Application

Inline Screening in Conveying and Processing Lines

Answer in brief

Screen inside the line with an in-line centrifugal sifter: mounted in the conveying route or under the receiver, it checks product at full rate in an enclosed housing, discharges oversize through a separate contained port and preserves the line's vacuum or pressure regime. The result is foreign-material control without breaking containment or adding a transfer step.

Reviewed August 14, 2026 · Updated August 14, 2026

The problem

A stand-alone screener interrupts an otherwise closed conveying route: product leaves the line, passes an open machine with its own dust, cleaning and footprint burden, and re-enters the process. Every interruption is a contamination interface, an operator exposure point and floor space. Yet skipping the screen is not an option where specifications demand foreign-material control — the question becomes where screening can happen without breaking containment.

Desired outcome

Screening should happen inside the closed route: dust-tight, inspectable, with a contained oversize discharge, and without a separate transfer step. The screen should protect the process at full conveying rate, keep the pressure or vacuum profile of the line intact, and open for inspection and cleaning as quickly as the plant's hygiene regime demands.

Process approach

Centrifugal in-line sifters dominate: mounted in the pneumatic conveying line or directly under a receiver, they screen at conveying rates in a fully enclosed housing while oversize leaves through a separate contained port. In vacuum conveying, the screener sits between receiver and process so the conveying air never bypasses the mesh. Gravity in-line screeners handle vertical routes between process floors. In every arrangement the screen housing keeps the line's pressure regime — leak-tight for vacuum, pressure-rated where lines are — and offers quick access for mesh inspection between campaigns.

Selection factors

Conveying mode and pressure regime the screener must preserve (vacuum, dilute-phase pressure, gravity). Screening duty: pure safety screening versus a defined size cut at line rate. Mesh size, blinding behavior of the product and the deblinding concept. Oversize discharge: contained, separate and sized for the real contamination rate. Inspection access and mesh-integrity checking without dismantling the line. Hygienic execution of the housing and screen assembly. Explosion-protection zoning where fine combustible dust passes the mesh.

Common failure modes

The screener leaks conveying air, and vacuum or pressure capacity quietly drops.
Mesh sized for the specification blinds at line rate and chokes the route.
Oversize discharges into an open bucket next to a closed line.
Mesh breakage goes unnoticed because inspection means dismantling the line.
The screener becomes the hygiene weak point of an otherwise cleanable route.
Line capacity was calculated without the screener pressure drop.

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Frequently asked questions

What is an inline sifter?

A screening machine built into the conveying route — typically a centrifugal sifter in a pneumatic line or under a vacuum receiver. It screens at conveying rate inside an enclosed housing, so the product stays contained from source to process.

Does an inline screener reduce conveying capacity?

It adds a pressure drop and, if it leaks, costs vacuum or pressure capacity directly. Correctly sized housings and leak-tight execution keep the penalty small — but the line calculation must include the screener from the start.

Where does the oversize go in a closed line?

Through a separate, contained discharge port into its own collection route. An open oversize bucket next to a closed line undoes the containment the inline concept was chosen for.

How is mesh integrity checked in an inline installation?

Through inspection access designed into the housing — quick-open covers and removable screen assemblies — on a schedule, plus downstream verification where the duty is critical. A safety screen only works while the mesh is intact.

Hanningfield Centrifugal Sifter (Kwik-Sift)

Hanningfield's Kwik-Sift video walks through centrifugal sifting — rotating assembly, cylindrical screen, and separate discharge paths for product and oversize.

20 views

Hapman

Hapman Compact Sieve Animation

Hapman's animation shows a compact vibratory sieve mounted beneath a bulk bag unloader, screening powder before it enters the next process step. The official product context describes a high-capacity, easy-clean option for restricted spaces; the animation itself is not evidence for vacuum-conveying performance.

21 views