Fire resistance of PPE

We had an arc flash incident a couple of months ago, and thankfully the employee was wearing his PPE, which probably saved his eyes, but still came out with second and third degree burns. The interesting thing is, the jacket continued to burn even after the event, and had to be put out with the PPE jacket of the second employee who was out of range of the blast. My concern is why it kept burning, there is only about 20-30% of the jacket left. My understanding is that it will burn, but will self extinguish. Is it normal to keep burning? The jacket had not been washed since new, and was not contaminated with any flammable liquids or grease. I beleive it has the spray on retardent, not the woven in type. It was bought from a reputable supplier, so we don't think it is counterfeit PPE. (The shirt underneath was our standard issue all cotton)

There is always an ignition risk, Hugh should jump in here as he does all the testing of this stuff. What was the material being used? Can you post a photo of your PPE and label?

We have sent it off to a lab to see what happened, I will see if HR has any pictures I can post. I know that it is the spray on retardent, but I did not catch the manufacture, we have bought from several vendors over the years, but this one came from Grainger. it is 11 cal.

I was not asking for photos of the damaged one, HR likely will not release those, just a photo of the tag of a similar one.

Continued burning

Several things could have happened.

1. There are no legitimate "spray on FR" treatments. See if the jacket had ASTM F1506 in the label. If not, it is really not arc rated.

2. Did the t-shirt ignite? This will often keep arc rated garments burning. I've seen a few fatalities from this.

3. Not washing is also not your friend. Always wash a garment before wearing. Sizing (starch) is combustible but not usually life threatening.

4. Dealers who are large carry LOTS of things and don't mean it wasn't an "on the edge material". The larger they are the less the frontline folks know.

My bet at this point is cotton undergarment ignition BUT no way to tell with this much info.

Here is what we ordered, http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=3YA92&op=search&Ntt=3YA92&N=0&sst=subset It says it has flame resistant thread, so maybe its not spray on.

Here is the picture if I can get the file small enough.

No Issue

The energy level was definitely above 11 cal/cm2 (the rating of the material). This material become quite brittle and will afterflame at about 25-40 cal/cm2. It is a good quality material. I do tons of testing on this and it is the most common fabric on the market.

I'm even more convinced this was a t-shirt ignition.

Do you know the energy level calculated at the fault location?

Looks like this work place needs more protection for this job condition.

I am with Hugh, quality material from Salisbury, > 11cal exposure. Was this equipment that had an arc flash study label or just using the tables. Either way something is not right about the analysis.

Glad to know it's quality material, as far as the t-shirt ignition, I can see that as a possibility. I do not know what the energy level was, this accident happened on the same day I was taking training at Georgia Tech to become safety coordinator. I too have a suspicion that the energy level was higher than what it was rated for. The employee was doing something against company policy when it happened. Now that this has happened, he will probably be the safest employee we have. He definetly learned his lesson the hard way.

It definitely sounds like the 100% cotton t-shirt may have been the source of the problem. Have you figured out what the problem was with the Salisbury 11 cal/cm2 jacket & pants?

It would be interesting to know what the actual exposure level was as to an arc flash analysis. From what I understand the fabric that Salisbury uses is the Indura Ultra Soft which is top of the line. If the exposure level was very high I wonder if this could be a reason the weaken the fabric enough for it to continue to burn. Possibly the jacket was damaged more from the initial blast then previously thought.

I am just putting these suggestions out there for comments (Hugh)?