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 {HEAD ~ the lower packing set} during {TAIL ~ fire safety tests} 
during
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 { HEAD ~ the lower packing set } during { TAIL ~ fire safety tests }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL