Pneumatic Vacuum Conveying

Vacuum conveying offers several significant advantages over mechanical conveyors (screw, belt, bucket). Firstly, no moving parts along the conveying route means minimal maintenance and no risk of product contamination by lubricants or wear particles. Secondly, material flows in enclosed pipes – ensuring completely dust-free operation, which is critical in the food, pharmaceutical and ATEX sectors. Thirdly, pipes can be routed through walls, between floors and around obstacles – routing flexibility far exceeds that of screw or belt conveyors. Fourthly, in the event of a leak in a vacuum system, material does not escape to the environment (unlike pressure conveying), which improves safety. Additionally, a vacuum system makes it easy to pick up material from multiple sources (sacks, bulk bags, silos) and deliver it to a single destination.

Yes – this is one of the main advantages of vacuum conveying. Unlike mechanical conveyors (which require straight-line routes and large installation footprints), vacuum conveying pipes are only 38–100 mm in diameter and can be routed in any direction – vertically, horizontally, through walls, floors, service shafts and around existing equipment. As an engineering company, we design every system individually based on a site survey – taking into account existing infrastructure, spatial constraints, pick-up and destination locations, as well as future expansion. The vacuum generator can be located in a separate room from the receiver, further saving space in the production area.

Dense-phase (low-velocity) conveying is recommended in three key situations. Firstly, when the material is friable or fragile – e.g. flakes, crystals, tablets, granules – and standard dilute-phase velocity would cause breakage or attrition. Secondly, when the material has been pre-blended and maintaining mixture homogeneity is important – low velocity minimises segregation of components with different densities and particle sizes. Thirdly, when the material is highly abrasive (e.g. minerals, quartz) – low velocity significantly reduces pipe and elbow wear. Dense-phase conveying requires a higher vacuum level (rotary vane or claw pump instead of a side-channel blower), but consumes less energy per tonne of material conveyed.

Yes – this is our key differentiator. Many suppliers offer packaged vacuum systems with standard throughputs and configurations. As an engineering company, we approach every project individually: we select the receiver type and size to match the required throughput and cycle time, design the pipeline route taking into account existing obstacles and spatial constraints, select the appropriate pump type for the material properties and conveying distance, and integrate the system with existing process equipment – feeders, bulk bag stations, mixers, scales and control systems. We also manufacture receivers with non-standard capacities when the process demands it. We offer full support – from site survey, through design, manufacturing and installation, to commissioning and after-sales service.

The vacuum receiver is mounted directly above the feeder hopper. When the level sensor in the feeder signals a low material level, the controller initiates a conveying cycle – material is drawn into the receiver, filtered, and then discharged by gravity into the feeder hopper once the discharge valve opens. The refill cycle is synchronised with feeder operation so that replenishment does not interfere with the feeding process (refill occurs at the appropriate point in the loss-in-weight cycle). In multi-feeder systems, diverter valves are used so that a single receiver can sequentially supply several feeders, or dedicated receivers are installed above each feeder.

Virtually all dry bulk solids – from fine powders (flour, icing sugar, cocoa, titanium dioxide, fly ash) through granules (PE/PP/PVC plastics, fertiliser granules, pellets) to friable materials (flakes, crystals, tablets) and abrasive products (cement, lime, quartz sand). The key is selecting the appropriate conveying mode: dilute phase for standard materials, dense phase for fragile and abrasive ones. We also match the pipe material (stainless steel, carbon steel or plastic) to the product characteristics and industry requirements. The only limitation is wet, moist or highly adhesive materials – in such cases we recommend a consultation with our application engineer.

Yes – a vacuum receiver mounted on load cells becomes a gain-in-weight scale and can serve as a precision batch weighing device. The operating principle is as follows: the control system initiates a suction cycle and monitors the mass increase in the receiver in real time. When the scale reaches the target setpoint, the controller immediately closes the conveying-line valve, ending the suction phase. Then – once the weight reading has stabilised – the discharge valve opens and the weighed batch drops by gravity into the process, e.g. a mixer, reactor or process vessel. Weighing accuracy in such an arrangement is typically below ±1 % of the setpoint. The control system can handle multi-component recipes – sequentially drawing in and weighing successive ingredients into the same receiver before discharging the entire batch. This solution is particularly beneficial where dust-free, contained ingredient dispensing is required without operator contact with the material, e.g. in the pharmaceutical sector or when handling toxic substances. At InterProcess, we design both the weighing arrangement and a dedicated PLC + HMI control system, ensuring full integration with the plant’s supervisory automation.

Advantages of multi-stage ejectors: no moving parts and no electrical supply, instant on/off switching, minimal maintenance, can be mounted directly at the receiver (decentralised). Advantages of a centralised mechanical pump system (blower, Roots, rotary vane): in continuous duty a mechanical pump is approx. 3× more energy-efficient – compressed air is one of the most expensive utilities in industry. A single central vacuum generator can sequentially serve multiple conveying lines from one location. No need for an extensive compressed-air installation (compressor, dryer, filters, distribution network). Easier capacity scaling – the pump is sized for the total plant requirement. When an ejector, when a mechanical pump? A multi-stage ejector is optimal when: the plant already has a high-capacity compressed-air installation, the system serves single lines at low to medium throughput, or operation in an ATEX zone without electrical supply is required. A centralised mechanical pump system is the better choice when: the plant requires multiple conveying lines operating simultaneously, throughputs are high and operation approaches continuous duty, there is no compressed-air installation or expanding it would be costly, or minimising energy cost per tonne of conveyed material is a key criterion. At InterProcess, we select the generator type individually for each project – analysing available utilities, process requirements, distances and throughputs to propose the most cost-effective and technically optimal solution.