A system and method are provided for selectively containing and dispensing a predetermined liquid material in and from a source container in failsafe manner, wherein a housing is disposed to receive a pressurized fluid stream, and a selectively operable valve assembly is disposed in a flow path defined in the housing. The housing includes an inlet, an outlet, and an intermediate portion extending therebetween, which is formed with an admission port for admitting the predetermined liquid material. The valve assembly is disposed between the housing's inlet and outlet, and may be selectively operated to alternatively open and close access of the predetermined liquid material into the housing. The valve assembly is operably actuated responsive at least in part to the pressurized fluid stream in the flow path, whereby admission of the predetermined liquid material into said housing is keyed by introduction of the pressurized fluid stream into the flow path.