Gas-handling systems, subassemblies, and components constructed from metals and plastics alike need to be tested for pressure loss and leakage. In this study, the concept of conductance or characteristic leak rate has been further developed for pressurized scenarios and applied to a model system. Conductance was measured from both pressure-decay experiments and from constant pressure-flow experiments using three different,gases at three different temperatures. Results from the two types of tests were compared using an analysis developed as part of this study. Conductance values from decay and steady-state measurements were in general agreement. Thus, in the evaluation of real components, subassemblies, or systems, conductance can be estimated from a simple pressure-decay measurement and then used to estimate steady-state performance.