A mechanical seal configured for sealing a pressurized, compressible fluid within a sealed volume , the seal comprising: a rotating sealing ring surrounding a rotating shaft , the rotating sealing ring being rotationally cooperative with and sealed to the rotating shaft ; a stationary sealing ring cooperative with and sealed to a housing that is penetrated by the rotating shaft , a stationary seal face of the stationary sealing ring being substantially parallel to a rotating seal face of the rotating sealing ring , the rotating and stationary seal faces being separated by a seal gap such that the compressible fluid can only escape from the sealed volume by passing through the seal gap ; characterized in that said seal further comprises: at least one shock inducing section included in the seal gap , the shock-inducing section including a converging segment within which a cross section of the seal gap narrows followed by a diverging segment within which the seal gap widens, so that a local minimum in seal gap width, referred to herein as a "choke point," is formed between the converging segment and the diverging segment ; the converging and diverging segments being configured to cause the compressible fluid when flowing radially or axially outward through the seal gap to be accelerated within the shock-inducing section into a supersonic state, so that a shockwave is formed by the fluid within the diverging segment , thereby reducing a stagnation pressure of the fluid. a rotating sealing ring surrounding a rotating shaft , the rotating sealing ring being rotationally cooperative with and sealed to the rotating shaft ; a stationary sealing ring cooperative with and sealed to a housing that is penetrated by the rotating shaft , a stationary seal face of the stationary sealing ring being substantially parallel to a rotating seal face of the rotating sealing ring , the rotating and stationary seal faces being separated by a seal gap such that the compressible fluid can only escape from the sealed volume by passing through the seal gap ; characterized in that said seal further comprises: at least one shock inducing section included in the seal gap , the shock-inducing section including a converging segment within which a cross section of the seal gap narrows followed by a diverging segment within which the seal gap widens, so that a local minimum in seal gap width, referred to herein as a "choke point," is formed between the converging segment and the diverging segment ; the converging and diverging segments being configured to cause the compressible fluid when flowing radially or axially outward through the seal gap to be accelerated within the shock-inducing section into a supersonic state, so that a shockwave is formed by the fluid within the diverging segment , thereby reducing a stagnation pressure of the fluid. at least one shock inducing section included in the seal gap , the shock-inducing section including a converging segment within which a cross section of the seal gap narrows followed by a diverging segment within which the seal gap widens, so that a local minimum in seal gap width, referred to herein as a "choke point," is formed between the converging segment and the diverging segment ; the converging and diverging segments being configured to cause the compressible fluid when flowing radially or axially outward through the seal gap to be accelerated within the shock-inducing section into a supersonic state, so that a shockwave is formed by the fluid within the diverging segment , thereby reducing a stagnation pressure of the fluid. <EOS>