NFPA 70E Standards Hazard Risk Catagory 4 USEFUL COMBINATIONS At a minimum, NFPA 70E allows ATPV values for each individual layer to be added together when layering FR garments to reach the required ATPV rating for each hazard/risk category: (In actual testing, Layered FR garments regularly achieve higher ATPV ratings than the simple sum of their individual ratings, thanks to air gaps and other factors. But because actually quantifying this behavior requires testing and certification of each specific set of layers, It is best to simply be conservative and go with the basic sum-of-the-layers ATPV rating when evaluating layered FR work wear. One potential Example of layered FR is a worker in a pair of canvas dungarees (ATPV 15.7) and an FR twill shirt (ATPV 8.6).together with appropriate Underwear, footwear and gloves, this outfit meets HRC 2 specifications. With the addition of canvas bib overalls (ATPV 16.0) and a mid weight Sweatshirt (ATPV 21.8), this worker now surpasses HRC 3 requirements. Another worker could start with denim jeans (ATPV 25.0) and a mock Turtleneck (10.9) at HRC 2 and add the sweatshirt alone to achieve HRC 3 compliance. Another versatile clothing option for worker comfort and Standards compliance is the vest, which can be paired with FR sleeves to provide up to HRC 4 compliance in hazard areas but can be worn Unzipped in non-hazard environments for increased comfort. In regions and seasons with rapidly changing weather conditions, vests provide significant, Vests provide significant flexibility under coats, over sweat shirt, or over shirt to combine protection with comfort throughout the day. Consist of following layers: 1st layer: 205 GMS Nomex 2nd layer: 170GMS Nomex Non Woven Fabric 3rd layer: 280GMS 100%Cotton Fire Retardant Arc Rating 39 cal/cm protection FABRIC FEATURES: DuPont Nomex Aramid (93% Nomex®-5% Kevlar®-2% Carbon). CHARACTERISTICS: Inherently flame resistant anti-static fabric engineered to reduce nuisance static. Self-extinguishing, will not ignite, melt, drip or burn. These characteristics Make Nomex an exceptional all around fabric for application such as petroleum refining, petrochemical, fire service, and gas and electric utilities. IMPORTANT: NFPA 70E does not have a hazard risk category above 40 cal/Cm². Working on levels above this rating should be avoided because of the blast hazards caused by arc flash.