Abstract: Liquid chemical delivery systems are provided which include a liquid chemical storage canister, a pressurized gas source that feeds a pressurized gas into the storage canister, a vaporizer that may be used to vaporize the liquid chemical supplied from the storage canister, a delivery line that connects the storage canister to the vaporizer, a liquid mass flow controller that controls the flow rate of the liquid chemical through the delivery line, a reaction chamber that is connected to the vaporizer, and a liquid chemical recycling element that collects at least some of the chemical flowing through the system during periods when the liquid chemical delivery system is isolated from the reaction chamber.