Perchlorate oxidizers have been used in propellants and pyrotechnics for many years due to their excellent performance and abundant availability. However, recent stringent regulations will limit the future use of this widely used oxidizer due to the ease of groundwater contamination which can result in serious environmental and health problems. These concerns have prompted the development of perchlorate-free pyrotechnics and propellants across the military. This project involved the reformulation of the pyrotechnic red flare compositions for the Navy Mk124 Marine Smoke and Illumination Signal (MSIS) and the Army M126A1 Ground Signal Illumination Red Star Parachute.
In order to achieve Navy and Army approval for use in in-service devices, the perchlorate-free compositions went through an extensive battery of tests including impact, friction, and electrostatic ignition sensitivity tests, cap sensitivity test, thermal stability test, vacuum thermal stability test, self-heating test (Differential Scanning Calorimetry, or DSC), aging characteristics, toxicity analysis (NASA-CEA modeling), small scale burning tests, the explosivity of dust test, and the Woods metal bath test. The formulation for the Mk124 passed all the required tests by the Naval Ordnance Safety and Security Activity (NOSSA) Office for Formulation Qualification and has been approved for use in Navy pyrotechnic items. Similarly, the formulation for the M126A1 passed the tests required by the Army’s Energetic Material Qualification (EMQ) in addition to the Navy’s NOSSA office for Formulation Qualification tests. Therefore, the perchlorate-free M126A1 red flare composition is jointly qualified for both Army and Navy use.
Since the new pyrotechnic formulations developed in this project contained no perchlorate ingredients, perchlorate contamination of the manufacturing facility and flare test ranges could not occur. This was verified by chemical equilibrium computer modeling of the new perchlorate-free compositions using NASA’s Computer Program for Calculation of Complex Chemical Equilibrium Compositions and Applications software (commonly referred to as NASA-CEA or NASA-Lewis modeling). These calculations did not predict any new environmentally objectionable combustion products relative to those produced by the in-service flare. The perchlorate-free Mk124 flares passed all the required flare performance specifications while also performing significantly better than the in-service composition. Specifically, the perchlorate-free compositions have higher luminous intensity or burn time in comparison to the in-service flare. This was a significant advantage for the principal users of this flare, namely downed aviators attempting to signal rescue aircraft.
The new perchlorate-free pyrotechnic flare compositions will eliminate the adverse impact to the environment of perchlorate contamination during manufacturing and testing operations. Elimination of the perchlorates from these compositions also will lead to a reduction in future cleanup costs of military facilities contaminated by perchlorate during the life cycle of the flares. Having environmentally acceptable colored signal flares available in the service inventories will avoid disruptions in training schedules as the U.S. Environmental Protection Agency and individual states continue to promulgate restrictive limits on perchlorate contamination in groundwater.