Significance and Use
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 from finished items of protective clothing and of materials that are candidates for items of protective clothing.
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 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 as 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 cumulative permeation are characteristics of better barriers.
5.4.1 The reporting of a standardized breakthrough time greater than a specific time period does not mean that no chemical has permeated through the protective clothing material as the standard breakthrough time is determined based on the permeation rate reaching a level of 0.1 μg/cm2 min, indicating that some chemical has already permeated the specimen prior to the reported standardized breakthrough time.
5.4.2 Cumulative permeation represents the mass that permeates through a protective clothing material over a specific period of time for a specific surface area of material. It is possible to use this information to model how much chemical can enter an item of protective clothing for a particular exposure based on a knowledge of the exposed surface area, the free volume inside the protective clothing item, and amount of air mixing or air exchange for the protective clothing item.
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 should be capable of measuring the concentration of the test chemical in the collection medium at, or below, levels consistent with standardized breakthrough time value specified in 3.1.15.
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.
5.6 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 A group of chemicals that is recommended for use in permeation testing is given in Guide F1001.
Scope
1.1 This test method measures the permeation of liquids and gases through protective clothing materials under the condition of intermittent contact.
1.2 This test method is designed for use when the test chemical is a gas or a liquid; where the liquid is either volatile (that is, having a vapor pressure greater than 1 mm Hg at 25°C) or soluble in water or another liquid that does not interact with the clothing material.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 7.
