Free-valves centric butterfly valve adopt center lined principle to design, it uses the flexibility rubber seat, could easily achieve zero leakage and bi-directional sealing, it also can be used as regulation and shut-off device to deal with corrosive, non-corrosive gases, liquids in pipelines . Features 1.Bi-directional sealing, throttling operation and shut-off function. 2.Fully rubber lined body, with lined rubber extending up to the flange contact face, resilient seat. 3.The choice of disc and seat materials to suit working conditions and medium. 4.With self lubricated ptfe lined bearing designing , life cycles up to ten thousand times cycles . Technical specifications 1)size rangenps2~nps64, 2)pressure rangepn6~pn16, class150 3)body materialcarbon steel, stainless steel, copper alloy 4) sealing materialrubber or ptfe 5) body typewafer b ody type, lug type or flange type 6) working temp erature:120 7) operating methodworm gear, electric, pneumatic . 8) pressure test:gb/t13927; api598 9) face to face: gb/t12221; api609, en 558 Applicable Free-valves centric butterfly valve could easily achieve bi-directional sealing, therefore is a widely applied valve in oilfield, agriculture, power plant condensates waterworks, water treatment, seawater, exhaust, flue gas.Because of rubber lined body materials, it is usually used in low pressure lines.