Patent ID: 7472887

Claim:
A valve in a vacuum exhaustion system, the valve comprising: a first body having a valve seat formed on a bottom face of a valve chamber in communication with a fluid passage connected to a flow-in passage and a flow-out passage; a valve body permitted to rest on or move away from the valve seat, wherein the valve body is a metal diaphragm whose fluid-contacting parts are coated with fluorine-containing resin film; a driving means operating to allow the valve body to rest on or move away from the valve seat so the fluid passage is closed, or opened, for controlling fluid by allowing the valve body to rest on, or move away from, respectively, the valve seat; and an aluminum passivation applied at least on surfaces of the first body having contact with fluids and on an entire portion of the valve body that comes in contact with fluids, wherein the first body on which the aluminum passivation is applied comprises austenitic stainless steel containing 3-8 weight percent of aluminum, and wherein the aluminum passivation is applied on surfaces of the first body by heat treatment on the first body in order to prevent dissociation of fluid in a heated fluid passage of the valve and so that thickness of the aluminum passivation is not less than 20 nm, wherein the aluminum passivation is aluminum passivation containing Al 2 O 3 .