An apparatus for inoculating a sample to or withdrawing a sample from a vessel or conduit includes a body (3) with an internal collection chamber (24) formed therein. A valve operating rod (37) is movable to open and close an orifice (73) in the collection chamber (74). Furthermore, a drain passage (39) having an opening (73) in communication with the collection chamber (74) is located adjacent to or below the opening of the orifice (73). An inlet passage (25) having an opening in communication with the collection chamber (74) is located above the opening of the drain passage (39). A seal is formed between the movable valve operating rod (37) and the body (3), thereby separating and isolating certain mechanical parts of the valve from certain other process-contact parts of the valve. The seal is formed by one of seal glands, o-rings, flexible diaphragms or other device. Finally, a insulating jacket (33) is provided to insulate the inside chambers (23) of the valve from its surroundings.