A system for building a gas processing apparatus includes a compressed gas source, a pressure modulator in communication with the gas source, and a chamber configured to receive a gas permeable material. The chamber is further configured with a first chamber area on one side of the material and with a second chamber area on a second side of the material. A sensor is configured to measure over time a pressure differential between the first and second chamber areas. A memory stores performance characteristic data for a plurality of gas processing apparatus. A processor converts the pressure differential to a material characteristic of the gas permeable material, and compares the material characteristic to at least one selected performance characteristic of the gas processing apparatus.