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    Keeping Your Cool: The Personal Thermal Management System

    Warfighter wearing PTMS

    Courtesy Photo | Warfighter wearing the PTMS at the Chemical and Biological Operational Analysis event...... read more read more

    FORT BELVOIR, VA, UNITED STATES

    12.13.2019

    Courtesy Story

    Defense Threat Reduction Agency's Chemical and Biological Technologies Department

    Impermeable protective suits prevent chemical, biological, radiological, and nuclear (CBRN) hazards from touching skin, but they retain body heat, which has been a concern of the DoD for some time. The heat retention makes the warfighter vulnerable to heat exhaustion or heat stroke. To avoid thermal injury, warfighters limit their time wearing impermeable protective suits when managing a CBRN event, but this approach lengthens the duration of the mission. Therefore, industry researchers, supported by the Defense Threat Reduction Agency’s Chemical and Biological Technologies Department (DTRA CB), have developed the Personal Thermal Management System (PTMS) to actively cool warfighters wearing impermeable protective suits.

    The PTMS comprises a cooling vest and a miniature refrigeration unit. Warfighters wear the cooling vest directly next to their skin; the refrigeration unit attaches to the suit’s exterior. Powered either by a vehicle or a standard military battery, the PTMS circulates cooled water throughout the vest to keep the warfighter at a comfortable room temperature of 72 degrees Fahrenheit — even in desert heat (125 degrees Fahrenheit).

    DTRA CB is supporting further testing of PTMS, including its integration with other CBRN science and technology solutions. The new cooling system will become part of the Tactical All-Hazards Ensemble (TacHazE), which is a new Level A protective suit that has low profile, bulk, and weight. In August 2019, at the Chemical and Biological Operational Analysis at Camp Dawson, West Virginia, researchers and warfighters assessed the PTMS in a current Level A suit and in the TacHazE. Although improvements are needed, such as creating cooling shorts to accompany the vest for greater skin contact, the PTMS performed well.

    The concept of a cooling vest is not new, but existing off-the-shelf personal cooling systems are incompatible with CBRN protective suits. Current systems pose the following three challenges:


    1. They are neither powerful enough to cool the warfighter for up to four hours nor maintain energy efficiency when on battery power.

    2. Their ability to transfer coolant from inside the suit to its outside, through an opening in the suit, risks exposing the warfighter to CBRN hazards.

    3. They do not respond to the warfighter’s cooling needs, which vary by mission-related activity and the operating environment.



    The PTMS overcomes all three challenges. To address the first challenge, the PTMS is lightweight, cools regardless of the warfighter’s physical position (standing, sitting, etc.), and is energy efficient. The system uses the same vapor-compression technology that a standard household refrigerator uses. When the system operates on batteries, 40 percent to 60 percent of the power goes toward cooling the warfighter, which makes the PTMS more energy efficient than other cooling systems available on the market. A single battery charge allows the PTMS to operate for four hours. Because the battery pack is designed to hang outside the protective suit, a warfighter can easily replace a used battery and remain on the mission longer.

    To conquer the second challenge, the PTMS has a closed “liquid penetrator” valve that allows coolant to flow through the suit. The valve also has a hands-free, breakaway feature that separates it from the warfighter during an emergency. To ensure that the valve prevents CBRN hazards from entering the suit, researchers rigorously and successfully leak-tested the valve against performance standards set by ASTM International.

    To prevail over the third engineering challenge, PTMS responds to the warfighter’s cooling needs. A wireless temperature sensor sits on the warfighter’s skin to monitor thermal changes in real time. An increase in skin temperature indicates an increase in the core body temperature, so when the skin temperature rises above 93 degrees Fahrenheit, the PTMS works harder to pump colder water. The colder water lowers skin temperature, which then lowers the core body temperature.

    Finally, warfighters have a safe and energy-efficient cooling system to accompany their impermeable protective suits. The PTMS cools warfighters while they manage CBRN hazards, reducing the concern for thermal injury. Wearing protective suits for a longer period of time when mitigating CBRN hazards enables an efficient completion of decontamination efforts and a faster return to the mission.

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    NEWS INFO

    Date Taken: 12.13.2019
    Date Posted: 12.13.2019 11:29
    Story ID: 355591
    Location: FORT BELVOIR, VA, US
    Web Views: 403
    Downloads: 1

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    Cooling vest, thermal management unit, and liquid penetrator valve
    Warfighter wearing PTMS

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    chemical
    biological
    radiological
    CBRN
    and nuclear hazard
    PTMS
    impermeable protective suit
    wearable cooling system
    Personal Thermal Management System

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