Fall will officially arrive later this week. Baseball playoffs will start soon, football season has begun, and there are fewer hummingbirds in my garden. Also, the leaves on the trees are turning color and soon will falling to the ground. All this is to remind me it’s time for my fourth quarter column. A lot has happened since my last column was written,particularly the devastation caused by hurricane Katrina and the aftermath that followed with displaced families, destroyed homes and lives. Nature can be cruel, so we must be prepared for the worst. Fortunately, we were spared the winds and rain, but Katrina did cause scheduling changes for our ASTM F23 Committee meeting originally set for New Orleans in January. It will now be in Phoenix, Arizona instead.
I thought I would focus this column on lab set ups for doing permeation studies, since during the year I get questions on facilities and equipment for doing permeation studies.Once you have the test cells you definitely need a bench top and ventilated enclosure to do testing on your own. The ventilated enclosure is only necessary if you are working with hazardous chemical vapors. The bench top should be solid and have some type of containment tray for liquid spills. Storage of the chemicals should also be considered, particularly for flammable solvents. A source of electrical power is needed for analytical equipment, stirring motors and light. As for analytical equipment, there are a number of different types of sampling devices and detectors. The choice of these is dependent on the chemical being tested (liquid, gas or vapor) detection limits and whether you are using open or closed loop configurations. The cells can be connected to a sampling manifold to automatically switch to three cells at different time intervals to do triplicate testing. My recommendation is to use common wet chemical analytical methods, gas or liquid chromatography, ionization detectors or infra-red analyzers. Most of these methods can be found published in the NIOSH Manual of Analytical Methods and are commonly used by industrial hygienists for air analyses. These methods are also validated by NIOSH for reproducibility and performance. On occasion, I also have used color indicator tubes and pH paper to screen potential clothing materials to see if breakthrough occurs. As for safety considerations please remember to read the information on the Material Data Safety Sheet (MSDS). Even though you are working with small volumes of chemicals you should be familiar with their physical and chemical properties, particularly for waste disposal. This is only a brief attempt to provide basic start up lab set ups, so perhaps next year I will focus on more specific types of permeation set ups in my quarterly column. For now, I wish you a safe and happy fall as the holiday season approaches and the year 2005 winds down.