ALEXANDRIA, Va., Dec. 31 -- United States Patent no. 12,510,187, issued on Dec. 30, was assigned to Fisher Controls International LLC (Marshalltown, Iowa).
"Multi-stage shaft seal" was invented by Wade Helfer (Ames, Iowa).
According to the abstract* released by the U.S. Patent & Trademark Office: "A valve can include a valve body, a rotatable gate, a neck extending from the valve body, a shaft extending from the rotatable gate and through the neck, and a seal assembly configured to rotatably seal the shaft to the neck. The seal assembly can include a first stage seal having a first working temperature and coupled to the shaft at a first stage seal location, and a second stage seal having a second working temperature and coupled to the sha...