Some people may at some point use double seal valves instead of shut-off valves, but valve manufacturers do not recommend this. The reason why the valve manufacturer does not support the use of double seal valve instead of the shut-off valve is because the advantages of two-seater valve spool is its force balance structure allows a larger pressure drop, but it has two sealing surface can not be a good contact, easy to cause The big disadvantage is that if it is used artificially or forcefully to cut off the occasion, the effect is definitely not ideal and it is not desirable to make improvements halfway.