Volkmann vacuum conveying
Vacuum conveyors are generally used to transport bulk materials. As a general rule, the term ‘bulk materials’ usually refers to powder and granules, wherein – up to a certain particle size – seeds, tablets, pills, capsules, flakes, pellets and even larger pieces are conveyed. Through the use of special vacuum generators which can achieve a high vacuum level, it is also possible to transport liquids and viscous media (for information, refer to the VOLKMANN wet vacuum). In addition to the particle size of the solids (particle size distribution) the density of the bulk material plays an important role in vacuum conveying. In the extreme case, this can be in the range of approx. 0.05 kg/l (e.g., fluidized pyrogenic silica) to approx. 13 kg/l (e.g. uranium compounds). However, the densities are most frequently in the range of between 0.1 to 2.5 kg/l. VOLKMANN vacuum conveyors are constructed in a modular fashion and as a result, they can be adapted to the individual conveying task so that almost all types of bulk materials can be conveyed. There are even special solutions for “critical materials”, e.g. for wet, oily, adhesive, bridging, hygroscopic, poor-flowing and explosive materials. Even nanoparticles have been successfully transported pneumatically by vacuum.

Advantages
Unlike mechanical conveyors, a vacuum is the only thing which is needed in order to move the material. It is possible to eliminate mechanical parts in the product stream. This vacuum technology operates in contrast to mechanical conveyors and offers numerous advantages: In the conveying of critical bulk solids, there are often high demands in terms of the seal quality of the conveyor systems. In essence, this can be achieved more easily with
negative pressure than with positive pressure or mechanical conveyors. As such, vacuum conveying is a particular form of pneumatic conveying. Vacuum conveying uses negative air pressure to move product and is a good solution for all materials where release into the environment should be
avoided, whether this is to protect staff or the environment. Vacuum conveying actively contributes towards the goal of achieving “Clean premises” and helps to avoid the build up of potentially explosive dust. The modular design allows VOLKMANN vacuum conveyors to be individually adapted for
application where containment conditions (closed systems) are desirable. WIP (Wetting in place) and CIP (Cleaning in place) are examples for further stages of design.

Performance range
The only criteria that limits the application is the available pressure difference of 1 bar max. (i.e. the difference between the prevailing air pressure and 0 bar absolute) and – from the point of view of safeguarding against explosions – a small conveyor diameter is preferred and with it, the achievable
maximum flow rate (depending on the individual case, currently limited to approx. 10 t/h). Conveying distances of up to 80 m as well as conveying heights of up to 35 m (and in some cases more) are achievable . In most applications however, the distances run to 40 m and heights extend to
20 m.

Transportation of bulk material
• maximum flow rate 10 t/h
• Conveying distances of up to 80 m
• conveying heights of up to 35 m