Abstract: In a first aspect, a liquid delivery system is provided that includes a first liquid delivery module adapted to store and dispense a first chemical and a second liquid delivery module adapted to store and dispense a second chemical. The liquid delivery system further includes at least one connecting mechanism coupled to the first and second delivery modules and adapted to couple the first and second delivery modules to a substrate processing device. Each delivery module includes a vessel including a first chamber and a second chamber. The vessel is configured to receive a liquid from a bulk supply and to receive a pressurized flow of gas from a gas source. Each liquid delivery module also includes a valve assembly operable to selectively permit fluid communication between the first chamber and the second chamber during a non-refill state and to prevent fluid communication between the first chamber and the second chamber during a refill state.