The Process of Milling Flour

The flour milling process has evolved from wheat being ground between two large stone wheels (although this process does still occur in a few mills). In a roller mill the practice centres around separating the three components of a wheat seed – the white endosperm, the outer bran layers and the wheat germ. These are each made up of different materials and when separated and milled in isolation the miller can produce flours that are finer and therefore better suited for today’s uses.

A local flour milling company is responsible for it’s group’s biggest flour output – over 200,000 tons of wheat is milled annually, resulting in 150,000 tons of flour. This is mainly for bread production, but is also for biscuit manufacturers and other specialist areas.

The transportation of flour around the mill and into the desired bins and packing bags is an important task, one of which is controlled using valves.

How the Valves Assist with the Transportation of Flour

The valves are part of the blow line which feeds the holding bins for the flour packers. Each valve is normally closed until the engineers on site select the bin they are packing from.
valves for flour packing
To start the flour blowing through to the holding bin above the packers, the engineer needs to select Bin 1 (for example) on the control panel, which directs the system to automatically open a valve.
The mill mills the flour, which goes into Bin 1. When Bin 1 is selected, the flour travels through the blow line at 4 BAR and blows through a turbo sifter. The flour then travels along the blow line through the air operated Pinch Valve where it drops through into the bins above the packers, and then into bags.
Pinch Valve used within this application: VF125.02X.35.30LA

VF model, air operated, aluminium body, aluminium flanges PN10/16 with stainless steel bushing contact parts, white food quality natural rubber sleeve.

A small amount of air is used to close the valve, and each valve is opened/closed a few times per day.

The Valve that Just Keeps on Giving!

AKO UK pneumatic Pinch Valves are known for their longevity, providing a sufficient, reliable service in many applications. The term ‘fit and forget’ is often used when describing how a Pinch Valve by AKO UK performs – much like this flour mill which has not needed to replace the valves or any spare parts in years. The mill have some replacement food grade rubber sleeves in stock just in case of failures, but the valves are continuing to perform with excellence.
In another instance, AKO UK have supplied air operated Pinch Valves for flour at a bakery site, assisting with the application by preventing unauthorised flour filling or over-pressure events, whilst filling the silo. Read our case study for more information including the amazing length of time it has taken for a Pinch Valve to need to be re-sleeved.
How to Avoid Clogging in Flour Bins
An engineer at this flour packing mill told us that they recently took one of the Pinch Valves out of line because the flour wasn’t getting to where it needed. Lumps of flour had started to accumulate in one of the bins. They thought it could have been a problem with a Pinch Valve but upon inspection, they couldn’t find anything wrong and the valve was as it should be.
The build up of flour in the bin could have been caused by a number of things, one of which could be a change in temperature, causing the flour to turn moist and clumpy, thus restricting the flow.
To solve this issue, AKO UK supplied aerator pads to prevent the build up of clogged flour in the form of caking, bridging and rat-holing. The aerator pads are fitted onto the inside of a bin, silo or hopper and pulse with a vibrating motion to agitate the sides of the vessel. This agitation releases any media that is stuck on the bin walls or clogging at the exit, freeing up the flow.
Read more about how aerator pads work and some case studies where they have helped in a number of different industries.

Experts in Valves for Flour

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