System and method for monitoring mechanical seals

A method of monitoring a mechanical seal, which provides a seal between a rotating machine part and another machine part, to determine whether at least one seal face of said mechanical seal is worn, said method including the steps of:

• (a) providing at least one wear probe operably associated with at least one rotating component of said mechanical seal, said at least one wear probe being movable relative to said at least one rotating component, said at least one wear probe being configured to move relative to said at least one seal face independent of any wear of said at least one seal face, said at least one wear probe being configured to cause stress waves to be induced only when said at least one wear probe is in contact with said at least one rotating component;
• (b) providing at least one stress-wave sensor for measuring the intensity of stress waves induced by said at least one wear probe when it contacts said at least one rotating component;
• (c) providing means for gradually moving said at least one wear probe toward said at least one rotating component;
• (d) providing means for continuously measuring the distance that said at least one wear probe is moved;
• (e) gradually moving said at least one wear probe toward said at least one rotating component while evaluating the stress-wave signal measured by said at least one stress-wave sensor;
• (f) detecting the time when the intensity of stress-wave signal measured and evaluated in step (e) of this claim increases;
• (g) determining the distance that said wear probe moved at the time detected in step (f) of this claim;
• and,
• (h) evaluating the distance determined in step (g) of this claim to determine the wear level of said at least one seal face.

An apparatus for monitoring a mechanical seal, which provides a seal between a rotating machine part and another machine part, to determine whether at least one seal face of said mechanical seal is worn, said apparatus comprising:

• (a) at least one wear probe operably associated with at least one rotating component of said mechanical seal, said at least one wear probe being movable relative to said at least one rotating component, said at least one wear probe being configured to move relative to said at least one seal face independent of any wear of said at least one seal face, said at least one wear probe being configured to cause stress waves to be induced only when said at least one wear probe is in contact with said at least one rotating component;
• (b) at least one sensor for measuring the intensity of a first signal induced by said at least one wear probe when contacting said at least one rotating component;
• (c) an actuator for moving said at least one wear probe relative to said at least one rotating component so that said at least one wear probe and said at least one rotating component contact each other, said actuator and said wear probe being configured such that the force generated when said at least one wear probe contacts said at least one rotating component is substantially less than a force sufficient to damage said mechanical seal;
• and,
• (d) means for measuring and evaluating said first signal to determine if said mechanical seal is worn.