The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 03, 1998
Filed:
Sep. 29, 1994
James R Wasser, Des Plaines, IL (US);
Douglas J Volden, Park Ridge, IL (US);
James P Netzel, Skokie, IL (US);
John Crane Inc., Morton Grove, IL (US);
Abstract
A double, back to back oriented mechanical end face seal arrangement for use in sealing pumps or other devices used in fluid transfer of toxic or corrosive fluid has an intermediate buffer fluid chamber into which a relatively inert gas, such as nitrogen, is provided for use as a buffer fluid, and is maintained at a pressure which exceeds the process fluid pressure by at least 10 p.s.i. Each seal has a primary ring and a mating ring with gap maintaining means, such as spiral pumping grooves, formed in one of the rings which are shaped and dimensioned to pump the buffer gas through the first seal from the intermediate chamber into the process fluid chamber against the process fluid pressure and through the second seal from the intermediate chamber into the environment external to the housing and sealing area, thus avoiding the escape of the process fluid into the intermediate buffer chamber and thereby to the atmosphere. The inboard seal includes a first secondary sealing means disposed between one seal ring and the housing for sealing therebetween and a second secondary sealing means, disposed between the other seal ring and the shaft for sealing therebetween, the first and second secondary sealing means, which may comprise O-rings, each defining the boundary between the intermediate chamber and the process fluid chamber. The first and second secondary sealing means of the first rotary mechanical end face seal are sized and disposed to define radial walls in the back radial surfaces of each seal ring to thereby present essentially an equal area at an approximately identical radius, such that essentially the same mount of buffer fluid pressure acts on the back radial surfaces of each ring of the first rotary mechanical and face seal but in opposite directions and, on the process fluid side, the identical process fluid pressure acts on opposite sides of a portion of the respective rings of the first rotary mechanical end face seal essentially eliminating thrust forces acting on the first rotary mechanical end face seal.