Published December 30, 2011 20:48US PATENT ISSUED FOR PRODUCT DENSIFICATION UNIT (PDU)
Extru-Tech, Inc. was issued U.S. Patent No. 5,622,744 on April 22, 1997 for its versatile Product Densification Unit (PDU).
The PDU is used in conjunction with a conventional extrusion cooking system to produce high quality sinking aquatic feeds and animal feeds. Feed ingredients are gelatinized and expanded using a cooking extruder to form an intermediate product which is immediately introduced into the PDU. The PDU is a specially designed low shear extruder which is adapted to densify and shape the intermediate product into a final feed product which is dense enough to sink in water and stable enough to retain its form for a considerable period of time while either submerged in water or exposed to weather.
The PDU provides the advantage of allowing manufacturers to produce high quality sinking or slow sinking aquatic feeds and animal feeds at higher capacity rates compared to production systems using a stand alone cooking extruder. Since the PDU is a low shear extruder that is used to densify a gelatinized intermediate product, a consistent flow of sinking products and dense feeds will be produced without the worry of possible product expansion which will cause a lighter density product and floating products when immersed in water.
The PDU is equipped with a variable speed drive which allows speed adjustment of the extruder shaft and provides the versatility to produce sinking and slow sinking products.