| 摘要 |
PURPOSE:To prevent a flow passage from being closed by freezed moisture by making the surface of a part forming a throttle from a hydrophobic material. CONSTITUTION:Respective parts 3 and 4 of needle valve 1 and a valve seat 2 are subjected to hydrophobic surface treatment or lining. A suitable material for the purpose of the lining may be fluorine resin, polyacrylonitrile, copolymer of vinylidene chloride and acrylonitrile or the like. Because of the presence of the hydrophobic material, the freezing may mainly proceeds in the broader area of the flow passage behind the throttle, thereby preventing an expansion valve from being closed by freezed moisture, at the throttled part. |
