Brick Water, Sand, Cement & Limestone with Pinch Valves

A large company offering a diverse range of building products have been using a series of AKO Pinch Valves throughout their plant to transport dry silo mortar for the construction industry since 2003.

Material is blown up through the plant to it’s final destination of the ‘finished goods silos’. The Pinch Valves allow the company to control the flow of material and ensure the correct filling of the silos, by opening or closing, allowing material to pass through or to be redirected.

Application Details

The dry mortar consisting of sand, cement, limestone and brick water passing through the Pinch Valves is 20-30°C in temperature, blown through at a pressure of 2.7 Bar. The Pinch Valves are normally open, shutting off approximately 10 times per day with 6 Bar closing pressure.

Two Pinch Valves are used side by side in a “Y” formation for the filling of silos. One valve will be open, and the other will be closed. This allows one silo to be filled, and the other valve stops the material going to the other silo.

Each Pinch Valve is operated differently but the most used on this site is opened/closed every two minutes, and operates for 15 hours per day, 6 days per week. This equates to 450 cycles per day / 2700 cycles per week / 140,400 cycles per year.

pinch valve diverter system
pinch valve for building construction material
silo filling emptying application

Pinch Valves Performance

The building products supply company decided to use Pinch Valves within their plant because of their original design, and after successful trials with the product. The plant maintenance fitter told us that the company also use different types of valves throughout the plant for different processes, but the Pinch Valves work best for this process in question.

Sometimes, as well as replacing the rubber sleeve inside the Pinch Valve, the end flange connections need replacing also, due to wear. This is because of the abrasive material that the dry mortar is made up of. The company find it cheaper to replace the whole valve rather than just the sleeve and flanges, and this takes place approximately every 1-2 years.

VF125.03X.31.30LA
Pinch Valves used within this application: VF125.03X.31.30LA & VF050.03X.31.30LA

VF model, air operated, aluminium body, aluminium flanges PN10/16 with mild steel bushings, natural rubber sleeve.

VF050.03X.31.30LA

Solenoid valves and pressure switches are fitted to the Pinch Valves, as well as a pressure gauge as a visual indicator to show early signs of failure.

silo diverter system pinch valves
pinch valves for dry mortar
silo flow controlled with pinch valves
AKO Recommendations

AKO have advised the company to switch from aluminium flanges with mild steel bushings to flanges with stainless steel bushings (contact parts), which will significantly reduce wear and ensure the complete valve lasts even longer.

With regards to the line pressure of this application (2.7 Bar), and the closing pressure of 6 Bar, AKO have also advised that the closing pressure should be regulated down slightly. AKO Pinch Valves have a differential pressure of 2-2.5 Bar, which means anything higher than the differential pressure may cause the rubber sleeve to fail sooner. If exact pressure recommendations are adhered to, the Pinch Valve will last longer, and the user will be getting the most out of the product. To summarise, in this case we have advised for the closing pressure to be reduced to 5.2 Bar, which will still fully shut off the Pinch Valve, giving a tight seal. The smallest of changes can make all the difference.

As always, AKO recommends that one spare Sleeve per Pinch Valve is kept on site in stock at all times for scheduled maintenance. AKO also advise that mounting paste is used when installing a new Sleeve to the Pinch Valve.

Another recommendation was also suggested to this site, which was to make a note of the date with a marker pen on the valve body when the rubber sleeve was last replaced to keep on top of exactly how long they are lasting. In general, the company are replacing the sleeves in the Pinch Valves every 6-12 months.

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