Being universal in the field of application of special vehicles, vacuum loaders are gaining increasing popularity. But while in Europe the use of mobile “vacuum power” is a common practice, in Russia this type of rolling stock wasn’t very well-known until recently.
A tank or hopper with a tilting mechanism, a manipulator with a suction hose, a technological compartment with an autonomous power unit plus an automobile and truck chassis – this is what they call ‘vacuum loaders’. Initially such units appeared on the railway: in order, for example, to carefully collect the crushed stone between the sleepers when repairing the tracks. Today, this relatively new type of construction equipment is successfully used, in particular, in the excavation of underground engineering communications. In cases when the size of the construction site is limited or there is a risk of the equipment being damaged by the excavator bucket, the vacuum loader operates clearly and efficiently. Builders have to prepare just a small area, providing access to the necessary point. Suction air does not harm the electrical cables, high-voltage, fiber-optic and gas lines.
Another example: vacuum industrial cleaning during cement production allows returning most of the spilled cement to work, and cleaning silos with a vacuum excavator helps to avoid heavy manual labor. Collecting excess rubble from the site, removing spilled oil products or clearing production facilities and sites from dust and pollution (including hazardous substances) – all this can be done by a vacuum loader. It can also quickly make a recess for laying the pipe, a well for the pile, clean the clogged pipeline, dig a trench for the foundation.
The variety of applications of vacuum earthmoving equipment is almost unlimited. It works in the oil and gas sector, construction, telecommunications, at power plants and oil refineries.
The principle of the “vacuum power” is quite simple and at first glance resembles the work of a regular vacuum cleaner. The machine for excavating soil and other types of construction works uses a powerful suction airflow created by one or more fans or pumps. Through the sleeve, air along with the material gets inside the machine, where it passes the collection chamber and the filter system and then is released back into the atmosphere. Sometimes the manufacturer provides an on-board compressor for the automatic cleaning of filters. The high performance of the unit ensures a high speed of the airflow in the suction hose (sometimes more than 100 m / s). The hose mounted on a cranked or telescopic boom with hydraulic drive can be moved in several angles, which provides high accuracy of work. The sleeve is elongated with the help of nozzles, so the material can be transported horizontally up to 200 m, and vertically up to 60 m. If necessary, the extracted material can be used to backfill the excavation site. During unloading, the material collection chamber is tilted like a usual bucket. Some vacuum systems have common features with vacuum cleaner vehicles or bulk tippers, special tanks for transportation of granular materials.
A wide range of “industrial vacuum cleaners” allows choosing a machine within almost any budget.
Compact trailed models can be transported with a small car. The largest of them are mounted on a truck chassis and have different options. The search for a suitable vacuum loader, as well as the selection of any other construction equipment, begins with a clear definition of the amount and type of work to be performed. It is also necessary to determine the maximum particle size and the nature of the soil. For example, such solutions are not very suitable for working with hard and frozen soils. Under such conditions, other technologies are used.
The type of vacuum pump is also important. Centrifugal pumps are used in powerful systems, and piston ones are used in small installations. However, not so many manufacturers in the market offer the models that are able to perform really serious tasks. A lot of machines, especially in the US market, have a low performance and simple mechanisms.
Basically, such “excavators” work in the city economy.
If we talk about the market of vacuum loaders on the automobile chassis, at present its lion’s share belongs to European manufacturers. German company MTS, which has been known for its developments in this field for more than 20 years, produces two series of installations on the automobile chassis – Dino and Mega-Vac. The heavier Mega-Vac models are equipped with four fan pumps, which create a vacuum of up to 62 MPa, while their capacity exceeds 40,000 m3 / h. The collected material is placed into a 9 cylinder container through a sleeve with a diameter of 250 mm. The delivery distance of the material reaches 200 m, and the suction depth is 30 m. As an option, the hydrostatic drive of the machine with remote control is available. It allows the machine to move simultaneously with the material intake.
The highlight of the design – “thin flow technology” is characterized by the fact that the amount of transported material comparative to the air volume is negligible, which provides high separation due to gravitational forces, minimal load on the filters and thereby increases overall productivity. The main element of the installation is a fan with a three-stage power adjustment. The installation can have a single or twin fan, as well as a combination of them or two twin fans. The hard collecting hopper includes a central prefabricated chamber with special wear protection and a fine filter system. The unloading is carried out by way of lateral tilting with the help of a hydraulic drive.