Contaminant permeation testing of personal protective equipment

High throughput, low operating costs, and a reduction in variability have spurred adoption of this test at various DoD facilities

Medical & Biotechnology Military Technology

Schematic of the new contact test fixture

Permeation testing is a standard application for evaluating the diffusion of chemicals through a barrier. This is an important factor in choosing personal protective equipment (PPE) for laboratory personnel, industrial plant operators, farm workers, and emergency responders who interact with chemicals. However, standard permeation testing fails when faced with low volatility contaminants such as VX (nerve agent) as well as certain pesticides. Given the low volatility of select compounds, the standard vapor detection methods are insufficient without modification. Furthermore, VX has low water solubility, and organic solvents are not compatible with the test materials; thus, use of the ASTM method with a solvent collection is not appropriate.

Army scientists have filled the above gap in testing with the development of an improved device and method for measuring the permeation of low-volatility chemicals through PPE. The system (see figure) consists of a polycarbonate Petri dish, a polytetrafluoroethylene (PTFE) liner, a sorbent pad, a contaminated swatch, a smaller-diameter PTFE liner, and a stainless steel weight capable of delivering 1 psi to a 1 in. squared region. These components are contained within an inverted 8-ounce glass jar that allows for containment and safety in handling. With the exception of the stainless steel weight, the entire fixture was disposable, which reduces the potential for cross-contamination. Temperature control is achieved with an incubator modified with sliding shelves to facilitate access to individual jars.

The low-volatility agent permeation (LVAP) device is also appropriate for first responders; industrial and agricultural workers; and personnel working at the Environmental Protection Agency, National Institute for Occupational Safety and Health, or in law enforcement. The system is being used at several DoD-associated facilities.

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