| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a back flow preventive device capable of being applied for various kinds of a special liquid by making the best use of a corrosion- resisting property of a valve casing coated with resin. SOLUTION: In this back flow preventive device, a valve chest 5 made by making a cylindrical dent from one side flange surface 3a is formed in a valve casing 1 subjected to resinous coating on the whole surface thereof. A valve element unit 10 is stored from the flange surface 3a. When a piping member 51 is flange-united to the flange surface 3a, the valve element unit 10 stored in the valve chest 5 is pressed by the piping member 51 and pressurized between an end surface of the valve chest 5 and the piping member 51, so that a valve component is assembled to the valve casing 1 without exposing material 7 from resinous coating 8.</p> |
