Through the structure of two-seater regulating valve body parts: There are two valve seats in the valve body, the spool, the spool for the double guide. The valve produced in the 1940s, 60s domestic joint design, is the level of the sixties product. It uses the following features: (1) As the fluid pressure on the two spools, unbalanced forces cancel each other a lot, thus allowing a large pressure drop. This kind of structure that can offset many unbalanced forces each other is a balanced structure. (2) At the time of closing, due to the machining error, the two sealing surfaces of the valve core and the valve seat can not be sealed at the same time. Therefore, the leakage amount is ten times to one hundred times larger than that of the single seat valve. Meanwhile, the amount of leakage during the temperature change Will increase, which is its outstanding shortcomings, it can not be used in the process of small leaks. (3) due to the complexity of the valve body flow path, coupled with the upper and lower guide easy to be stuck by the solid particles, not suitable for high viscosity, suspension, solid particles and other easy to precipitate, easy to clog occasion! (4) Too heavy.