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Resolving the issues of solids in pumped chocolate

07 October 2017

A chocolate producer needed to add solids handling functionality when pumping chocolate. Food Processing finds out more. 

The pumps in question needed to be able to handle an already troublesome medium – chocolate – to allow for the addition of a variety of different solid inclusions, such as nuts and raisins, to the chocolate mix.

Chocolate is renowned for being difficult to transfer, needing one of the most difficult fluids to transfer correctly. It will solidify when cool, so it has to be kept warm, not only as it moves along the pipelines, but also through the pump. 

Another challenge is that chocolate is shear sensitive. The cocoa butter and cocoa solids can easily separate if moved too fast. Chocolate will also react the same way if the discharge pressure is anywhere over 100psi, so correct configuration of the discharge lines is also important.
The company approached Triark Pumps for a solution. Its engineers initially considered using an air operated double diaphragm (AODD) pump, which is often the most successful pump type for chocolate-based applications. However, the lack of a localised compressed air supply meant that a different approach was required in this application.

Limited choices
Unfortunately choices were limited given the need for an electrically operated pump that could run slow (due to the shear-sensitive nature of chocolate), handle solids (nuts and raisins) and be heated so that the chocolate wouldn’t cool during the normal running cycle or when the system stopped.

Positive displacement pumps were considered to offer the best solution in this application. The mechanical movement of fluid by gears can offer benefits in applications handling viscous fluids that a centrifugal pump would be unable to handle. The output is also more very controllable.

Having carried out extensive ‘pre-selection’ research before discussing possible options with a number of its key suppliers, Triark Pumps identified several alternatives from manufacturers such as Alfa Laval, Grundfos and Desmi.

Thanks to information gained by David Rozée, Triark’s managing director, during a visit to India where he witnessed Desmi pumps in operation at a manufacturer of semi-finished cocoa mass, the most appropriate solution for this application was determined.

Triark supplied two Desmi Rotan 2in positive displacement internal gear pumps, comprising cast iron casing and rotor, mild steel shafts, bronze internal bearings, front and rear heating jackets, packed gland seal and secondary lip seal. IP55, EFF1 gear motor and mounted on a fabricated ‘top hat’ style stainless steel base plate, with a stainless-steel coupling guard.

Commenting on the application, Rozée said: “Desmi has built an enviable reputation in the manufacture of pumps for the food and drink sector, so not only did the eventual selection provide a quality solution which to date has been running without issue for this customer, it also provided the most cost effective option, enabling us to tick every box on the original brief”. 

A technical demonstration can be viewed at:

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