(Released 17 June 2015) The Defense Threat Reduction Agency is leading an effort to design a new Warfighter uniform―with added protection against chemical warfare agents encountered in the field―and ECBC scientists are using both standard and new methods to test fabrics that will be used in the new suit.
The new uniform is designed to decrease thermal burden to the Warfighter, while maintaining the same or better protection against chemical agents. Different fabrics may be used in the uniform based on where heat is more common, like the chest and groin area; but a greater protection factor is needed for places where the Warfighter is likely to come in contact with agent, such as on the shoulders, elbows or knees.
The effort is part of a joint U.S. Army and Air Force program called the Integrated Protective Fabric System (IPFS) program. It is led by the U.S. Army Natick Soldier Research Development and Engineering Center (NSRDEC) and the U.S. Air Force Civil Engineering Center, and supported by ECBC. Other organizations involved in the program include Calgon/Chemviron, Emory University, Enropics and Phasex.
In collaboration with NSRDEC, the ECBC Permeation and Analytical Solutions Branch (PASB) was recently involved in testing agent absorption on different fabrics that could be used in the IPFS, now in the Milestone B phase of development. All testing needed to meet the chemical and biological defense program test and evaluation standards, as well as the requirements of the IPFS program.
“Natick brought us on board based on our previous work with them, as well as our unique ability to test using live agents and our understanding of transport phenomenon,” said Brian MacIver, PASB chief. “The quality of our labs and test methods, and our reach-back support from subject-matter experts in toxicology and decontamination from across the Center make us aneal partner for this type of program.”
To test the fabrics, branch scientists used innovative and effective test methods toentify reactions between CWAs and the material. Three test methods were used―low-volatility agent permeation (LVAP), air liquid vapor aerosol group (AVLAG) and advanced super-shedding efficacy test (ASSET)―the latter being a brand-new capability developed specifically for this program.
The LVAP method was recently developed by ECBC researchers and and will soon become an official test and evaluation method with the U.S. Department of Defense for VX permeation through protective equipment. The method has been validated through the Deputy Under Secretary of the Army-Test and Evaluation, and permits the experimental evaluation of protective materials against contaminants that were traditionally difficult to analyze.
Following standard test operations procedures, scientists used the AVLAG test cell to evaluate multiple layers of experimental carbon and shell fabrics to measure quantitative permeation of specific agents through the material. From past development efforts, the PASB has been able to well-characterize the AVLAG system, reducing variability in the data through more accurate control over testing variables that are inherent to AVLAG or any other test cell or device.
The branch supported the development of “super-shedding” coating capability specifically for this program. A modification of the AVLAG method, the ASSET method uses a different application of agent to the material. “With this method, we aided NSRDEC in their development of fabric that sheds (repels) liquid contamination,” explained Christopher Steinbach, a chemist supporting the PASB. “The coating reduces agent permeation by allowing agent to run off the fabric.”
To perform the ASSET tests, scientists used the same AVLAG cells, but placed on a tilt table custom built by the ECBC Advanced Design and Manufacturing Division. The table was tilted at a range of 45 to 75 degrees so the agent could run off the fabric swatches. “The tilting represents a Warfighter’s movements, as well as the how the uniform will naturally conform to their body,” said Steinbach.
Then samples of air were pulled from the cells every few minutes to develop a curve for the growth of the concentration of agent on the fabric. The cells were monitored in real time for 24 hours, with 13 to 26 cells being used at a time. “The higher throughput allows for better statistics for evaluation,” said Steinbach.
ASSET testing will continue through FY15. Any necessary follow-on testing will be conducted at the request of NSRDEC.