Our specialists often face the problem of discrepancies in the meaning of technical terms, as well as misunderstandings in the meaning of the words “bunker” and “silo”. That is why it seems to be necessary to outline the differences of these types of containers for storing bulk stock.
Both silos and bunkers are storage installations with top filling and with bottom discharging (unloading), meant for storage and/or transshipment of bulk products and materials. Silos are cylindrical in shape, bunkers are either cylindrical or rectangular. The bottom is either conical or flat depending on construction. In case of flat bottom the complete discharge is carried out with the help of cleanup screw.
- the height of the vertical side of a metal silo is more than 1.5 times longer than the diameter. This is applicable to silos which diameter does not exceed 18 m (the ratio of the vertical height to the diameter for bigger silos may be less than 1.5).
- The height of the vertical side of a metal bunker (cylinder or rectangular block) does not exceed 1.5 of the minimum size in the plan (diameter or the smaller side of the rectangular dimension).
The second basic difference between a silo and a bunker is to be seen in the following: the plane of break, led from the bottom point of the vertical side (through the cross-over of the hopper and the vertical wall) crosses the free surface of the bulk material in the bunker in case of extreme fill-up.
Thus, a silo is a cylindrical container, higher and narrower compared to a bunker.
Please, mind that the above mentioned differences in the terms “silos” and “bunkers” are considered classical. In practice the names of the storage tanks for bulk stock are often mixed. It is sometimes seen in the design documents that a “metal silo” for storing grain has the height twice less than its diameter, or sometimes the term “bunker” implies a small silo-hopper used for loading grain to vehicles. That is why we advise to pay attention to the functional characteristics of the ordered equipment.
The sphere of application of metal silos:
The most popular types of storage containers for bulk stock, mass produced by “RussianTankWorks”, are as follows:
- A bin (a silo for cement) and bulk construction materials;
- A silo for grain / flour / food products for long-term storage;
- A silo for grain / flour / food products for short-term storage.
These frameworks differ in material (as regards the requirements for storage of the exact product), and in construction details (a flat bottom is used for long-term storage, conical shape of the bottom is for short-term warehousing and transshipment).
Metal silos and bunkers are used in industrial and agricultural sectors for loading, warehousing and metered (dosed) discharge of all kinds of bulk materials and products, both organic and non-organic.
Silos and bunkers for organic, especially food products (for flour, grain, feedstuff hoppers) are made of high-quality galvanized steel. Ferrous metal-roll is allowed for production of silos and bunkers for cement, calcium sulphate, dust, sand, silt, lime carbonate (09Г2С,Ст3сп5).
The scheme and operation procedures of the storage tanks for bulk products:
A metal silo and a cylindrical storage hopper consist of a vertical cylindrical shell. Depending on the type of silo the roof is made either conical or flat. Silos for short-term storage of grain / flour / food products have conical bottom, installed on supporting frame, which height depends on the way of discharge of the bulk stock. The bottom of silos for long-term storage of grain / flour / food products is made flat, providing the cleanup screw for the discharge purposes.
The roof of silos and metal bunkers bears inspection manway giving the access to the inside for providing service. A silo is also equipped with stairways, shell walkways and the deck on the roof with a fence.
“RussianTankWorks” provides inspection sensors for top-level, bottom and medium positioning for its silos and bunkers. After installation of the storage tanks for bulk products the data from the sensor is transmitted to the control room or to the shut-off valves.
For the sake of constant feed and discharge of the product a vibrating device is provided at the lower part of the silo.
Industrial manufacturing of silos and bunkers:
Silos and bunkers production facility is equipped with automated and auto-manual welding equipment Lincoln Electric and modern equipment for metal-roll preparation (sheet metal leveling machines, edge processing equipment, mechanical processing devices). This ensures high quality of the welding joints, exact geometric parameters of the finished unit and operational efficiency of production.
The metal frameworks of large silos, made with the coiling method, are produced on a special welding skid, that allows to weld the primary and the second welding joint automatically. Coiling makes the period of large silo’s installation 3-4 times shorter as a result of reducing the scope of welding procedures at the construction site by 80 %. This technique also ensures the highest quality of the welding joints.
The warranty period for our silos and bunkers is equal to 18 months from the start-up or 24 months from the date of delivery from the plant.
Installation of metal silos and bunkers:
On the Customer’s request the metal frameworks of silos may be installed by our construction and assembling team, that consists of highly-skilled specialists, that has the full set of permission documents and rich experience in construction and assembling.
While installing large silos produced by coiling method, the coils, brought to the construction site, are put in the vertical position and unrolled along the perimeter of the circle foundation, thus making the full-circle wall.
Installation of sectional parts of the silos’ framework may be carried out with special pin-connected joints with the use of polymer tight joints and special conical washers. This method allows to keep the corrosion-preventing coating safe and to reduce the cost of installation to minimum.
We recommend to order silos and bunkers on turnkey basis from one and the same contractor. In this case we bear the full responsibility for Your equipment from the stage of the engineering design to start-up. We will be able to reduce the cost of materials, delivery logistics expenses, as well as to install our metal frameworks quickly and effectively, providing the excellent documentation procedur