A vacuum conveying system moves powder, granules or small parts through a pipe by pulling air through it — the moving air drags the material to a receiver, where a filter separates product from air and the pump exhausts the clean air. Designing one is a chain of four linked decisions: pickup velocity, air-to-material ratio, line vacuum, and from those, pump size. Get the velocity and vacuum right and the pump size follows; get them wrong and no pump will save the line.
How a vacuum conveying line works
The layout is always the same shape:
- Pickup point — a wand, pickup nozzle or hopper adaptor where material enters the airstream.
- Conveying line — the pipe through which the air-material mix flows.
- Receiver / filter-separator — material drops out and collects; a filter cleans the air.
- Vacuum pump — pulls the whole system and exhausts filtered air.
The pump is at the clean end, protected by the filter. That placement matters: it means the pump should never see the conveyed material — provided the filter is sized and maintained.
The four design decisions
1. Pickup (conveying) velocity
The air has to move fast enough to keep material suspended and sliding, or it drops out and blocks the line. Too fast wastes energy and abrades both product and pipe (and shatters friable granules). Every material has a workable velocity band — light powders convey slower, dense granules faster. Set velocity first: it fixes the airflow the pipe must carry.
2. Air-to-material ratio (phase)
Vacuum conveying is usually dilute phase — a lot of air carrying a little material, fully suspended. The air-to-material ratio (how many kg of air per kg of product) sets the airflow you need for a target throughput. Denser loadings move more product per unit of air but demand more vacuum and risk blockage; dilute loadings are forgiving but need more airflow.
3. Line vacuum
Friction of air and material against the pipe, plus lifts and bends, all cost vacuum. The longer and more convoluted the route and the heavier the loading, the deeper the line vacuum. This is the operating vacuum your pump must hold — and it is deeper than beginners expect on long or vertical runs.
4. Pump size — flow at the line vacuum
Now the pump: it must deliver the conveying airflow at the line vacuum, with margin. And here is the rule that governs every vacuum job — pumping speed derates as vacuum deepens, so you size on the effective speed at the line vacuum, never on the free-air figure. The full method is in choosing a vacuum pump by CFM and vacuum level.
| Design input | Drives | Watch for |
|---|---|---|
| Pickup velocity | Airflow (CFM / m³/hr) | Too low → line blocks; too high → abrasion |
| Air-to-material ratio | Airflow for target throughput | Dense phase needs more vacuum |
| Line length, lifts, bends | Line vacuum | Long/vertical runs pull deeper |
| Line vacuum + airflow | Pump size | Size at operating vacuum, keep margin |
Choosing the pump family
For food and pharma powder transfer, the airstream must stay clean, so the oil-free YBDVP dry pumps are the default — no oil to reach the product. Their range covers small transfer stations to substantial lines:
| Model | Power | Displacement | Vacuum |
|---|---|---|---|
| YBDVP 40 | 1.25 kW | 40 m³/hr | −850 mbar |
| YBDVP 60 | 2.2 kW | 60 m³/hr | −850 mbar |
| YBDVP 100 | 4 kW | 100 m³/hr | −850 mbar |
| YBDVP 160 | 5.5 kW | 160 m³/hr | −850 mbar |
| YBDVP 360 | 11 kW | 351 m³/hr | −850 mbar |
For non-food industrial conveying where oil is acceptable, the ACME high-vacuum pumps (750 mmHg, up to 302 m³/hr) are a cheaper deep option. If a receiver also needs blow-back cleaning of its filter, the combined YBVP vacuum-and-pressure pumps supply both from one unit. The clean-airstream reasoning for food and pharma is in vacuum pumps for pharma applications.
Filtration — the make-or-break component
The filter-separator is not an accessory; it is what stops your product ending up in the pump.
- Size the filter for the airflow and dust load, not just the pipe diameter. An undersized filter blinds fast, line vacuum climbs, and conveying stalls.
- Clean it — reverse-jet or blow-back. A filter that cannot self-clean will progressively choke the line. Blow-back is where a YBVP pressure side earns its place.
- Add a secondary / safety filter ahead of the pump on fine or valuable powder. Product in the pump is lost product and a wrecked pump.
Horizontal, vertical and the trouble spots
Where a conveying line changes direction is where it fails, so design the route as deliberately as you size the pump.
- Horizontal runs need enough velocity to keep material suspended along the whole length; material that drops out settles on the pipe floor and slowly builds a restriction.
- Vertical lifts cost the most vacuum and are the first place a marginal system blocks — the air must carry the material's weight straight up. Keep lifts as short and as few as the layout allows.
- Bends are abrasion and pressure-loss points. Long-radius bends convey better and wear slower than tight elbows; on abrasive material, wear-back bends extend line life.
- Pickup point design decides how evenly material enters the airstream. A pickup that gulps slugs of material rather than feeding it steadily causes surging and blockages no pump can smooth out.
A line with one short lift and gentle bends will run reliably on a modestly sized pump; the same throughput forced through several tight elbows and a tall lift needs a much bigger pump and still blocks more often. Route first, then size — a good route saves pump.
Reading line vacuum as a diagnostic
Fit a vacuum gauge at the pump inlet and learn its normal reading. A slow rise over days means the receiver filter is blinding and needs cleaning; a sudden jump means a blockage in the line; a fall toward atmosphere means a leak — an open pickup, a loose coupling, or a receiver lid not sealed. One gauge turns a conveying line from a black box into something you can troubleshoot at a glance, which is why it belongs on every install.
Commissioning and running
- Prove the velocity empties the line — run, stop, and confirm no material settles in horizontal runs or at the base of lifts.
- Watch line vacuum as a health signal. A slow climb means the receiver filter is blinding; a sudden spike means a blockage.
- Filter the pump inlet and keep the vane-change interval on dry pumps (vane inspection).
- Mind the exhaust — filtered air still carries fines on a marginal filter; vent it sensibly.
Vacuum conveying overlaps with vacuum lifting and handling where the "material" is discrete parts rather than powder, and you can see the wider context on the vacuum conveying applications page.
Summary
Design a vacuum conveying line in order: set pickup velocity, choose the air-to-material ratio for your throughput, calculate the line vacuum from length, lifts and loading, then size the pump for the conveying airflow at that line vacuum with margin — allowing for derating. For food and pharma use oil-free YBDVP dry pumps; for industrial duty where oil is fine, ACME; add YBVP where filter blow-back needs pressure. Above all, size and maintain the filter-separator — it is what keeps product out of the pump.
Send us the material, distance, layout and throughput and we will size the line and the pump. WhatsApp +91 9311693322 or email sales@yashblowers.org.