After two successful Strategic Environmental Research and Development Program (SERDP) projects (WP-2148 Development of Low-Toxicity Obscurant Material and WP-2405 Proof of Concept Novel Low-toxicity Obscurant) one issue remains before a transition to industry can take place. The obscurant performance at ambient and cold conditions is not, like the hot conditions, at the high performance level when compared to hexachloroethane (HC) based obscurants. The objective of this project is therefore to improve the obscurant performance of compositions 15EM0281 and 15EM0282 at ambient temperature conditions and, if possible, at cold conditions.
At the end of SERDP project WP-2405, it was shown that the sea salt-based smoke has a very low toxicity, and is easy to produce. The obscurant performance of hot conditioned (71 ⁰C) hand grenades is at HC based obscurant levels and one of the potential candidates shows much less humidity dependence than HC smokes. Unfortunately, the obscurant performance at ambient and cold (-33 ⁰C) conditions is only equal or a little better than terephtalic acid based smokes. This needs to be improved before this very sustainable sea salt-based obscurant can be taken into service. To solve this issue the following approach will be used:
First a root cause analysis (RCA) will be performed that will investigate the cause of the low performance at cold and ambient conditions. This RCA will lead to a design of experiments (DOE) which should lead to an insight in the cause. Small scale experiments (5-15 g scale) will be used to execute the DOE, starting from the most probable causes as indicated in the RCA. At the end of this phase the potential causes of the underperformance will be identified.
In the second phase, solutions will be generated knowing the cause of the underperformance which will again be tested at small scale in a smoke box for performance at different conditions (cold, ambient, hot) and humidities. One can think of solutions based on mechanical or design modifications or changes in the chemical composition of the obscurant.
The final result of this project will be one or two obscurant candidates based on the sea salt composition that have an improved performance at ambient and, if possible, also at cold conditions. Their performance will be the input for a Go-No Go decision for a follow-on Environmental Security Technology Certification Program project where the first phase will be a technology transfer to Naval Support Activity Crane where both Naval Surface Warfare Center Crane Division and Crane Army Ammunition Activity will join forces to perform field trials at full scale hand grenades at the NSA Crane testing grounds. For this purpose personnel from both Crane divisions will be involved in the current project as consultants to TNO. In this way they can gain experience with the obscurant composition and its critical issues.
If this project is successful, the US Department of Defense will have a sustainable, visible obscurant candidate that has a reduced toxicity and a similar performance compared to HC. Several other benefits exist for the new sea salt compositions. These mixtures do not require the use of a solvent during production of the mix. This gives a very easy method of preparation, resulting in less exposure to hazardous solvents, less waste and a reduction in time required to prepare the mixture. These mixtures are also quite robust; they do not require a tight tolerance on the percentages of ingredients in order for the smoke production to be successful. Finally costs of production are estimated to be at the same level as those of the current smoke grenades.