The In-Line Tru-Balance Sifter works like our multi-sieve gravity flow sifters except that it operates under the pneumatic conveying line (pressure or vacuum) conditions. The product is gently sieved without being forced through the screens by the conveying air and without any mechanical beaters or impellers. The air is “filtered” separate from the product to insure that no oversize impurities can bypass the protection of the sifter.

As the product is conveyed into the sifter, it enters an expansion chamber where its velocity decelerates and naturally begins to separate from the conveying air. The product is directed to the sieves and begins to sift through the screens.

As the product is gently sieved, it falls on a stainless steel pan that gathers and directs the sieved product to two side channels - one on each side of the sieve frames. Product and oversize not able to pass through the screen is conveyed on to the next sieves until all fines are removed. The oversized impurities are directed to a sealed tailings container.

The product being screened forms a layer on the sifting screens that creates a resistance to the flow of air through the screens. Naturally, the conveying air seeks the path of least resistance, which is found through the air bypass screen positioned directly above sieve #1. Typically, the air bypass screen is covered with the same screen mesh as is used for sieving the product but acts more like an air filter than a sieve. The filtering effect of the air bypass arrangement actually allows the air pressure to equalize on both sides of the sifting screens so that no pressure differential would force product through the sifting screen.

The chamber above the air bypass screen is connected with the two side channels common to the lower intermediate sieve frames. The "filtered" low velocity conveying air travels down these side channels, re-entraining the sifted product and then conveying the product out of the sifter.

To protect the sifter housing from over pressure conditions (or low pressure conditions for vacuum systems) the sifter is equipped with an appropriate spring-loaded relief valve.

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