Tuesday, 15 May 2012

Air-conditioned protective clothing for police, first responders, soldiers

Bullet-proof vests made of Kevlar; the material holds off bullets, but it also impenetrable to water vapor; police personnel who must wear such gear under their uniforms sweat profusely when the weather is warm; researchers develop a “smart,” air-conditioned protective vest, and the smart cooling technology is also suitable for protective suits worn over normal clothing, uniform jackets, camouflage suits

Functional sportswear is taken for granted these days. It is unexceptional for a sports jacket, for instance, to be both waterproof and breathable. In the case of working clothes, the functionality is mostly restricted to personal protection against fire, sharp objects, chemicals, and so on, with wearer comfort (mostly) not being significance top priority.

Bullet-proof vests made of Kevlar, as their name suggests, hold off bullets but they are also impenetrable to water vapor. Thus, police personnel who must wear such gear under their uniforms sweat profusely when the weather is warm. A situation which is merely uncomfortable when working in the office negatively affects the physical performance of police officers on duty.

An EMPA release reports that researchers at the Swiss Federal Laboratories for Materials Science and Technology, or EMPA (for Eidgenössische Materialprüfungs- und Forschungsanstalt), together with EMPA’s industrial partners, have developed a “smart” protective vest with an integrated cooling system based on the cool-pad technology, originally designed for use in cooling garments for medical applications. The cool pads built into the vest are filled with water, which is allowed to evaporate through the membrane, cooling down its surroundings. A mini fan blows air though a fabric spacer behind the pad, providing further cooling.

The researchers say that integrating such an A/C into a garment proved to be tricky. It required a novel fabric spacer, which was stable under pressure yet also flexible and soft to the touch, and which offered very little resistance to air flow. A suitable spacer was developed together with Swiss textile manufacturer Eschler. There were also no fans on the market which were small enough to be built into the vest; so EMPA engineers designed a miniaturized version themselves. Two units including batteries and control electronics now provide the cooling air circulation in the vest.

The cool pads used until then were also unsatisfactory, since in the protective vest, when the fans were mechanically stressed they frequently leaked water. A new technique for welding the ultra-thin pad membranes using diode lasers proved more reliable than the conventional method, with the seam remaining soft and flexible. In addition, the EMPA specialists were able to increase the evaporation rate and, therefore, the cooling ability.

This, however, was not all. In order to simplify refilling the cool pads with water, the researchers developed a portable filling station that can be attached to the vest with a quick-release fastener. During the same “pit stop,” the mini fans can be exchanged for those with freshly charged batteries. The vest is then ready once again for three to four hours of duty.

The release notes that comparative measurements show that the new vest is significantly lighter and also cools much better than systems currently on the market. In practical use, too, the vest has proven its worth.
Staff of the Zürich City police force tested the vest over several warm summer days, and the police officers who used it found it helpful.

The first small series of the novel under-uniform protective vest will be produced in the near future by project partner Unico swiss tex GmbH.

EMPA says that the smart cooling technology is also suitable for protective suits worn over normal clothing, uniform jackets, camouflage suits, and even for rucksacks.

Source: Homeland Security News Wire

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