Six-cylinder without pulsation

Dirk Mucha

The pumping action of a conventional peristaltic pump is based on the progressive contractions of a hose in order to convey the product. The hose is compressed two or three times per revolution, depending on this design.

The conveying cavities of the MAP take the same form as the concentrically balanced rotor. The revolving helical rotor compresses the hoses inserted in the stator into sections and moves each progressive cavity from the suction side to the pressure side. The rotor of the MAP only slips over the hoses once per revolution. The frequency and type of compressing action have a decisive impact on the service life of the hoses. A hose service life of more than 3000 operating hours is possible using the MAP. In conventional hose pumps, the hose stress starts immediately upon insertion into the pump. The bent fitting position causes tensile stress and compressive strain in the hose structure. In contrast, the hoses of the MAP are arranged axially and are free from all external constraints in the pump. A further advantage with regard to the hose service life is the substantially lower sliding velocity of the rotor on the hoses. Thanks to the reduction of over 50% in the rotor diameter, the sliding velocity has been more than halved.

By combining the pulsation-free perfor-mance of the progressive cavity pump with the seal-less hose pump technology, this pump offers a number of new possibilities for the user, especially for metering and mixing. Up to six hoses are enclosed in one casing. These hoses can be brought together in a single manifold on both the suction and pressure sides or provided with separate connections for each hose. The almost pulsation-free performance of the MAP is a result of the flow of the individual hoses being combined at the discharge. Moreover the use of multiple hoses makes it possible to convey up to six different liquids in one pump.

The MAP is suitable for metering, mixing and permanently transferring almost all products in practically every branch of industry, and especially for handling products containing solids, abrasives, adhesives or shear-sensitive, viscous and toxic products.

Bayer AG in Leverkusen solved a difficult problem by using the MAP multiple-hose, axial-flow, peristaltic pump. Bayer experienced difficulties in pumping a highly abrasive suspension to a conveyor belt. Tests conducted with other pump types were unsuccessful, either due to the excessive wear caused by a DS content of 30 to 35 % or because of undesirable physical properties such as poor efficiencies or pulsation.

The MAP is resistant to abrasive liquids as no mechanical parts or shaft seals are in contact with the product. These properties are theoretically common to all hose pumps, but the pulsations arising from this pump type lead to problems which can only partially be solved by the use of pulsation dampeners. The degree of dampening is possibly too low, the dampener cannot adapt to new application conditions, the required space for installation is not available or the expense for the alterations is too high.

When the MAP is used, the individual pulsations of the six feed hoses are interconnected to ensure an almost pulsation-free output. This effect is comparable to the quiet running of a six-cylinder engine in comparison with a single-cylinder engine. With regard to the Bayer application, the low pulsation flow permits a Coriolis-type, mass flow meter to be installed in the pressure pipe.

Seepex

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Further information cpp-258