Microwave heating digestion vessel

A moveable heating digestion vessel for use in a microwave oven during microwave heating digestion of a material, comprising:

• a. a molded threaded fluorocarbon vessel and mating molded threaded fluorocarbon large cap for covering said vessel, said vessel and said large cap being transparent to microwave energy;
• b. a valve body assembly portion of said large cap positioned on the top of said large cap and extending outwardly therefrom, said valve body assembly including a ball seat, a valve port extending from said ball seat inwardly through said large cap, a vent port opening extending from said ball seat outwardly through said large cap to the atmosphere, and an externally threaded hollow cylindrical neck coaxially aligned with said ball seat and extending outwardly from said large cap;
• c. a valve ball member of fluorocarbon material, having a spherical end portion for mating with said ball seat and a hollow cylindrical portion for retention of spring assembly and limiting the range of travel of said ball member;
• d. a threaded valve cap of fluorocarbon material for engaging on said threaded neck and having an interior stop for engagement with said cylindrical portion of said ball member to limit travel of said ball member;
• e. indicia on said large cap and said threaded valve cap indicating the relative position;
• and,
• f. a non-metallic spring assembly positioned coaxially within said hollow cylindrical portion of said valve ball member and bearing against said threaded valve cap and said ball member to bias said ball member against said ball seat with a predetermined force, whereby said bias force and therefore also the internal pressure within said vessel required to open said valve ball member from said ball seat is adjustable by rotating said threaded valve cap on said valve body assembly and indicated by said indicia, and pressure is thereby relieved through said vent port opening.