The Gas Permeameter is designed to measure the permeability of core specimens one inch in diameter and one inch in length. A core specimen is placed into a core sleeve, which is then inserted into the “Modified Hassler” style test cell. Nitrogen at a constant flow rate is forced through the core and the differential pressure across the core is measured. The flowrate is measured with calibrated flowmeters. Viscosity is easily determined by the use of nitrogen property tables. These variables are incorporated into Darcy’s law to calculate sample permeability.