Suck back valve having diaphragm with thick walled section

摘要

A suck back valve comprises a valve body including a fluid passage having a first port formed at one end and a second port formed at the other end, and an air supply port for introducing a pressurized fluid; a displacement mechanism provided displaceably at the inside of the valve body, for making displacement in accordance with an action of the pressurized fluid introduced from the air port; a first diaphragm coupled to the displacement mechanism, for making displacement integrally with the displacement mechanism; and a seat section provided to face to the fluid passage, for seating the first diaphragm or making separation from the first diaphragm.