LOW FRICTION PACKING

摘要

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 DEG F. (232 DEG 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.