Pressure shaft seal and method

摘要: A shaft seal 10 and method, for use, example with a rotary drill bit in the oil patch industry, including an annular metal ring 12, elastomeric body 14 polytetrafluoroethylene liner 16. The has axially inwardly extending lubricant lip 18 outwardly mud 20. When pressure of exceeds particular value which is designed (for example, range 100-200 psi), causes to reverse direction allow be purged flow past both lips, until its reduced after returns (flips back) it original position. During purging, 20 acts as restricted opening controlling purging excluding drilling mud.