When choosing chemical protective apparel, it is recommended that both Penetration and Permeation testing be considered.

PENETRATION
Penetration is the flow of bulk liquid through a material, or through seams or closures. Penetration resistance of protective clothing materials is measured using ASTM F903, a standard test method that visually determines material barrier performance against liquid chemicals under conditions of continuous contact. This test is specified for protective clothing materials in both NFPA 1992: “Standard on Liquid Splash Protective Suits for Hazardous Chemical Emergencies” and NFPA 1993: “Standard on Support Function Protective Clothing for Hazardous Chemical Operations.”

Description of Test - ASTM F903-95 Exposure Protocol C: “Standard Test Method for Resistance of Protective Clothing Materials to Penetration by Liquids.” A protective fabric swatch is placed into a test cell. The chemical barrier side of the fabric is placed in contact with a test chemical for one (1) hour with part of the contact period performed under pressure. The condition of the fabric on the other (interior) side is periodically monitored to determine if the test chemical is seen penetrating the fabric.

Results - Expressed as PASS or FAIL. A material passes the test when there is no visual evidence of liquid penetration after the one hour test period. Any visual detection of penetrating liquid during the test period constitutes a failing performance.

PERMEATION
Permeation is the process by which a chemical moves through protective clothing material on a molecular level. ASTM F739 provides a standard test method designed to measure the resistance of protective clothing materials to permeation by chemical liquids and gaseous chemicals under condition of continuous contact.

Description of Test - ASTM F739-96: “Standard Test Method for Resistance of Protective Clothing Materials to Permeation by Liquids or Gases Under Conditions of Continuous Contact.” A protective clothing fabric swatch divides a test cell into two different chambers. Chamber A is filled with the chemical being tested. A collection gas or liquid is used in Chamber B in combination with an analytical instrument (analyzer) to detect chemical molecules permeating into Chamber B through the fabric.

Result: Permeation Rate - The maximum rate at which a permeating chemical passes through the fabric as measured by the analyzer. It is reported as micrograms per square centimeter of fabric per minute. In come cases the permeation rate is so high that the analyzer becomes saturated; in these cases, Kimberly-Clark reports a result of “High.”

Result: Normalized Breakthrough - The elapsed time (reported in minutes) measured from the start of the test to the time the permeating chemical reaches a permeation rate of 0.1 µg/sq cm min. Normalized Breakthrough Time is reported in order to allow the user to compare test results from various labs, test equipment, and manufacturers.

If the chemical demonstrates permeation at the first time of measurement, Kimberly-Clark reports the result as “Immediate.” In some cases, there is no permeation above a rate of 0.1 µg/sq cm min detected prior to the 480 minute length of the test; in these cases, Kimberly-Clark reports the result as “> 480.”