A system can sequentially administer two fluids from a pair of containers (101, 102) to a patient. The system can have a delivery device (11) integrating two valve assemblies into a single device, and preferably each of the valve assemblies has two one-way valves and a pump communication port (124, 125). For example, the valve assemblies may share one or more walls and/or one or more chambers with each other. Preferably the only exits from the housing are attached to input tubing, output tubing, and connections to the pump. Preferably the system uses a single pump (12). By reversing the pumping direction of the pump, liquid may be sequentially drawn from one container or the other. The valve assemblies can use slit valves (13d) to prevent free-flow of the fluids.
