5.1 This test method is used to measure chemical permeation through specimens of protective clothing under the condition of intermittent contact of a test chemical with the specimen. In many applications, protective clothing is contacted intermittently to chemicals, not continuously as is tested by Test Method F739.

5.2 This test method is normally used to evaluate flat specimens and seams from finished items of protective clothing and of materials that are candidates for items of protective clothing.

5.2.1 Finished items of protective clothing include gloves, sleeves, aprons, suits, coveralls, hoods, boots, respirators, and the like.

5.2.2 The phrase "specimens from finished items" encompasses seams or other discontinuous regions as well as continuous regions of protective clothing items.

5.2.3 Selected seams for testing are representative of seams used in the principal construction of the protective clothing item and typically include seams of both the base material and where the base material is joined with other types of materials.

5.3 In some cases, it may be of interest to compare permeation behaviors that occur under conditions of intermittent contact with those that occur during continuous contact. Test Method F739 is recommended for measuring permeation under the conditions of continuous contact of the test chemical with the protective clothing specimen.

5.4 The breakthrough detection time, standardized breakthrough time, and the cumulative permeation are key measures of the effectiveness of a clothing material to be a barrier to the test chemical. Such information is used in the comparison of clothing materials during the process of selecting clothing for protection from hazardous chemicals. Long breakthrough detection times and standardized breakthrough times and low amounts of cumulative permeation are characteristics of more effective barrier materials than materials with higher permeation characteristics.

Note 1: At present, there is limited quantitative information about acceptable levels of dermal contact with most chemicals. Therefore, the data obtained using this test method cannot be used to infer safe exposure levels.

5.4.1 The reporting of a standardized breakthrough time greater than a specific time period does not mean that no chemical permeated through the protective clothing material since the standard breakthrough time is determined based on the permeation rate reaching a level of 0.1 μg/cm²/min. Some chemical had already permeated the specimen prior to the reported standardized breakthrough time.

5.4.2 The reporting of cumulative permeation over a specified test period is another means to report barrier performance of protective clothing for resistance to permeation. This measurement quantifies the total amount of chemical that passed through a known area of the material during the specified test period.

Note 2: It is possible to relate cumulative permeation test results to the total amount of chemical to which an individual wearer may be exposed by accounting for the exposed surface area and the underlying air layer. This information has potential value when there are known maximum permitted skin exposure doses for specific chemicals.

5.5 The sensitivity of the test method in detecting low permeation rates or amounts of the test chemical permeated is determined by the combination of: (1) the analytical technique and collection system selected, and (2) the ratio of material specimen area to collection medium volume or flow rate.

5.5.1 The analytical technique employed shall be capable of measuring the concentration of the test chemical in the collection medium at or below 0.05 μg/cm²/min.

5.5.2 Often, permeation tests will require measurement of the test chemical over several orders of magnitude in concentration, requiring adjustments in either the sample collection volume or concentration/dilution, or the analytical instrument settings over the course of the test.

5.5.3 Higher ratios of material specimen area to collection medium volume or flow rate permit earlier detection of permeation because higher concentrations of the test chemical in the collection medium will develop in a given time period, relative to those that would occur at lower ratios.

5.5.4 The sensitivity of an open-loop system is characterized by its minimum detectable permeation rate. A method for determining this value is presented in Appendix X1.

5.5.5 The sensitivity of a closed-loop system is characterized by its minimum detectable mass permeated.

5.6 Comparison of results of tests performed with different permeation test systems requires specific information on the test cell, procedures, contact and purge times, and analytical techniques. Results obtained from closed-loop and open-loop testing may not be directly comparable.

5.7 While this method specifies standardized breakthrough time as the time at which the permeation rate reaches 0.1 μg/cm²/min, it is acceptable to continue the testing and also report a normalized breakthrough time at a permeation rate of 1.0 µg/cm²/min.

5.7.1 It is permitted to terminate tests early if there is catastrophic permeation of the chemical through the protective clothing material and the rate of permeation could overwhelm the capability of the selected analytical technique.

5.8 A group of chemicals that is commonly used in permeation testing is given in Guide F1001.

5.9 Guide F1194 provides a recommended approach for reporting permeation test results.