Pinch valves reliably control cement slurry and glass-fibre reinforced concrete

A company specialising in garden furniture and planters made out of cement slurry and glass-fibre reinforced concrete is successfully using DN 25 pinch valves from the VMC series with internal thread connections and anti-abrasive sleeves made out of natural rubber.

The concrete is pushed through a special spray nozzle at high pressure during the production of the garden furniture and planters. At the same time, shredded glass fibres are blown into the sprayed concrete to strengthen the surface of the product. The product flows have been controlled by the installed pinch valves from AKO Armaturen for a number of years.

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This task was previously carried out using ball valves but the moving parts already displayed signs of wear after a short period of time and they had to be replaced. Due to the highly abrasive sand particles (grain sizes: 0.6 mm – 1.0 mm / 0.04 line – 0.39 line), lubricant deposits formed very quickly on the closing mechanism for the ball valves which meant they did not close tightly. The water contained in the medium was thus able to pass though the valve in a closed state. This caused the medium immediately behind the valve to dry into a semi-solid state. Under these circumstances, it was possible for the semi-hardened mass to block the spray head and burst the transport hose when the ball valve was opened. “The consequences are easy to image”, said a representative from the company.

„We were pleasantly surprised by the service life of the sleeves made out of natural rubber despite the difficult conditions – we are still using the first sleeves to be installed to this date! Simply a great product!“

After installing the pinch valves from AKO Armaturen as an alternative to the faulty ball valves and using a closing timer to configure the valve to allow a continuous flow to the spray nozzle (the pump supplying the material works using pulses), it was possible to reduce downtimes and maintenance work to a minimum.

If a sleeve needs to be replaced, it does not result in long downtimes. It can be replaced quickly, easily and without any problems on-site by the company’s own employees. It is not necessary to completely replace the entire pinch valve.