A northwest England cereal factory uses these sanitary pumps to reduce waste during the coating process.
by David Webber
Sanitary rotary lobe pump used in the coating process
A rotary lobe pump was selected as a perfect fit. The pump is certified to European Hygienic Engineering and Design Group’s (EHEDG) sanitary standards. Founded in 1989, the EHEDG is a consortium of equipment manufacturers, food industries, research institutes and public health authorities that promote hygiene during the processing and packing of food products.

The group provides the highest standards across Europe. Similarly in the U.S., these pumps comply with 3A hygienic standards.

These sanitary pumps are designed to handle an array of food products and ingredients. Following months of tests and trial runs on selected production lines, using different coatings with a range of consistencies and spray rates, the cereal maker’s food engineers decided on hygienic rotary lobe pumps.

These pumps were the ideal solution for making the breakfast cereals responsibly. The cereal engineers, some of whom have been with the company for more than 20 years, put the pump through extreme and normal production conditions. They determined that the pump could be relied on to deliver a predictable spray to coat the different grains.

Every step in manufacturing the cereal is carefully monitored for quality. Since it is intended for human consumption, sanitation is essential. The chosen pumps contained hygienic steel, which can be thoroughly cleaned and sterilized and can operate in temperature ranges from -40 C to 180 C.

A lubricated shaft, bearing and gear assemblies ensure a long product life, while fully interchangeable and accessible rotors avoid the need for re-timing and allow for easy maintenance.

While many types of pumps are available, their effect on product quality can be disastrous if the wrong type is installed in a process. The solution to successfully handling the cereal products came from a technology that has been in service worldwide for more than 30 years.

Rotary lobe pumps are designed so the fluid, or product, fills the expanding inlet cavity and then is displaced by a decreasing cavity on the outlet side. This action moves the fluid. Next, two counter rotors provide gentle movement with minimal fluid or product damage from the pumping action. The speed and power of the drive motor can be adjusted to the flow rate desired for the manufacturing process.

In addition to the benefit of the gentle pumping action, rotary lobe pumps are designed to handle product with the viscosity of up to 1 million centipoise. For example, water has a constant viscosity of 1 centipoise. In contrast, mayonnaise and tomato sauce have a viscosity of 20,000 centipoise and are referred to as shear thinning.

The term shear refers to the application of force, such as pumping action, to the product, and the transformation from being thick like honey to a thinner viscosity. As the product is pumped, it begins to shear, or flow more easily.
The engineers determined that the sanitary rotary lobe pumps met the critical threshold for pumping delicate, viscous fluids and products that contain solids in suspension in a reliable and consistent manner.

The Results
The cereal production engineers found the output flow from the rotary lobe pumps smooth, steady and pulsation-free. The gentle pumping did not break down the liquids and ingredients.

The resulting decision was to install dozens of the rotary lobe pumps on its production lines. With the pumps installed, consistent coatings and production uptime are virtually assured.

This means little of the costly coatings that make cereals so appealing to consumers are wasted. The cereals pass under the fine spray delivered by the efficient pumps.