The present invention can provide a system and method for D LCO quality control testing and can include an apparatus for testing a pulmonary diagnostic device capable of performing single breath carbon monoxide uptake measurement, comprising: a single gas-tight chamber, with a gas port configured to receive gas from or to expel gas to the exterior of the chamber and a partition configured to change the volume of the single gas-tight chamber; the single gas-tight chamber capable of expanding and contracting; a member disposed within the single gas-tight chamber and configured to limit the movement of the partition, the member being adjustable to set a predetermined maximum volume of the single gas-tight chamber and a predetermined volume of D LCO test gas that the single gas-tight chamber can receive; and an interface configured for the transfer of gas between the pulmonary diagnostic device and the simulation device via the gas port.