When most of us realize that we’re overdressed for the weather, we can simply take off that extra jacket or whatnot that’s causing us to overheat. Police officers, however, don’t have the option of taking off their bulletproof vests ... and those vests aren’t exactly known for being lightweight and breathable. Fortunately, a team from Swiss research institution Empa has developed just the thing for those hot cops – an air-conditioned ballistic vest.

The vest utilizes a version of Empa’s existing Coolpad technology, which was first designed for use in the field of medicine. The cool pad itself is a thin, flexible water-filled pouch, located inside the garment. It’s made of a membrane which the water is able to gradually evaporate through, cooling the air around it as it does so. The effect is enhanced by a miniature fan that blows air out through a fabric spacer located behind the pad, helping to carry the moist, cooling air across the wearer’s body.

There were several challenges involved in adapting the technology for use in the vest, which is intended to be worn underneath an officer’s shirt.

First of all, the spacer had to be stiff enough to maintain its structure while under pressure, while still remaining comfortable to the user. The mechanical stresses of the vest also proved to be too much for the regular cool pads, which frequently leaked. This was addressed by creating stronger membranes, using diode laser welding technology. The new pads also feature a higher evaporation rate, allowing for a more pronounced cooling effect.

The Coolpad membrane inside Empa's air-conditioned bulletproof vest

Additionally, there were no commercially-available fans small enough to fit into the vest. The team therefore built their own – each vest contains two of the fans, which in turn contain their own battery and electronics packs. One charge should keep them running for three to four hours.

In order to keep things simple, the cool pad can be refilled with water at a portable filling station, via a quick-release fastener. At the same time, the two fans can be quickly and easily exchanged for others with freshly-charged batteries.

One of the replaceable fan units

Although other cooling ballistic vests do already exist, Empa claims that its model is lighter and does a better job at cooling than any other. The garment has been tested in warm weather by the Zürich City police force, which reportedly gave it good reviews. It is now on its way to commercial production, with the help of business partner Unico Swiss Tex. Other Coolpad-equipped items, such as jackets, camouflage suits and rucksacks, are also in development.

Source: Empa

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