Fruit preparations and finished sauces are the kind of product that punishes the wrong pump. They can be thick enough to resist flow, they contain soft pieces that a high speed impeller will destroy, and they often have to be drawn from a vessel where the level is falling and the suction is unreliable. A twin screw pump is frequently the right answer because it is a positive displacement pump that moves product at low speed, with low shear and with no need for a flooded suction.
Working principle and why it is gentle
Two intermeshing screws rotate inside a close fitting casing and form closed cavities that travel from the suction end to the discharge end. The product is carried rather than thrown, so the pieces keep their shape and the product structure is preserved. Because the screws are driven and do not rely on centrifugal force, the pump generates a nearly constant flow at a given speed, which makes it easy to meter product into a filler, and it can self prime from a suction lift that a centrifugal pump could not manage.
Where it fits in a sauce or fruit line
Typical duties are transfer from a cooker or mixing vessel to a filling machine, unloading from a road tanker, and feeding a homogeniser or a deaerator where a steady inlet pressure is required. The pump tolerates the viscosity change that happens when a warm product cools in the line, which is a common source of trouble on this duty.
Hygienic construction and cleaning
The pump is built in 316L stainless steel with a controlled finish, fully drainable and free of crevices so that it can be included in a CIP circuit. Where the product is pumped at high temperature, the pump can be supplied in a jacket heated version so that the product does not set in the casing during a stop. Shaft sealing is selected from the duty: single mechanical seal for ordinary food service, and double seals with barrier fluid or a seal-less magnetic drive where leakage of product or ingress of cleaning solution must be excluded.
Ordering information
To select the correct pump send us the product and its viscosity at pumping temperature, the maximum particle or fruit piece size, the required flow rate, the discharge pressure and pipe length, the suction condition, the pumping temperature, the cleaning chemistry and the electrical supply. Rotor profile, pitch and drive are then confirmed against the duty. Material certificates to EN 10204 3.1 and a performance test record are supplied with each pump.
