Multi-Deck Round Vibratory Separators: How to Order the Right Screen for Each Deck

Run a round vibratory separator? You can browse round vibratory replacement screens here — or read on to learn how a multi-deck stack is built and how to reorder the right screen for every deck.

A two- or three-deck round separator is really several screens working as one machine, and that is exactly where reorders go wrong. People measure one diameter, order one mesh, and end up with a stack that no longer makes the cut it used to. The fix is simple once you see the machine the way a service tech does: the diameter is the machine constant; the mesh is the per-deck variable. One screen per deck, each spec'd on its own.

This guide is for the maintenance tech or plant engineer who already owns a multi-deck round separator (Sweco, Kason, Midwestern, Cleveland style) and needs to install and reorder the screens correctly — without guessing, and without a machine that grades worse after the change than it did before.

How a Multi-Deck Round Separator Is Stacked

Material feeds onto the top center of the machine and is thrown outward across the cloth toward the perimeter. On a multi-deck unit, the coarsest screen sits on top and the mesh gets progressively finer going down. Oversize (the "overs") that stays on top of a deck spirals out and discharges through a discharge spout at that deck's level; everything that passes through (the "throughs") drops onto the next, finer screen below. The final fines exit the bottom.

Coarse-on-top is the standard arrangement for a physical reason: the feed hits the top deck first, so putting the coarsest screen there pulls the largest material off immediately. Each lower deck only ever sees feed that has already been cleared of everything coarser than the deck above it. Flip a fine screen onto the top and the coarse material it can't pass simply piles up, blinds the fine cloth, and can tear it under load.

One point worth getting right, because it changes how you count what you're buying: the number of decks is not the number of fractions. A separator with N screen decks produces N+1 separated fractions — one "overs" stream off each deck, plus the final throughs out the bottom. One deck gives you two fractions; Sweco builds up to four decks in a single separator for five fractions. So a "three-deck machine" is a four-product machine, and a full reorder is three screens, not four.

The Parts That Hold Each Screen

A multi-deck round separator is built from ring-shaped sections clamped into a stack. Knowing the names keeps an order clean:

• Frame section / table frame — the screen-carrying ring section at each level.
• Spacing frame (spacer frame) — the intermediate section between decks; it can carry its own discharge spout.
• Tension ring — the ring the cloth is tensioned onto (on round separators the cloth is held on a ring, not by the tension rails of a rectangular shaker).
• Clamp ring — clamps the whole stack of sections together.
• Center tie-down (CTD) — a central fastener that anchors and tensions larger, finer cloth from the middle to keep it flat.
• Gasket — one at each screen joint, not one shared for the whole machine.

That last point catches people: there is a gasket at every separation between sections, and it does real work — it seals each deck so fractions don't cross-contaminate. If you're ordering a full set, you're often ordering a gasket per joint along with the screens, in a material matched to the duty (neoprene, silicone, Buna-N, or an FDA-compliant compound for food and pharma).

Why Each Deck Needs Its Own Mesh

Each deck is a separate screen at its own mesh count, chosen for the cut that deck is supposed to make. That's the whole reason a multi-deck machine exists — to make several graded cuts in one footprint. So a complete reorder is one screen per deck, each spec'd individually, with the mesh stepping finer from top to bottom.

The two classic reorder mistakes both come from forgetting that:

• Ordering every deck at one mesh. You lose the graded cut entirely. Material that should discharge off the top deck instead works its way down to finer screens that were never meant to handle it, overloading and blinding them.
• Putting a deck's screen on the wrong level. A fine screen above a coarse one means the coarse oversize never discharges where it should; the fine cloth pegs, blinds, and can tear under the near-size load it was never sized for.

If you're unsure which mesh belongs on which deck, the safest move is to read the existing set deck by deck before anything comes off the machine. Mesh stamps are often gone or caked over, so as you pull each screen, photograph it in order and label it top-to-bottom so the set goes back exactly the way it came off — or give us a call and we'll recommend the right screen for each deck based on your material and process. To translate a target particle size into the right mesh, our guide on mesh count vs. micron rating walks through reading a sieve chart without ordering the wrong opening, and wire cloth weave types covers when a plain, twill, or dutch weave belongs on a given deck.

Installing a Fresh Stack Without Killing the Screen

Before anything comes off the machine: shut it down, lock out and tag the disconnect, and confirm the motor has fully stopped. The eccentric weights coast after power is cut, so don't work a live or coasting separator.

A new screen can fail in its first shift if it's installed in the wrong order. On screens large or fine enough to use a center tie-down, the sequence matters: tighten the clamp ring that fastens the frame stack first, then tighten the center tie-down. Do it the other way and the mesh around the CTD gets pulled and weakened as you bring the clamp ring down on it. Adjust the CTD so the screen sits level — pulled too convex or too concave, it adds tension the cloth wasn't built to carry, and the screen fails early.

Not every deck needs a CTD; it's used on the larger-diameter and finer-mesh screens that would otherwise let the cloth whip or bounce. If your set mixes a coarse top deck with no center support and a fine lower deck with a center tie-down, that's normal — spec each accordingly.

Expect product packed into every frame and spacer joint when the stack comes apart — clean each one out before you restack, and inspect the gaskets as you go. A gasket that's crushed, swollen, or hardened won't reseal; put it on the reorder rather than fighting it back in.

Whether your machine runs loose (field-tensioned) mesh or drop-in pre-tensioned screens changes your changeover time too. The screen itself tells the story: a pre-tensioned screen drops in in roughly 2–5 minutes, while loose cloth you tension by hand runs more like 15–30 minutes. Budget more than that for the full job on a stacked machine — you still have to break the clamp ring, lift each section off, clean the joints, and reseat gaskets — but the field-tensioning penalty multiplies by every deck, which is worth weighing if you're chasing shutdown time.

Blinding Hits the Bottom Decks First

On a multi-deck machine, blinding and pegging almost always bite the finer lower decks first — they have the smallest openings and the least open area, so near-size particles wedge in and shut the cloth down. That's where anti-blinding aids belong. A ball tray — a perforated tray of rubber or silicone balls mounted beneath the mesh — bounces particles loose from the underside and is most useful on coarser cuts — roughly 4 to 40 mesh as a rule of thumb, with the crossover depending on ball size and your cut. On finer decks the ball impact can stretch the wire, which is where slider rings (clean rings) take over, sweeping near-size material off the underside. Both are built into a "sandwich" of the working screen over a support screen, and they're spec'd per deck — usually on the lower ones doing the fine work.

More Decks Means More Fractions — Not More Throughput

A common assumption is that adding decks adds capacity. It doesn't. More decks give you more fractions in the same footprint, not more tons per hour. Throughput is governed by the screening area (diameter), the open area of the cloth, and how hard the finest, limiting deck is being pushed. That bottom deck — smaller openings, most prone to blinding — sets the machine's effective rate, not the number of decks above it. If a multi-deck machine is running slow, the answer is usually the limiting deck's mesh, condition, or an anti-blinding aid, not "add another deck."

How to Spec a Full Screen Set for Reorder

Before you call, capture this — it's the difference between a set that drops in and a second order to fix the first:

1. Machine make and model — off the nameplate on the frame or motor housing.
2. Screen diameter — measure the outside diameter of the screen frame ring itself (not the machine body or the clamp band), across the widest point. It's the same across every deck of one machine, so you read it once.
3. Number of decks — how many screens are in the stack.
4. Mesh per deck, top to bottom — the per-deck variable; list each one in order.
5. Screen type and frame construction — loose mesh vs. pre-tensioned/epoxy-bonded ring, plus the clamp and gasket interfaces. Decks can differ in frame height and mounting, so confirm each, not just the diameter.
6. Material grade — 304 or 316 stainless for wet or corrosive duty, magnetic 430 where a downstream metal detector or magnetic separator needs the cloth to be detectable, carbon steel, as the application demands.
7. Gasket material — one per joint, matched to the product (including FDA-compliant for food and pharma).

If the nameplate is gone or unreadable, measure the diameter and frame height and send photos of the machine and the screen assembly — we can work from that. Our pages on what replacement screen fits a Sweco and how to measure a vibratory screener screen walk the measurements step by step, and our Sweco replacement screens page covers the build options.

And don't let a standard size list box you in. The common replacement diameters — 18", 24", 30", 36", 40", 48", 60", and 72" — cover most machines, but which of those a given maker built as a factory standard varies brand to brand, and we cut beyond the list regardless. We build screens to any size, for any machine, in whatever mesh, wire, weave, or alloy the job needs — including the odd deck height or the off-size machine a stock catalog won't cover. If your equipment or material is unusual, that flexibility is the reason to build the set with us. Every screen is built to fit your machine, or we make it right.

Not sure whether a multi-deck machine is even the right tool for your job, versus a single-deck unit? Our comparison of single-deck vs. multi-deck screeners covers that decision.

Frequently Asked Questions

How many screens does a multi-deck round separator need when I reorder?

One screen per deck. A separator with N decks produces N+1 fractions — one "overs" stream off each deck plus the final fines out the bottom — but you only order one screen per physical deck. So a three-deck machine takes three screens (and makes four products).

Can I run the same mesh on every deck?

No — that defeats the purpose of a multi-deck machine. Each deck carries its own mesh, stepping finer from top to bottom, so the machine makes a series of graded cuts. Running one mesh throughout means coarse material reaches finer screens it can't handle, overloading and blinding them.

Which screen goes on top, coarse or fine?

Coarsest on top, finest on the bottom, always. The feed lands on the top deck first, so the coarsest screen pulls the largest material off immediately and protects the finer screens below. A fine screen on top blinds and can tear.

Is the screen diameter the same on every deck?

Yes. Diameter is a machine-level dimension — you measure it once. What changes deck to deck is the mesh (and sometimes the frame height and whether a deck uses a center tie-down), so spec each deck individually even though the diameter is shared.

Does each deck have its own gasket?

Yes — there's a gasket at every screen joint, not one shared gasket for the machine. Each one seals its deck so the separated fractions don't cross-contaminate. A full reorder usually includes a gasket per joint in a material matched to your product.

Why is my multi-deck machine running slow if I added a deck?

More decks add fractions, not throughput. Capacity is set by the diameter, the open area of the cloth, and the finest "limiting" deck — the bottom one with the smallest openings and the most blinding. If the machine is slow, look at that deck's mesh, condition, or an anti-blinding aid rather than the deck count.

Order Your Full Screen Set

Whether you need a single deck remeshed or a complete three-deck set built to spec, we'll match each screen to its deck and make sure the stack drops in and grades the way it should. Browse round vibratory replacement screens, send us your old screens for rescreening, or call 866-265-1575 for a quote — tell us your machine and the mesh on each deck and we'll spec the set with you. Multi-deck sets are built to order today; online ordering for round separator screens is coming soon. Questions on your machine? Contact us and we'll help you get every deck right.