ANNISTON ARMY DEPOT, Ala. -- With recent updates and changes to the last vat utilizing the chemical, the depot has eliminated Trichloroethylene, also known as TCE, from its cleaning processes.
The chemical compound trichloroethylene (C2HCl3) is a chlorinated hydrocarbon commonly used as an industrial solvent.
TCE has been a valuable tool for the depot because of its cleaning properties, low flammability and lack of a measurable flashpoint.
Bryan Hurst, an employee with the Directorate of Production's Cleaning, Finishing and Painting Division said the new solvent, DuPont's Vertrel SDG, is much better for his health and that of his coworkers.
With TCE, employees operating the chemical vats wore respirators to avoid breathing hazardous fumes. With Vertrel SDG, respirators are no longer necessary and the process takes about the same amount of time.
"The depot will have a reduction in air emissions," said Patty Dodson, an environmental engineer with the depot?'s Directorate of Engineering and Quality. "The new product is a volatile organic compound, but it is not a hazardous air pollutant."
According to the Code of Federal Regulations, a volatile organic compound, or VOC, is any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions, except those designated by EPA as having negligible photochemical reactivity.
Examples of VOCs include paints and lacquers, cleaning supplies, pesticides, building materials, craft materials such as glues and permanent markers.
Every vehicle or engine component slated for degreasing on the installation typically goes through a precleaning step - steaming or cleaning with water in the wash rack - before being dipped into the solvent vat, beginning a reaction which removes the oil. A vapor zone in the vat above the solvent dries the equipment, leaving a residue easily removed with blast media.
"The new chemical still works on the same principle as TCE - you heat the solvent at the bottom of the vat, creating a vapor zone and above that vapor zone is a refrigeration zone," said Dodson.
ANAD has been attentive to the latest technology in its goal to completely eliminate the installation's use of TCE.
In 2007, the depot reported to the Environmental Protection Agency that 118,903 pounds of TCE were either released as emissions to the atmosphere or disposed of as a hazardous waste.
The level fell to 12,070 pounds of TCE in 2012.
In the early 1990s, ANAD reduced the number of TCE degreasing vats from eleven to two by converting to alternate cleaning materials, such as alkaline cleaners in high pressure washers, petroleum solvent parts cleaning and improving efficiency at the steam cleaning wash racks.
"The primary reasons alternates were not successful substitutions for all vapor degreasing locations were deep holes in parts, such as gun barrels, and heavy grease in confined spaces, like roller bearings," said Steven Guthrie, an environmental engineer with the depot's Directorate of Risk Management. "Alternate cleaning methods were available to address these issues, but they typically required higher labor costs.
A few years ago, one of the two remaining vats was replaced with a smaller, more efficient unit.
The new vat covers a surface area of only 70 square feet, compared to the previous vat, which had a surface area of 125 square feet. It is this vat where testing on Vertrel SDG is being conducted.
The second vat was located in the depot's Small Arms Repair Facility, where mechanics disassemble used weapons to completely overhaul the parts, making like-new equipment for the troops. TCE was used to clean these weapons until the new Small Arms Repair Facility opened in 2011.
The new facility features an ultrasonic cleaning system, completely eradicating the need for TCE in the small arms repair and upgrade processes.
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