The vacuum weighing technology which has been developed by AZO in the seventies is still a fast seller.
Mixing and agglomeration processes are playing an important role. There are complex engineering processes behind many products, influencing the product properties and quality significantly e. g. taste, flowability and durability. The foundation stone for a top quality is laid by means of the feeding. Vacuum weighing system have an important contribution especially if the concern is to transport large quantities right to the point.
Conveying, dosing and weighing
Pneumatic conveying systems are enforced in comparison to mechanical conveying systems. There is often a discussion if it makes more sense to use a vacuum or a pressure conveying system. The fact is – no engineer can turn around physical circumstances. Arguments are that pollutions can get into vacuum systems if there are leakages or that dust has an effect to the ATEX-subject in pressure systems. If systems are installed professionally no such problems occur with vacuum or with pressure operations.
Vacuum conveying systems make sense if conveying from many product feeding stations to a few intake places are concerned. Product intake with vacuum conveying is easy and dust-free since no overpressure is arising. Every time the blower is at the end of the system and generates an underpressure, suctioning the product to be conveyed through the pipes.
Pressure conveying systems make sense if conveying over long distances from one product feeding station to many intake places is concerned. Since the product has to be dosed against the air steam, rotary valves or pressure hoppers are necessary. Otherwise the product intake is easier. At any time the blower is located at the beginning of a system and generates the pressure, blowing the product through the pipes by means of pressure.
A combination of vacuum and pressure conveying systems makes sense if there is a conveying from many product feeding stations to many intake places. For sensitive raw materials impulse conveying systems are used, working with a speed of 1-4 m/sec. and are therefore more gently in conveying. These systems are more cost intensive due to the necessary technical complexity.
For the reached weighing and dosing accuracy the dosing units of the product feeding are essential. In comfortable systems the dosing units are frequency controlled i. e. the conveying stream is thinned out in the verge of reaching the nominal weight (1:10) in order to reach very high accuracies.
Within a single-pipe system one conveying pipe is installed below all of the product feeding stations (feeding hoppers, big bag discharge stations resp outdoor or indoor silos) up to the conveying scale.
The difference of a multi-pipe system is that an individual pipe is installed from each product feeding place to a multi-pipe valve near the scale which includes a fresh air or dosing valve and is connected to the conveying scale. The advantage of this system is that the dosing of the multi-pipe valve is steadily the same and therefore a higher accuracy can be reached as with a single-pipe system.
Central weighing system
If many feeding and intake places are fed a central weighing system is the alternative. With such a system the individual components are conveyed into a central conveying scale and are weighed at the same time. When the batch is prepared it will be transferred into a buffer hopper and conveyed to several consumers e. g. mixers by means of pressure conveying. Prepara-tion of the next batch is done parallel in the central scale in order to reach high throughput capacities.
Other products from
Vacuum weighing systems is assigned to following product groups:
Basic processing technologies for powder and bulk material (1319)
- Size reduction (372)
- Mixing (472)
- Separating, screening, filtering (666)
Plant engineering and processing components (1367)
- Dosing (385)
- Emptying (311)
Conveying, transport, storage (737)
- Fluidising, aeration, air cannons (106)
- Conveyor systems (235)
- Pneumatic conveyors (192)
- Screws (132)
- Vibrating hoppers (63)
- Silos and silo equipment (239)
- Tanks (76)
- Hoppers (121)
- Vacuum conveyors (117)
- Loading and unloading equipment (105)
- Vibrators (70)
- Other conveying, transport, storage equipment and accessories (212)
- Pipe technologies (235)
Safety and environmental technologies (649)
- Process safety (37)
- Non-electrical explosion protection (141)
- Emission protection (218)
- Workplace safety (72)