Bellows valve is a kind of pressure balance type control valve, the valve structure is compact, the fluid channel in an s-shaped streamlined, small pressure drop loss, large flow, wide adjustable range. Cover adopt wave tube lines on the sealing structure, can eliminate process medium movement clearance from the stem to the possibility of a leak, it is one of the significant characteristics of bellows seal valve. Because of the corrugated pipe deformation element itself and its aging resistance, regulator completely overcome the packing seal valve usually packing aging and temperature sensitive weaknesses. Secondly, using the corrugated tube packing double sealing structure, better safety and reliability. Therefore, it is highly toxic, corrosive, radioactive and other special medium rare is widely used in automatic control system. Regulator with more spring loaded diaphragm actuator, its compact structure, big output force. Leakage: metal seat: standard ANSIBl6.104 Ⅵ level, less than the rated 0.5 ℅ of Cv; Ptfe seat: standard meet ANSIBl6.104 VI level, less than 10-7 return difference of Cv rating: 5 ℅ (without the locator); 3 ℅ (with locator) linear: plus or minus 11 ℅ (without the locator); Plus or minus 3 ℅ (with locator) note: v-type ptfe packing with a standard.