When we hear the term BlowVac, the image of a very specific truck mounted vacuum loader comes to mind. Most users associate with BlowVac a large four- axle truck with high suction power and the possibility to pressure discharge the suction material with a blowing device. Gerd Borrmann, Export Manager, Wieland Lufttechnik, tells us that there is more to it.
First of all, BlowVac stands for high-powered suction units with large collection containers which are usually mounted onto truck chassis. However, in some cases BlowVac units can also be mounted onto trailers, semi-trailers or hook lifter frames. All units have the following in common: the vacuum pump is located in the front part of the unit and is driven either by a split shaft system or by a separate diesel engine. Behind it is the collection container with the main filter. The collection containers of the various BlowVac types are always large enough to be able to work without intercept hoppers. After all, the smallest container has a collection capacity of 4.9 m¦. Another similarity is that the collection containers of all types can be tipped hydraulically to discharge the suction material. Then where are the differences? For one, the differences lie in the suction units. Eight different units are available as part of the standard programme. Additionally, for special Atex applications electrically driven units are available. For BlowVacs with very high suction power, the TG suction unit makes the most sense. TG stands for split shaft box (TrennGetriebe in German). This box is installed into the driveshaft of the truck. The operator can switch over from driving mode to suction mode. The vacuum pump is then driven by the truck engine. This has the advantage that a separate diesel engine to drive the vacuum pump is not required. But there is an additional advantage: By using the gear box of the truck, the operator can vary the speed of the vacuum pump over a large range of rotational speed. This is important when using the blowing device to discharge the suction material. For this, it is required to reduce the speed of rotation of the vacuum pump to a minimum. As the design with a split shaft box is only cost effective for high-powered suction units, we have only one TG unit which is used for the largest BlowVacs. This unit disposes of an air flow of 8200 m¦/h and a maximum vacuum of 80%.
For applications where lower suction power is sufficient or if the customer explicitly demands a separate diesel engine, the company has a large range of diesel units with engines from 42 kW to 261 kW. This corresponds to a suction power from 2100 m³/hand 50% vacuum to 8200 m³/h and 80% vacuum. The TG unit and the diesel units can be combined with three different types of containers with the following denominations: BlowVac Conic, BlowVac SL and BlowVac BigBag.
BlowVac Conic units are the most basic and most economic types. They have a relatively small collection container with a conical taper at the rear and a discharge door with a diameter of 1000 mm. BlowVac Conic units can be equipped with a blowing device to pressure discharge the suction material into silos, into pits or onto roofs. Another possibility is to discharge the suction material by gravity onto the ground or into low open containers. It is not possible to discharge into BigBags or into skip hoppers. Due to their robust, simple design BlowVac Conic units are primarily suitable for bulk material with good separation and discharge characteristics. Vacuum extraction of liquids is not possible with this type of unit. In theory, Conic containers can be combined with large suction units with 6000 m¦/h air flow or more. However, in practice this does not make sense as the simple, cost effective Conic container does not match large suction units which are complex and costly. Consequently, the company has made available BlowVac Conic units with a maximum air flow of 3700 m¦/h. Mostly, they are mounted on two axle trucks with a permissible total weight of 18 tons or alternatively on two axle trailers or hook lifter frames. Frequently, the users choose the optional blowing device. If this is the case, the unit with 3200 m¦/h delivers the best performance. This unit carries the denomination BlowVac Conic 3200 Diesel.
BlowVac SL represents the classic BlowVac with large discharge door, i.e, without conical taper at the rear. This is the standard solution for industrial cleaning contractors who require a unit to cover all possible applications. The SL container is extremely robust and disposes of a high-grade filter system for critical suction materials. The large discharge door has the advantage that sticky suction material like wet sand or viscous sludge can be safely discharged. Furthermore, the unit can be equipped to extract and transport liquids. Due to the low edge for tipping discharge, the suction material can only be dumped onto the ground. Usually customers order the sophisticated SL blowing device which achieves unique pressure discharge performances. In most cases customers who require an SL, take the largest possible unit which would be the BlowVac SL 8200 TG. This is the unit with the split shaft box. Smaller versions for three axle trucks with 4000 or 6000 m¦/h are available but are not frequently built. SL units cannot be mounted onto trailers or hook lifter frames.
BlowVac BigBag, finally, is the premium but also the most versatile member of the BlowVac family. It can only be mounted onto truck chassis and is also usually ordered with the split shaft suction unit with 8200 m¦/h air flow and 80% vacuum for four axle trucks. However, in contrast to the SL, the BlowVac BigBag 8200 TG can also be mounted onto three axle trucks. Compared to the SL, the BigBag has several advantages, the most import being the high discharge height of 1.7 m. This and the conical taper at the rear with its DN 300 hydraulic discharge slide gate make it possible to empty the suction material into BigBags. This represents a dust free form of material discharge which is frequently required for toxic types of suction material. Additionally, the rear part of the taper can also be opened hydraulically, thus creating a discharge opening of 1000 mm at a height of 1.7 m. This makes it possible to dump the suction material into high containers - an enormous advantage, especially for urban applications. Another important practical advantage is the large loading platform under the collection container. Here, the operator can load at normal loading height approximately 120 m of flexible hoses and suction tools. A separate trailer for hoses is in most cases not required. The blowing device is as efficient as the one of BlowVac SL.
For example, gravel can easily be blown onto roofs with a height of 50 m. The only disadvantage compared to the SL: collection capacity is reduced due to the conical collection container. In practice this means that the BlowVac BigBag possesses approximately 10 m¦ of real collection capacity compared to 11.5 m³ of the SL.
Wieland Lufttechnik offers a large variety of customised solutions, especially for explosion protection requirements with all the standard options. This makes the BlowVac systems extremely comprehensive and versatile with a wide range of compact units for specific applications.