Sanitary Mixer Design: Factors To Improve Productivity And Decrease Costs

By Mark Franco, President And CEO, MXD Process

It’s time to come clean; sanitary mixer impeller design can be very difficult. It seems the acceptance criteria are so subjective in each segment of the food industry that coming up with a standard is next to impossible. If you are reading this, I’m sure you have had the experience of looking at a piece of equipment and saying, “Why in the world did they build it this way? It’s going to take me hours to clean that!” This article aims to provide a few pointers for purchasing food-grade mixing machines, including ways identify the critical issues of mixing equipment and suggestions to narrow down the design and ensure a smooth cleaning experience.

So, what is the true cost of non-cleanable equipment? If sanitary mixer design is not considered at the design stage, it can be very costly in the production stage. You think you bought a piece of equipment that is clean-in-place (CIP), but you have to spend two hours each shift cleaning the equipment to prepare for next day’s production. This can lead to tens of thousands of dollars of lost production time and cost. Additionally, you will have to invest earlier in capital equipment and additional square footage as your facility grows.

Designing For Cleanability From The Start 

Let’s say a food manufacturer is looking to start up a new sanitary line and within the project specifications is a folding impeller for mixing. This makes sense in some aspects of the mixing process as the tanks of this particular manufacturer can only use a small, sanitary tri-clamp mounting flange to attach the agitator. The fluid being produced exhibits a medium viscosity, requiring a larger impeller. The folding impeller is excellent for getting a large impeller into a small opening and has its place in the annals of impeller history. However, there is a significant downside. It contains a multitude of nooks and crevices that encourage bacterial growth. Even the best CIP system will fail to adequately clean a small, folding impeller.

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