A Portable Burn Pan for the Disposal of Excess Propellants

Michael Walsh P.E. | USA CRREL

ER-201323

Objectives of the Demonstration

Training with munitions will result in the deposition of energetics on ranges. Artillery training with mortars and howitzers adds a unique component to potential range contamination. Munitions are issued with a full complement of propellant charges that are varied according to the state of the equipment and mission. Excess propellant is burned on site as part of the training mission. Research under SERDP project ER-1481 established that up to 20% of the propellant in these burns may not burn properly or at all, contaminating the burn point where the training occurred. The US Army Cold Regions Research and Engineering Laboratory (CRREL) developed and tested a prototype portable burn pan under SERDP that enabled artillery batteries to conduct training burns while minimizing the environmental impact of the activity. The main objectives of the project demonstration were to validate the portable burn pan technology and to transfer the technology to the end users. Specific objectives were established to determine if the burn pan would be an effective alternative to burning propellant on the ground or in antiquated fixed burn pans. 

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Technology Description

The portable burn pan is designed for the expedient field disposal of excess howitzer and mortar propellants. The pan in its current configuration is approximately 1-m wide by 2-m long. It has evolved over the last seven years, the original prototype pan and the second prototype built and tested under SERDP project ER-1481.

The system is composed of only three parts, an aluminum base, a stainless steel false bottom, and a removable bonnet that fits on top of the pan. The base elevates the system off the ground while partially containing the burn. The base contains a removable stainless steel false bottom that protects the structure from the high heat of deflagration. The base and false bottom combination provides a dry, semi‚Äźenclosed platform that separates the burning propellant charges from the ground surface and contain the residues from the propellant burn (ash) for easy removal and treatment, if necessary. A removable, retractable ignition trough passes through the pan and extends into the false bottom to enable safe initiation of the propellant burn. The perforated bonnet partially contains the burn, limiting ejection of large unburned material such as charge bags that loft during the deflagration process. The device is compact enough to transport in a standard small military truck and light enough to be handled by four or fewer personnel. The target propellant charge load is in the 120 kg range for a full-size burn pan, although it is recommended limiting the charge load to 90 kg if there is vegetation nearby. The loading dimensions of the false bottom of the pan are 0.9 x 1.9 m.

A second, smaller burn pan, designed for use with mortar training units, was also demonstrated. The smaller size of the unit allows easier movement and is built to accept the smaller charges encountered during mortar unit training. The mortar unit training system burn pan is designed for charge loads of less than 50 kg/burn. The loading dimensions are 0.9 x 1.0 m.

ER_201323_VPO_graphic

Figure i. Assembly drawing of the Howitzer Unit Training System Burn Pan

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Demonstration Results

The original testing of the propellant burns, fixed burn pans, and portable burn pans occurred prior to this project under SERDP project ER-1481 and US Army funded research. Under this project, three technology demonstrations occurred, all of which were highly successful. Two tests were conducted with the Howitzer Unit Training System and one with the Mortar Unit Training System. The final demonstration of the technology entailed the training unit burning over 450 kg of propellant over six burns. After all tests, both the training units and the facility mangers requested burn pans.

Quantitative performance objectives were a 99.9% reduction of the combustible mass of the propellant charges, recovery of 0.01% or less of the energetics and 10% or less of the lead (if any) outside the pan after a burn, and a turnaround time of less than 15 minutes between burns. The target mass for the large burn pan was <130 kg with a 120 kg burn capacity and <80 kg mass for the smaller version with a 50 kg burn capacity. All objectives were met for the large burn pan. The propellant mass for small burn pan test was insufficient to test the burn capacity objective. Qualitative objectives included ease of use, acceptance by Range and Environmental managers, and the ability to integrate the burn pan into artillery training. All these objectives were met.

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Implementation Issues

The CRREL portable propellant burn pan training system has been enthusiastically accepted by all who have participated in the project demonstration. Environmental and Range officials at all three installations not only asked to keep the burn pans tested at their facilities but asked if they could acquire additional units. The training units also have enthusiastically embraced the concept, with soldiers and officers all asking if they could continue using the burn pans after the completion of the demonstrations. The burn pans have been integrated into the Standard Operating Procedures of the three test installations and the ARNG Bureau has issued Best Management Practices guidance on using the burn pan at all installations that conduct artillery training. The CRREL portable burn pan training devices will allow the DoD to better train their soldiers while reducing the environmental impact of that training.

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