Mechanical face seal for sealing slurry liquid

摘要

A mechanical seal for sealing a slurry liquid between a casing and a rotary shaft comprises a fixed seat ring; a rotatable slide ring in the casing and abutting against the seat ring to form a sealing face therebetween; a helical spring in the casing and surrounding the rotary shaft, and biassing the rotatable slide ring toward the seat ring; and a rotatable ring on the rotary shaft and rotatable with the rotary shaft and holding the spring at a predetermined position relative to the rotary shaft, the spring being interposed between the rotatable slide ring and the rotatable ring. A small space is provided between the casing and the rotatable ring and the rotatable ring has a helical projection on the outer surface thereof. The helical projection of the rotatable ring and the helical spring are directed such that upon rotation thereof a force is produced in a direction away from the sealing face and toward the interior of the casing. The spring is preferably a helical screw-thread-like member of rectangular cross-section.