Recently we run a survey over emailer and asked our users/clients & prospects about what’s the question that keeps on eating their head about screening, sieving & filtering technology & 82.7% of them had a common query.
The common query was “what to choose between a Rotary Sifter (centrifugal sifters) & Round Vibro Sifters & why”.
Well, to understand this we should know working principal & other main factors of both the type of Sieving machines.
The Rotary Sifter also known as Centrifugal Sifter works on Principal of Centrifugal force. The Rotary Sifter enables screening by pushing the product particles through the mesh using a screw conveyer or rotating paddles.
The round vibrating screens also knowns as gyratory sifter works on gyro principal. Eccentric weights are levied on top & bottom of shaft that rotates to generate 3-Dimensional movement –
Vibro sifters enables screening of products through the vibration generated by motor. Here there isn’t any involvement of rotating parts.
Below are the scenario-based points that will educate what to choose between Centrifugal Sifters & Round Vibro Separators & why!
If the product is of low bulk density & of lightweight Centrifugal Sifter would be the most suitable machine for the screening process.
The product that has lightweight & low bulk density if sieved in Round Vibro Separator will not pass through easily & would keep on traveling & jumping of the mesh screen as it would not get the required pressure & sieving process would not give required output.
If it is sieved in Centrifugal Sifter (Sivtek® Roto Sifter) it will be getting pressure from the centrifugal force generated through rotation of screw conveyer & this will help low bulk density products to travel through mesh screen area easily resulting into maximum efficiency while sieving process.
We had come across such a scenario where a client was using a conventional round separator for screening Silica Sand.
They wanted 3 ton/hour output & were able to achieve it with 3 units of round Vibro separator. One of our product experts visited their plant & suggested to test the screening process of Silica Sand with our Sivtek® Twin Roto Sifter as they might get 3ton/hour with the single unit of twin roto sifter. The trial was conducted & the result was exactly what our product expert had suggested. Now they have replaced 3 units of round Vibro separator with 1 unit of Twin Roto Sifter. Read full case study on Silica & Silicates.
To sieve & screen low bulk density & light-weighted products/applications such as Talc powder, Pigments, Silica Sand & more one should always prefer Centrifugal Sifters.
The products or applications that needs to be graded or classified into different sizes would be only fit to be graded with Round Vibro Separators – Sivtek® Vibro Separator & Super Sivtek® Separator as they can be built with 4 level
The products or applications that needs to be graded or classified into different sizes such as tea, minerals, etc. can be graded only with Round Vibro Separators as they can be customized with 4 layer of decks that can give 5 level of Gradation.
Watch video of tea being graded into different sizes with Sivtek® Vibro Separator.
Gradation is not possible with Centrifugal Sifters as it can only accommodate single mesh screen.
So, for the products/applications where gradation is required, round vibro separator would be the optimal option.
Few applications & products such as coffee, flours, soya lecithin powder, spices powder, etc. have high percentage of moisture & form lumps easily. To sieve or screen such products experts suggest installing Centrifugal sifters rather than round vibro sifters.
Main reason to choose Rotary sifters over round vibro sifters for products that form lumps easily is less product loss. While screening with centrifugal sifters the lumps breakdown due to rotation of screw conveyor that generates centrifugal force which in return enables zero product loss while in round sifter lumps stay over the mesh area & are thrown out from outlet which in return results into product loss.
Few applications & products such as metal powder, speciality chemical, flavours, etc. have very fine size particles & so to screen/sieve such products finest mesh is required.
For screening fine particle products Round Vibro Separator could be the only solution as our Super Sivtek® Separator & Sivtek® Vibro Separator can sieve up to 500# mesh while centrifugal sifter has a limit of sieving up to 100# mesh only.
For the applications such as pulp slurry, wastewater, etc. that has to separate solid from liquid Round Vibro separators are considered to be the most viable option.
While filtering liquid or slurries for separating solid contaminants/particles from liquid more area is required so that liquid can properly spread over that space. Fine mesh is also required as liquid can pass through easily & leave the solid part above the mesh. It is possible with round Vibro sifters only.
If we try to filter the liquid from Centrifugal sifters, chances achieving poor- & low-quality end products are high as during the separation process mixing of liquid & solid are more inside the chamber.
Watch the video of the separation of pulp from a backwater for understanding the point clearly.
Today many industries including food, pharmaceutical, minerals, chemical & more have to follow various act, standards & law that ensures safety norms for people & quality norms for products.
In industries like food & pharmaceutical, small contamination could severely affect the quality of the final product & that could be deleterious for end-user.
To avoid any such small contamination that could be either human-generated or airborne, centrifugal sifter is the best choice as it can provide a totally enclosed & dust-free environment while screening & sieving process if installed in the proper manner.
The reason it can provide a totally enclosed environment is it’s working principle. It works on centrifugal force & does not generate any vibration so rigid connection is possible at inlet & outlet, while in round Vibro separators work on vibration & only flexible connections are possible at inlet & outlet. Flexible connection increases the chances of leakage. For better understanding refer below image.
In industries like chemical & pigment, minerals, etc. during the manufacturing process hazardous substances are used & inhaling or coming in direct contact with such substances might be dangerous for operators & labors working over there. So, for sieving or screening, such materials totally enclosed system is recommended by industry experts.
Some industries also follow safety norms that allow only machines that generate noise up to standard DB. The industries & companies who follow such norms in accordance to safety laws should always consider Centrifugal Sifter as a first option as its noise level is less than 80DB which enables noise-free operation.