 7" housing, on compact installations short on height, protecting a softener, water heater, pump or tapware, and as a first stage on well or borehole water, often heavily loaded with particles.

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, shorter on loaded water, and the 7" 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.