Why V-Profile Wire Resists Blinding | ERQI WIRE

Two different failures get called a blocked screen, and they need different answers. Blinding is particles wedged into the slot that a backwash will not shift. Wear is the slot edge rubbed open until the cut point has moved. Pull the screen and look at the opening: a blinded slot is still the shape it was made, a worn one is flared into a trumpet. Getting this wrong sends people to the wrong fix — buying a coarser screen to solve a wear problem just loses product.

Why a round wire or a drilled hole jams

A particle entering a parallel-walled slot touches wall against wall. The contact is broad, the friction is high, and the passage behind it is the same width as the entrance — there is nowhere for the grain to go except deeper in, tighter. Backwash makes it worse: the flush water pushes from the same side the particle came in, driving it in rather than lifting it out. This is why plain perforated plate and woven mesh blind on duty that a wedge wire screen handles for years.

Three reasons a V-shaped slot clears

The passage widens inward. A grain that squeezes past the narrow face is through the hardest part and drops away. It cannot become a permanent resident because there is no constant-width throat to hold it.

Contact is two lines, not two faces. The wire presents two edges to the particle, so the touching area is a fraction of what a drilled hole gives. Less area, less friction, and the grain lets go.

Backwash works on the big face. Water entering from the wide side presses on the whole exposed area of the lodged particle and lifts it out through the narrow side. The geometry that let it in is the geometry that lets it out.

Where it still blinds — honestly

A V-profile is a strong answer, not a universal one. Three duties defeat it:

• Fibrous or stringy material. Fibres wrap around the wire face and bridge across slots. The section behind the slot is irrelevant when the obstruction sits on top of it.
• Oily or sticky feed. Surface tension glues fines to the face. Widening the slot, heating the feed, or adding a spray bar does more than changing the wire.
• A slot set too close to the median particle size. No geometry saves a slot with no margin. If the slot is near the D50 of the feed, near-size particles will bridge on clean duty, and the answer is a wider opening, not a different profile.

What to change when it blinds anyway

Open the slot 10–20 % and check the cut point is still acceptable. Switch to a round-edge profile where the material is prone to hanging on a sharp edge. Increase backwash pressure and volume rather than frequency — short frequent flushes move less than one proper one. Where the feed is genuinely fine and sticky, ultrasonic or air-assisted cleaning is the honest route, and sometimes the honest answer is that a surface filter is the wrong choice for that stream.

The element this applies to is on the profile wire for filters page. How the opening itself is worked out is in the slot calculation, and sections are listed under wedge wire. Send us the duty and the failure mode through contact and we will say which of the three causes it looks like.