A novel system for safely transferring liquids from containers such as plastic jugs that are sealed by frangible seals, to conventional drums of the character having coupler-operated extractor valves. In one form of the invention, a standard coupler mechanism has been modified in a manner to provide means for rupturing the frangible seal of the sealed container without adversely affecting the manner in which the coupler is used to operate the extractor valve that is carried by the drum to which the liquid is to be transferred. Additionally, a novel adapter member has been provided for interconnecting the sealed container to the coupler mechanism.