Abstract
A pneumatically operated piston device has been developed which can be used to prepare gas mixtures in volumes up to 1 liter and dispense them at selected and controlled rates. It can be used to dispense liquids at constant rates from a glass or plastic syringe of any size. It is also useful for calibration of low-flow-rate rotameters. The device is built from commercially available metal cylinders and valves and is operated by compressed air or inert gases through a simple lever mechanism. A variable check valve controls the forward movement of the piston through a vernier which assures delivery of any flow rate. The unit operates in a horizontal plane, making it convenient for use from a bench top or mounted on a cart containing a small cylinder of nitrogen with a regulator.