Air seal for pump with vertical shaft

A sealing apparatus for a vertical centrifugal pump having a rotary shaft with a lower end operably connected to an impeller, said impeller rotating within a cavity in the pump to pressurize fluid entering the cavity, said sealing apparatus comprising:

• a chamber containing gas circumferentially disposed about the shaft, said chamber in fluid communication with the cavity;
• a stationary assembly disposed about the shaft and forming a second chamber for containing liquid;
• a rotary assembly disposed about and connected to the shaft, a portion of said rotary assembly extending over a portion of said stationary assembly;
• said rotary assembly and said stationary assembly forming sealing means to prevent the escape of gas from the chamber when the fluid enters said chamber from said cavity, said portion of said rotary assembly extending into the second chamber such that said extending portion of said rotary assembly is submerged in the liquid to constitute part of said sealing means, and stationary assembly including a rotary sealing means circumscribing and contacting a face of said rotary assembly for sealing between said face and said stationary assembly, the flow of fluid into said gas filled chamber compressing the gas within said chamber to form a buffer to prevent contact between the fluid and the rotary sealing means, said sealing means inhibiting the flow of liquid from said second chamber due to the compression of gas in said gas chamber.

A sealing assembly to seal about a rotary shaft of a vertical pump assembly, the pump assembly including an impeller rotating within a cavity to pressurize a fluid entering the cavity, the sealing assembly comprising:

• a pump housing;
• a gas filled enclosed chamber formed within said housing and in communication with the cavity;
• a liquid filled chamber in communication with said gas filled chamber for preventing the escape of gas from said gas filled chamber when the fluid enters said gas filled chamber;
• and
• rotary sealing means for inhibiting the flow of liquid from said liquid filled chamber into the environment surrounding said housing, the flow of the fluid into said gas filled chamber compressing the gas within said chamber to form a buffer to prevent contact between the fluid and the rotary sealing means.