H42W/H/Y vertical check valve API6D, in strict accordance with GB/T12235 standard design and manufacture, this series valve is normally closed, due to the pressure of the inlet medium in the pipeline, and to overcome the spring resistance makes the valve opens. When the inlet pressure of medium below the outlet, the spring into the valve core seat and make the valve closed, stop medium counter-current, start-stop function back. This valve with spring support valve core, the vertical?or?horizontal installation is adopted. This product is widely used in petroleum, chemical, pharmaceutical, electric power industry and other various working condition of the pipeline.