1. US4316460 - Gravitational flow system for the sequential administration of medical liquids

A gravitational flow system for the sequential administration of medical liquids to a patient comprises a primary container connected to a primary tube, a secondary container connected to a secondary tube, and a combined air barrier and liquid sequencing valve which connects them and is in fluid communication with a common tube extending to the patient. A primary flow control device is positioned in the primary flow path and a secondary flow control device is positioned in the secondary flow path. In operation the system dispenses primary liquid unless interrupted by a flow of secondary liquid. In that instance, primary liquid flow is cut off by an air capturing pocket. At the same time, a plurality of air barriers prevent infusion of air into the patient.