... Diameter DN: 50-700mm(2-28") CST42Y Automatic Re-Circulating Control Valve (reflux valve) is installed at the outlet of centrifugal ... can make a few mediums recycle in pumps under load motion, ensure the minimum flow for pumps safety operation and maintain ... , Hastelloy, Monel, 316,310,304,WC6 and etc. Automatic Recirculation Control Valve (Return Valve)