Removal of Perchlorate Oxidizers from Pyrotechnic Flares
Chemical oxidizers containing perchlorate ions have been widely used in the U.S. Department of Defense (DoD) pyrotechnic applications since they are highly reactive, inexpensive, and have a long shelf-life. Unfortunately, perchlorates are highly water soluble and can inhibit proper thyroid function when ingested. This problematic combination of characteristics has led to increased scrutiny of perchlorates by the Environmental Protection Agency (EPA). An EPA Interim Health Advisory level of 15 ppb has been set for perchlorate ion levels in drinking water supplies, and more stringent regulations are expected. Furthermore, perchlorate regulations have directly impacted various DoD operations including suspension of training with the M116 flash bang simulator in 1997, closure of the Camp Edwards ordnance testing site in 2000, and costly remediation of many perchlorate-contaminated DoD sites.
To help the DoD stay in front of future regulations, the Crane, Indiana division of the Naval Surface Warfare Centers (NSWC Crane) and the Army Research and Development Engineering Center at Picatinny, New Jersey (ARDEC) have developed an array of perchlorate-free pyrotechnic signal flare compositions through SERDP- and ESTCP-funded efforts. Development of these compositions started with small, laboratory-scale proof-of-concept experiments to show that they could produce the proper color of light with enough intensity to replace existing, perchlorate-containing compositions. So far, red, green, yellow, and white signal flare compositions have all been developed. Once a potential composition was identified, the ability of the composition to be accidentally ignited by impact, friction, and static electricity was measured to make sure that it would be safe to manufacture and use. After this safety check, larger batches were mixed to test whether they could reliably be made with existing manufacturing equipment. Finally, full-up colored flare signals using the perchlorate-free compositions were made and tested to compare their performance to the currently used, perchlorate-containing signal flares. After these compositions have been shown to meet or exceed the items’ performance requirements, the flare compositions are subjected to a stringent qualification process to show that they are safe for use in Army and/or Navy applications.
To date, the joint NSWC Crane and ARDEC efforts have successfully demonstrated perchlorate-free flare compositions in the Mk124 Marine Smoke and Illumination Signal (red), Mk141 Submarine Smoke and Illumination Signal (green), M126A1 Signal Illuminant Red Star Parachute (red), M195 Signal Illuminant Green Star Parachute (green), and M158 Signal Illuminant Ground Red Star Cluster (red). As a result of these demonstrations, the in-service M126A1 and M195 signals now utilize perchlorate-free compositions, and plans are underway to transition the other signals to perchlorate-free compositions. Reformulation efforts for the Mk80 Signal Pen Flare (red), Mk134 Signal Pen Flare (white), A/P25 Signal Pen Flare (red), and Mk140 Submarine Smoke and Illumination Signal (red) are also currently underway.