Occasionally questions are raised about whether the antistatic fibers (contained in certain FR fabrics) eliminate static electricity, or about what can be done about static electricity.
So what is static electricity?
Static electricity refers to the build up of an electric charge on the surface of objects. The static charge remains on an object until it either bleeds off to ground or is quickly neutralized by a discharge. The effects of static electricity are familiar to most people because we can feel, hear, and even see the spark as the excess charge is neutralized when brought close to a large path to ground. The familiar phenomenon of a static ‘shock’ is caused by the neutralization of the charge. Static electricity can be considered either a nuisance in the form of the garment clinging to your body or an actual hazard from sparking in a flammable atmosphere. The main source of spark potential comes from static charges stored in the body of an ungrounded worker rather than from garments.
What causes static electricity on garments?
The generation of static electricity on clothing depends on a number of factors: the type of fabric, the relative humidity, the fabrics ability to absorb moisture, the task being performed, and the use or lack of use of grounding devices. The biggest factor is the moisture content of the fabric, as moisture allows the static charge to dissipate easier so it doesn’t build up. Under standard environmental conditions, synthetic fiber fabrics such as polyester, nylon or Nomex absorb less moisture and retain more static than natural fiber fabrics like cotton. The friction from fabric rubbing is the primary cause of static buildup. The action of donning or removing garments will generally increase the charge on the human body and provide a source for a static discharge.
Fabrics like Nomex IIIA and Protera incorporate a static dissipative fiber. This helps dissipate static charges in the fabric which reduces the risks and discomfort associated with static electricity. It also reduces the contribution of clothing to the static buildup on the human body. This fiber does not totally eliminate static, so it is always recommended that a user in a high risk environment use grounding devices like static dissipative wristlets or anklets that are available for this hazard.
Fabrics like Indura, Indura Ultra Soft and Tecasafe Plus all contain fibers which readily absorb moisture (cotton or Lyocell). This ability to absorb moisture allows the static to dissipate more easily. However in low humidity environments, the amount of available moisture may not be enough to affect the static electricity found in the garments. So wearers of these fabrics should also use grounding devices in high risk environments.
What about fabric softeners & anti static products?
Generally speaking, fabric manufacturers do not recommend using fabric softeners, dryer sheets or anti-static products that have not been tested for flammability. These products can leave a residue that may be flammable and would need to be tested. The last thing you want to do is put something flammable on a FR garment.
All fabrics have the ability to generate static electricity and FR garments are no more likely to generate static than other garments under the same conditions. The primary hazard is stored energy on the body of an ungrounded person not the fabric itself. If a wearer is in an environment where a static discharge could be hazardous, use engineering grounding controls like static dissipative wristlets or anklets or other grounding methods that are available for this hazard. And lastly, do not put on or remove garments in a hazardous atmosphere as this increases the amount of static charge on the body.