Disposable interconnected pump cassettes having first and second pump chambers with valved inlet and outlet connections

A disposable set of n interconnected pump cassettes comprising:

• a first infusion line to the set connected to a distribution line of the set that has n branches, each branch connected to a respective first inlet of each of the n pump cassettes;
• n second infusion lines to the set, each one of the n second infusion lines configured to connect one of n separate solution sources to a respective one of n second inlets of the n pump cassettes;
• each one of the n pump cassettes comprising a first and a second pumping chamber, wherein for each pump cassette of the n pump cassettes:
• wherein the first inlet of each cassette connects via a single valve only to the first pumping chamber, and the second pumping chamber has a valved connection to the second inlet of each of the n pump cassettes, an outlet of the first pumping chamber has a valved connection to the second pumping chamber, and an outlet of the second pumping chamber has a valved connection to an outlet of each of the n pump cassettes;
• each one of the outlets of the n pump cassettes is connected to a respective one of n containers via a flexible line, each container configured to receive a mixture of fluid from the first inlet and the second inlet of a pump cassette to which said container is connected;
• and
• wherein each said pumping chamber comprises a flexible membrane configured to pump fluid in and out of the pumping chamber, and configured to mate with a base unit that provides positive or negative pneumatic actuation pressure to the flexible membrane.