Pump safety device

A pump having a casing, a pump shaft rotatably mounted within said casing, a high pressure fluid chamber, a low pressure fluid chamber, and a dynamic gasket mounted in said casing and contacting said shaft for separating said high pressure chamber from said low pressure chamber and a safety device, comprising:

• a compressible safety gasket;
• a cylindrical piston coaxially surrounding said shaft and having a first sealing surface facing a second sealing surface on said shaft with said safety gasket received therebetween, said first sealing surface being spaced from said second sealing surface by an amount such that said safety gasket is in an uncompressed state, said cylindrical piston being mounted in a chamber formed in said casing for movement axially of said shaft;
• and
• means for moving said cylindrical piston axially of said shaft to compress said safety gasket between said first and second sealing surfaces in the event of a rupture of said dynamic gasket, whereby, while said dynamic gasket is operative, said safety gasket is not used, but when said dynamic gasket ruptures and high pressure fluid enters said low pressure chamber, said safety gasket is compressed to prevent leakage of fluid from said low pressure chamber.