Gas bubbles, cast-iron grades and quiz pleasures

Click here if the newsletter is not shown correctly.

Control the flow with shut-off valves? Better not! What can happen? In a partly closed butterfly valve, there’s a crescent-shaped gap between the valve body and the disk. Here the medium can reach extreme gap velocities. The result: Cavitation! Gas bubbles can break particles off the valve body and the downstream pipeline. This leads to elutriation and leaks, even to holes in the valve body or also in the downstream pipeline. The picture on the right shows how seriously these continuously acting forces can damage a valve. To ensure the cavitation-free design of butterfly valves, factors such as the flow velocity, differential pressure and the flow rate must be taken into account – even if the shut-off valve is used for throttling for a short time only. Suitable control valves are the better choice and you can find them here.   Made from one casting! But which one? Cast iron is outstanding! It is corrosion-resistant and has excellent mechanical properties. But which grade of ductile iron is the right one for your application? Ductile iron grades such as GGG-40 (EN-GJS-400-15) or GGG-50 (EN-GJS-500-7) are mainly used in the manufacture of valves for water and wastewater applications. GGG-50 (EN-GJS-500-7) has a higher tensile strength and therefore is suitable for applications with a high static pressure. GGG-40 (EN-GJS-400-15) is resistant to deformation and clearly the better choice for applications with dynamic forces. GGG-40.3 (EN-GJS-400-18-LT) has a higher impact strength and is also suitable for heavy elongation. It can also be used in very low temperatures. Any questions regarding the selection of materials for your application? If so, please write to us. Quiz: How does our body lose the most water? Water is the most important resource in the world – for plants, animals and people. We are largely made up of water – around 60% for men, around 50% for women and for babies even more than 70%. Our body has no chemical reaction that would function without water. Water prevents our body from overheating and is the most vital material for endogenous substances. We lose around 2-3 litres of water every day and this water needs to be replaced.   Quiz question: How does our body lose the most water? a) Through our kidneys b) when we breathe c) through our skin? Click here to send us your answer in an email: marketing@vag-group.com Upcoming events 26 – 28 June 2018 1 – 7 July 2018 25 October 2018 11 – 12 October 2018 27 – 30 November 2018 Hydrovision Charlotte (North Carolina), USA ICOLD Vienna, Austria Aquarama Brabanthal Leuven, Belgium ANCOLD Melbourne, Australia Pollutec Lyon, France VAG GmbH Carl-Reuther-Strasse 1 68305 Mannheim / Germany Phone: +49 (621) 749-0 Fax: +49 (621) 749 2156 Managing Directors: Marcus Sander (President) Josh Horner Dr. Thomas Walter Local Court Mannheim HRB 9735 VAD-ID: DE811126215 www.vag-group.com info@vag-group.com

Click here to unsubscribe