Shut off valve for medical suction apparatus

A medical suction apparatus for receiving and containing fluid from a patient during a medical procedure, comprising:

• a canister for receiving and containing the fluid from the patient;
• a lid for sealably covering said canister;
• at least one suction port formed on said lid and communicating between the interior and exterior of said canister covered by said lid;
• a plunger guide mounted within said canister covered by said lid and including a plurality of fingers depending downwardly from said lid adjacent said suction port and a generally vertical tubular means depending from said fingers disposed directly below said suction port;
• a plunger formed from a flexible material and including an upwardly facing concave surface integrally formed on the top of said plunger, said concave surface including an upwardly facing concave disc attached to said plunger at the center of said disc and having a diameter greater than the diameter of said plunger, so that the disc engages the top of the tubular means to limit the downward sliding motion of said plunger, said plunger and said tubular means being cylindrical with the lower end of said tubular means including an aperture for allowing fluid to enter said tubular means to float said plunger;
• and
• said plunger being supported within said tubular means for sliding motion, so that when the fluid within the canister is below a predetermined level, air may pass from within said canister between said fingers and into said suction port, and when the fluid within the canister rises to the predetermined level, the plunger floats and slides upwardly in said tubular means forcing said concave surface into a sealed relationship covering and blocking said suction port.