Workers in various industries are facing challenging environments in their daily job, dealing with a wide range of on-the-job thermal hazards, the most severe being the arc flash. In this article, we will define an arc flash and the consequences it can have as well as explain how wearing the right PPE can make the difference, focusing on the raw material and the fabric technology.
An electric arc is a continuous electric discharge of high current between conductors, generating bright light and intensive heat. With a generated heat flux that could be greater than 50-100 cal/cm2, an arc fault can cause different types of hazardous impacts, such as: thermal impact, molten metal splashes, heat up to 19000°C. For fabrics, those impacts translate into high heat transfer, risk of flammability and break-open. If these risks are not mitigated and managed properly, according to the results of a risk analysis, the selection of PPE can lead to severe injuries for the workers.
Double-faced fabric: a key for arc flash enhanced protection
One of the negative impacts of an arc flash is a skin burn caused by energy generated during the incident. The level of burn injuries can be increased by the clothing igniting. That’s why preventing the clothing from igniting is a starting point when developing a fabric for arc flash protection. As a meta-aramid fibre, Nomex® is inherently flame-resistant. A key factor in the protection it provides, is its ability to carbonize and thicken when exposed to intense heat, increasing the protective barrier between the heat source and the wearer’s skin, therefore minimizing burn injury level.
In addition to the composition, fabric construction can also positively affect the level of performance. The innovative patented technology of double-faced fabric enables more comfortable, light weight solutions with high-performing electrical arc flash and thermal protection. To illustrate this improvement, we compare two different solutions from DuPontTM, having the same composition (93% Nomex®/5% Kevlar®/2% antistatic) and weight, but different weave structures:
- Nomex® Comfort, 225 g/m², conventional weave construction
- Nomex® Xtreme Arc, 220 g/m², special double weave construction
Protective performances are compared by using the following test methods:
- NFPA 1971, clause 8.10: determination of heat transmission on exposure to both flame and radiant heat
- IEC 61482-1-1: determination of the arc rating of flame-resistant materials for clothing
This data demonstrates how the double-faced construction provides superior electric arc flash and thermal protection compare to conventional weave, at an equivalent weight. The fabric face which is exposed to heat shrinks and forms air bubbles between layers. These bubbles create a critical, additional layer of insulation that delivers increased protective performance in arc flash and flash fire situations.
In conclusion, arc flash presents a very serious hazard for industrial workers, because of the risk of severe burn injuries caused by intensive heat and molten metal splashes generated during these types of incidents. Aramid material like Nomex® will provide a level of protection that cannot be washed or worn out. In addition, the double-faced technology used in DuPontTM Nomex® Xtreme Arc is a breakthrough in arc flash protection as it offers a lightweight and comfortable solution with significantly superior protection.