The maintenance-free RSK swing check valves (photo) offer a high functional reliability because a tight shut-off is ensured by a rubber-lined valve disc without rotating parts and without extensions through the body wall. Because all wetted parts are rubber-lined, they are highly resistant to corrosion and abrasion, such as in fluegas-cleaning systems. The swing check valves are fluid-controlled, which means their functionality cannot be manipulated from the outside. In low flowrates — that may occur when operating variable speed pumps — the valve disc remains stable in its position and does not tend to chatter. With their streamlined design, the flow resistance of these valves is up to 45% below that of alternative check-valve types. The valve can be mounted in either a horizontal or a vertical position. The bodies made of nodular cast iron are available in nominal sizes 25 to 300 and designed for a nominal pressure of 16 bars. — Sisto Armaturen S.A., Echternach, Luxemburg