Researchers test barrier coatings to protect DOD facilities

  • Published
  • By Mindy Cooper
  • AFRL Materials and Manufacturing Directorate
TYNDALL AIR FORCE BASE, Fla. --  Air Force Research Laboratory researchers, in conjunction with the Defense Threat Reduction Agency and Joint Science and Technology Office, have conducted extended research on protection technology for structures against chemical warfare agents. 

The research, overseen by AFRL's Materials and Manufacturing Directorate , helped define the parameters for DTRA to protect structures like tents and buildings from  chemical agents, and has resulted in transition of the technology to the Joint Expeditionary Collective Protective program.

"The facilities where military personnel perform their duties need to be protected from chemical warfare agent attacks. In the event of an attack occurring outside of a work facility, there needs to be a method of protecting the structures from being permeated by the threat," said Mr. Mike Henley, the Barrier Coating Program Manager, "DTRA and JSTO initiated a research program with the [Materials and Manufacturing Directorate] Airbase Technologies Division at Tyndall Air Force Base, Fla., and in-house contractors, Applied Research Associates, Inc. to begin identifying and testing commercial off the shelf products that may meet their needs."

"Researchers sought products personnel in the field could apply quickly and easily to the inside of a structure," Henley said, "They wanted a product that could stop the air that is already inside the structure from leaking out, as well as protect the structure from a chemical that is released outside which may penetrate vulnerable leakage areas. It was essential that the product be able to be applied using simple tools like paint sprayers."

Six commercial products were selected for in-lab and large scale tests: ALARA 1146, Tubcoat 4410, Stripcoat TLC Free, LINE-X, Olympic latex paint and sandable polyurethane foam.

According to Henley, the researchers prepared small samples of each product for in-lab testing to determine how long each material could last before being permeated by a chemical threat. The samples were applied to a substrate material, allowed to dry, and then punched into small circular coupons for permeation testing. The coupons were placed inside a permeation cell and locked. A chemical warfare simulated agent was then released into the cell. Researchers measured how long it took for chemical vapor to permeate each coating. ALARA and Tubcoat provided excellent barrier protection with permeation times equal to and longer than the M28 chem-bio protective material that is currently used in the field.

Large scale tests were also performed on each product, Henley said. A 8-foot-tall by 8-foot-square portable shed testing facility was outfitted with wood paneling, ceiling tiles, an electrical outlet, insulation and a window. Before any coatings were applied, the facility was tested for the base level of air leakage using a Minneapolis blower door. A blower door consists of a calibrated fan for measuring an air flow rate and a pressure sensing device to measure the pressure created by the fan flow. The combination of pressure and flow can be used to determine how airtight the facility is. Leakage of the outfitted test facility was approximately 700 standard cubic feet per minute at 1/2 inch of water gauge pressure.

"Each product was applied to the entire inside of the facility, ceiling to floor, and allowed to dry for 24 hours. After the coating was dry, researchers performed the Minneapolis blower door test a second time," Henley said. "All of the coatings tested resulted in a 70-90 percent leakage reduction. A reduction like this will not only protect personnel from chemical threats but will reduce the amount of energy needed to ventilate certain facilities."

While research is ongoing, researchers have identified select non-toxic, water-based coatings that can be applied to the interior of the facilities, dried and then peeled off as a practical protective solution in the event of a chemical threat. Two products they identified as successful were ALARA and Tubcoat. The JSTO was so pleased with the research program that they plan to transition the technology to the Joint Expeditionary Collective Protective this year.