Spring has arrived after a snowy cold wet winter for most of us in the USA. Brown trees, brown grass and gray skies are now changing to green buds, green grass and blue skies. Robins and yellow gold finches are showing up around our yard and feeder, heralding the beginning of a new season, spring. Our clocks have also been advanced an hour to allow for more day light time in the sun. As the season changes so does our selection of clothes and the need to continue to evaluate the performance of new protective clothing materials to new chemicals introduced into production in the workplace. Our protective clothing standard committees, ASTM F 23, AIHA PPE and international ISO are also planning their meetings for the year to adopt and review changes to improve test methods and/or develop new methods to meet performance standards. This past year, there seemed to be relatively little activity to report on protective standards development, however, I recently received a communication from a colleague in Sweden, Krister Forsberg, who is still active in international protective clothing standards development and publication of permeation data in the “Quick Selection Guide for Chemical Protective Clothing” soon to be released in its third reprint of the 5th Edition this year. He shared with me some documents that I would like to share with you in this column.
First, he provided a copy of a paper published in Science Direct, Polymer Testing 26 (2007) 1090-1099, Comparison of Permeation Resistance of Protective Gloves to Organic Solvents with ISO, ASTM and EN Standard Methods, Keh-Ping Choa, Jim-Shoung Lai, Hsueh-Chien Lin. In this study, the permeation resistance of nitrile and neoprene gloves to benzene and 1, 2 – dichloroethane were investigated using permeation cells according to the ISO 6529, ASTM F739, and EN374-3 standard test methods. All three methods used the same ASTM F 739 test cells. Conclusions from this study indicated that for either open loop gaseous or closed loop liquid medium the test cells showed no significant differences in breakthrough times as long as there was sufficient agitation in the collection chamber. Permeation rates were not comparable between the cells. This was thought to be due to the alternative configuration of the permeation cell used in the ISO 6529 method. The ASTM test cell is used with the test material in a vertical position, while the ISO alternative test cell is used with the test material in the horizontal position. It was also noted that increased flow rates of nitrogen in the open loop system increased permeability coefficients and eventually approached constant values, suggesting that the appropriate flow rate should be greater than 75 mL/min and 150 mL/min. for the ISO 6529 and ASTM F 739 cells, respectively. Overall, the methods showed comparable results for breakthrough time, which is usually considered the primary criteria for selection of glove materials.
Second he provided a revised version of the ISO 6529 test method and a proposed working group copy of an EN test method EN 374-4 for Protective Gloves Against Chemicals and Micro-Organisms –Part 4 Determination of Resistance to Degradation by Chemicals. Both of these methods are being considered for performance standards in the European community and are currently being reviewed..
Finally, a more recent development that has occurred with the ASTM F 739 test method is the need to select a new reference material for inter-laboratory testing. The standard 16 mil neoprene is still available on a limited basis through Pesce Lab Sales. Due to formulation differences in a new neoprene it will not be considered as a reliable reference material for future round robin tests. We are in contact with ASTM committee F23 and will be working with them as they select new reference materials, so that we can provide them to customers who would like to check their permeation test system. That is it for now, so enjoy spring and remember to contact Rich or me about any of your protective test method questions or test cells and systems.
Norm Henry