... DN: 50-700mm(2-28") CST42Y Automatic Re-Circulating Control Valve (reflux valve) is installed at the outlet of centrifugal pump to provide ... the outlet of station pumpsMaterial:Material quality: titanium, nickel, zirconium, Hastelloy, Monel, 316,310,304,WC6 and etc. Automatic Recirculation Control Valve (Return Valve)