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:
Jan. 14, 1997
Filed:
Mar. 02, 1994
Michel K Lovell, Marshalltown, IA (US);
Randall S Jackson, Marshalltown, IA (US);
Ronald R Brestel, Marshalltown, IA (US);
Fisher Controls International, Inc., Clayton, MO (US);
Abstract
A two-part, low friction, live loaded packing system for fire safety and low fugitive emission sealing (less than 500 ppm) of a valve stem at operating temperatures up to 450.degree. F. (232.degree. C.). One lower packing ring set around the valve stem has PTFE washers sandwiched between flexible graphite rings to provide fire safety and low friction. An upper packing ring set around the valve stem is closer to the loading source and has V-type PTFE rings to provide reliable low fugitive emission sealing and low friction. The live loading is optimized to maintain a seal at the upper packing set to less than 500 ppm leakage, minimize packing friction from both the upper and lower packing sets, and seal the lower packing set during fire safety tests.