1. Scope

1.1 This practice covers the calculations of all the permeation parameters related to ASTM F 739, ISO 6529, and ASTM D 6978 standards by use of a computer program, referred to as Permeation Calculator (DHHS (NIOSH) Publication No. 2007-143c). The computer program is available either on the National Institute for Occupational Safety and Health website at http://www.cdc.gov/niosh/npptl/PermeationCalculator/permeationcalc.html or on CD by request. 1.2 This practice is applicable to both open and closed loop permeation tests. The closed loop test includes continuous sampling and discrete sampling. The discrete sampling includes tests when sample volume is replaced and also when sample volume is not replaced. For an open loop permeation test, the computer program also allows permeation data files with variable sampling flow rate. Refere to ASTM F 739 for more details about the different types of the permeation testing systems. 1.3 This practice is applicable to the most typical permeation behavior, that is, Type A, where the permeation rate stabilizes at a steady-state value. It shall not apply to the other types of permeation behaviors. Refer to ASTM F 739 for more details about the arious permeation behaviors. 1.4 This practice is not applicable to Test Method F 1383 because the permeation behavior is different under conditions of intermittent contact than under conditions of continuous contact. 1.5 This practice does not address the procedure of permeation testing. Refer to Test Method F 739, ISO 6529, or Practice D 6978 for the procedures in detail if needed.

Keywords

chemical protective clothing; permeation testing; permeation calculator; standardized breakthrough time; normalized breakthrough detection time; breakthrough detection time; minimum breakthrough detection time; steady-state permeation rate; cumulative permeation; computer program

Rationale

Permeation testing data analysis for chemical protective clothing has been performed in different manners. It is found that the differences in hand calculation values for the permeation parameters could be up to 30 % or more, resulting in incomparable results provided by different manufacturers or laboratories. Furthermore, the data analysis involves a number of equations and experimental factors. Although Test Method F 739, Practice D 6879, and ISO 6529 request calculating various breakthrough times, they provide no information on how to calculate. However, accurate calculation of the standardized breakthrough time for a closed loop test requires the use of polynomial curve fitting, polynomial derivatives, and quadratic equation solving, which are labor intensive and mathematically complex without a computer program. Calculation of the cumulative permeation at a given elapsed time requires integrating the area under the permeation curve with respect to any arbitrary time interval.

The title and scope are in draft form and are under development within this ASTM Committee.