black t shirt|
After a 15 years of arc flash testing, investigations and replications with electric arcs, a few lessons have emerged as critical in Personal Protection Equipment (PPE) programs:
1. PPE has to be worn?
Whether it’s because of a lack of training the importance or a policy saying, “Wear it when it’s needed,” or if the right garment wasn’t picked for the job. PPE is no good if it isn’t worn. Most accidents happen when the worker believes they need no protection. If the employer buys the the least expensive garments they will have poor compliance to their policy. Another reason why PPE isn’t worn is that the company believes more is better and provides heavy, uncomfortable PPE. If it is worn all the time, less can be best. The greatest difference in clothing for the arc flash is the difference between non-FR and FR. To be concerned about the difference between a 100 cal/cm² suit and a 40 cal/cm² suit is to miss the point. Many companies will provide 100 cal/cm² suits, which are not worn. It is best to have a worker in an 8 cal/cm² shirt and an arc rated jean than in 100% cotton because it arc rated clothing will not ignite.
Cheaper suits are often heavier but if workers are wearing them for a short time they are a good value. If workers are working in arc flash hoods more than 20 minutes per day consider a lightweight suit, which is at least 40 cal/cm². Some of the 40 cal/cm² suits are one half the weight of others.Adding venting to a hood may add $200 to the cost of the hood but it can make a huge difference in worker comfort. Field trial the options choices to see real world performance.Considering cost and comfort increases compliance.
2. Flame Resistant in the label doesn’t mean anything.
FR Acrylic, nylon and polyester are not really flame resistant for practical purposes. These materials should use another name because “flame resistant” by definition gives the user the wrong impression. They may be fine for a worker who has little or no flame exposure but they are dangerous in electric arc and flash fire conditions where these products melt into the skin. Products you choose should meet the right standards.
Here are the standards to specify:
– Clothing — ASTM F1506 or IEC 61482
– Rainwear — ASTM F1891
– Hoods and Face Shields — ASTM F2178
– Fall Protection Exposed to Electric Arc — ASTM F887
– Gloves — ASTM D120
– Flash Fire Clothing — NFPA 2112, CGSB 155.20
3. Using FR Rainwear rather than Arc-Rated Rainwear.
Make sure you have the right rainwear. Only rainwear that meets ASTM F1891, F2733, or NFPA 2112 will not melt in arc or flash fire conditions. Arc-rated rainwear is usually built on DuPont’s Nomex® or Kevlar® or a blend. Nylon or polyester, even if labeled “FR” are not acceptable in rainwear exposed to arc flash or flash fire.
4. Using non-FR winter wear over FR and thinking you are protected.
An FR shirt under a flammable jacket will not protect. Winterwear that does not meet ASTM F1506 is dangerous in an arc flash. In two accidents I have investigated, a non-FR winter jacket burned workers under FR clothing over 50% of their body. Many winter liners are now available which keep workers warm and protected. Try Westex’s Indura(TM) ModaQuilt(TM) or the the new 3M FR Thinsulate or many other options which do not melt and have F1506 testing.
5. No training on undergarments.
In order the meet the NFPA 70E standard, workers are required to wear non-melting natural fiber undergarments or arc rated underwear. Flame resistant bras and other undergarments are available. Avoid any wickable material which can melt. These materials should not be worn as underwear in arc flash or flash fire exposures. Plain cotton, wool and silk are all good options for winter undergarments or arc rated t-shirts made from materials like Indura UltraSoft® Knits, Springfield’s FireWear®, ITI’s EMC(TM), SSM’s ProC FR(TM), DRIFIRE, FR Wickers wool or various Nomex® Knits are acceptable.
Simplifying an arc flash PPE program by using daily wear with 8 cal/cm² protection and adding an arc flash rainsuit, or an additional coverall or a lightweight flash suit with a flash suit hood makes a well rounded program easier to live with and work in.
write by Isolde