I. Description

　　 ZJ Series (precise) pneumatic adjusting valve is small, light, precise and high-efficiency. It is developed on the basis of the world's mature design technology, rich processing experience and advanced foreign structure, and reaches the advanced standard of the 1980s. The valve is also a new-generation product in conformity to the IEC standards.

　　Pneumatic adjusting valve is one of the most widely used and most important products in the controllers of the production control system. And ZJHP pneumatic single-seat valve and ZJHM pneumatic sleeve valve are the universal products that are most frequently used in ZJ series. They are applicable for the control system of the equipment with general fluid medium and technical conditions.

　　In addition to the common advantages of all pneumatic instruments, ZJ series features reliable action property, precise flow rate, wide adjustable range, stable operation and little leakage. Hence the high quality control in various industrial sections.

II. Operational Theory and Structure

　　ZJHP Pneumatic Single-Seat Adjusting Valve is composed by ZHA(B) pneumatic multi-spring membrane actuating mechanism and VJP low flow resistance through single-seat valve.

　　ZJHM Pneumatic Sleeve Adjusting Valve is composed by ZHA(B) pneumatic multi-spring membrane actuating mechanism and VJM low flow resistance through single-seat valve.

　　After the external pneumatic signal is input into the membrane chamber, the pressure acts on the membrane and generates thrust force, which compresses the spring unit and enables the pushing bar to move. The pushing bar then drives the valve rod, and the rod makes the valve core start to work until the thrust force is equal to the balanced force generated from the compression of the spring unit, and the rod is stabilized at a certain distance. Therefore, the valve core distance is proportional to the input pneumatic signal.

　　The operation modes of the pneumatic multi-spring membrane actuating mechanism falls into two categories: proportional mode and inversely proportional mode. Proportional mode means the pushing bar moves towards the opposite direction of the membrane chamber when the signal pressure increases, and the model adopting this mode is called ZHA. Inversely proportional mode means the pushing bar moves towards the direction of the membrane chamber when the signal pressure increases, and the model adopting this mode is called ZHB.

　　Valve Body, Valve Cap: HT200;ZG230-450
　　ZG1Cr18Ni9

　　Internal Components: 1Cr18Ni9 (Please contact the us if special or hardened materials are needed.)

　　Stuffing Materials: Teflon, Soft Blacklead

　　ZJHP and ZJHM pneumatic adjusting valves are grouped into two types: pneumatically closing type and pneumatically opening type. The former one is composed by proportional actuating mechanism and valve, and the valve turns from completely open to completely close when the signal pressure changes from lower limit to upper limit; while the latter is composed by inversely proportional actuating mechanism and valve, and the valve turns from completely close to completely open when the signal pressure changes from lower limit to upper limit.

　　Pneumatic Multi-Spring Membrane Actuating Mechanism features low height, light weight and convenient installation and check. The system consists of the membrane, compression spring, tray, pushing bar, bracket, bearing and membrane cap etc. The deep basin shaped rubber piece adopts quality material, enabling it to function normally in a temperature range of -40℃ to +85℃ with little variation of effective area. The compression spring unit has multiple springs to reduce the height. The guidance surface of the pushing bar is precisely processed, hard and smooth, allowing the reduction of return difference and the improvement of sealing performance. The inversely proportional actuating mechanism adopts the O-ring structure, and is matched with the pushing bar and bearing sleeve, simple and reliable. Through accurate design and precise process, the mechanism abandons the adjusting complex of compression springs so that it can be installed at one step without the necessity of amendment. The pushing bar and the valve rod are connected with split nut and can be easily assembled or disassembled.

　　The structure of low flow resistance through single-seat and sleeve valves is simple and compact, and their flow coefficient is quite high. The valve adopts the single-seat bottomless top guiding design, small, light, fluent and high-efficiency. The connection of valve body and pipes is in the pattern of male and female flange to match various rated pressures. The valve cap has two models, namely, normal model and high-temperature model, to get adapt to various work temperatures. Specific windows are precisely processed in the sleeve to accurately control the flow rate within the IEC and national standards. The standard stuffing material is Teflon moulding filling, and soft blacklead is also available if necessary.