The Y (X) KD743H 0.5 second hydraulic control quick closing valve is mainly installed in high safety level systems such as the steam extraction pipeline of the steam turbine and the intake pipeline of the blast furnace gas residual pressure power generation device (TRT), and is used for emergency shutdown; In case of crisis in the system, emergency shut-off should be implemented within 0.3-0.8 seconds to achieve reliable cut-off of pipelines, effectively preventing steam and condensate from backflowing or cutting off gas pipelines at the tail of the turbine, and protecting the safety of the turbine unit.