Volume 2, Issue 6 (November 1974)
The Calculation of Gas Transmission Rates Measured by Manometric Methods
It is shown that an error in the calculated gas transmission rate of greater than 20 percent can result when using the standard equation presented in Method M of the American Society for Testing and Materials Test for Gas Transmission Rate of Plastic Film and Sheeting [D 1434–66 (1972)]. The magnitude of this error is shown to be a function of both cell void volume and pressure. Therefore, disagreements in results calculated using different cells and operating conditions can be explained. The exact solution of the equation is presented together with an approximation; the latter facilitates calculations and results in an error of less than one percent.