Static Spark Generation Question
We have a process where we are spot-treating a fabric surface with MEK to remove any residues. During use, the MEK is stored in a standard metal splash can (such as a McMaster-Carr 4487T76) next to the operator and the operator applies the MEK using a wad of cheesecloth, typicall while sitting on the fabric -- the pieces can get quite large.
Unfortunately, during the winter months, we tend to have a problem: the MEK in the dish of the splash can ignite with a static spark. Understandably, this makes people unhappy. We tend to have 1 fire each winter for the past several years and want to make them stop. We've tried anti-static heel straps and they wear out. We know that some of the operators use dryer sheets or static guard while others don't, but we can neither mandate nor provide either of those. We also have a few other initiatives in the planning stages.
With all that said, I have given the task of evaluating one of these initiatives, which involves grounding the operator to the can. In order to evaluate the idea, we need to see if we can generate a spark to the can from a person in the two cases: bonded to the can and free-roaming. Since the fires are such low-occurrence high-consequence events, we need to make sure that any solution really is a solution. We've tried several times, but just are not able to reliably generate a spark or even enough surface charge to interest the static charge detector that we have.Does anyone have any suggestions for how to reliably generate a static spark from a person to our empty metal can?
Bill
What about a flame-proof metal gauze over the spout of the container? The MEK will be fine enough to pass through the mesh, the flame should not travel back to the fluid.
Flame arresting mesh is used with gas torches and Hydrogen generators. Not sure where to point you to get the stuff, but preventing the flame going backwards to the supply seems like a better idea than de-sparking an operator.
The part number you gave is for the plastic can they sell. Thinking it'd be a lot easier to generate static with cloth running over a plastic can? Either of those units should already have the screens in them. We use the metal ones here at work and have never had a fire from them (knock on wood...) but then again we don't use the MEK much anymore either.
Also wonder... is this cleaning taking place directly on the floor? Just thinking the vapors will collect on the floor and make for a fireball begging to happen. Possibly happens in the winter due to lack of ventilation as much or more so than dry air and static? In the summer fans blowing and doors open... Winter closed up and keeping warm?
Another consideration...
You might want to consider some security cameras located where these fires tend to happen. Not saying anyone's tossing matches around but given the rarity of occurrence it has me wondering if it is indeed static or something else. Should this happen again you might be able to review a tape and see where the ignition source came from. Like maybe a smoke hanging out of someone's mouth? Maybe once a year somebody decides the no-smoking thing is B.S. and fires one up? Maybe somebody combing their dry hair with a plastic comb? Or maybe somebody wanted to leave early that day. Sick as that sounds... some folks could care less about other peoples things and will do stupid things thinking that they're benefiting from them.
oops... Your question was... "Does anyone have any suggestions for how to reliably generate a static spark from a person to our empty metal can?"
Here's what I used to do to my sisters when I was a kid...
Take off your shoes but leave on some clean dry socks and shuffle around on a carpeted floor then reach for the can. Or maybe wash your hair with Coast deodorant soap and don't use anything else. Grab a balloon and rub it on your head. Hold balloon close to the can.
Hi Bill,
Welcome to the forum.
I'm the OSHA safety officer here at my company...I'm not sure what environment you are working in. Here are some of my recommendations. We use a similar chemical that is just as nasty.
Get away from the spark generation..."You'll put an eye out with that"...A Christmas Story
Remove ALL metal from the process. Try to store MEK in a Polypropylene container. www.usplastics.com
You may even find a pump sprayer to help apply the MEK to the spot.
Get away from the cheese cloth...google "Static Free Applicators" Tons of different tools out there.
Anti-static Nitrile gloves and a respirator for fumes should be used...this is piece of mind to the user.
The only grounding that seems feasible is a long wrist strap from the person to a known common ground. I use our compressed air lines or an electrical outlet. Always check continuity between the person and the common ground.
I hope this helps.
Mark
Whoops. You're right, that's the wrong part number. However, the difference between the McMaster can and mine is the metal body. The splash mechanism and dish are all still metal. That's one reason we havent gone with the plastic splash cans.Originally Posted by RWOLFEJR
Yes, it is, but the sheer area of the room (100' x 250') compared to the number of cans in use at any time, coupled with the ventilation in the room, make the concentration below the LEL (1.4%) at any distance more than 1 foot from the can (we measured it last week ... it's 7ppm or 7/10,000%). At the actual can, the concentration is about 1.8% right on top of the actual dish and 0.7% about 2-3 inches away to the side, so any spark that is strong enough at the dish could ignite the vapors, but the area that can cause ignition due to vapor density is quite small.Also wonder... is this cleaning taking place directly on the floor? Just thinking the vapors will collect on the floor and make for a fireball begging to happen. Possibly happens in the winter due to lack of ventilation as much or more so than dry air and static? In the summer fans blowing and doors open... Winter closed up and keeping warm?
We have done after-incident investigations, complete with witnesses and supervisors. None of our fires have been from anything but static discharges. Prior to the last one, the operator had just taken off her heavy wool sweater and walked over to the work area.Another consideration...
You might want to consider some security cameras located where these fires tend to happen. Not saying anyone's tossing matches around but given the rarity of occurrence it has me wondering if it is indeed static or something else. Should this happen again you might be able to review a tape and see where the ignition source came from. Like maybe a smoke hanging out of someone's mouth? Maybe once a year somebody decides the no-smoking thing is B.S. and fires one up? Maybe somebody combing their dry hair with a plastic comb? Or maybe somebody wanted to leave early that day. Sick as that sounds... some folks could care less about other peoples things and will do stupid things thinking that they're benefiting from them.
Not a problem. We actually tried the feet shuffling and couldn't get a discharge on a day with 28% RH. We also tried putting on and taking off fleece sweatshirts repeatedly until we got the little sparks, but couldn't get a discharge strong enough to feel, see, or hear (ie - no discharge). We actually have some balloons on-site and we can try that.
Thanks, Mark. We hadn't really looked at the applicator cloths, but I will investigate that next. We had though about grounding the operator or the can to the building (or both), but that seemed like it could make things even worse if there was a mental hiccup on the wrong person's part by giving the charge a straight path to ground rather than just to the metal can. Of course, once we get the spark, the MEK lights and it doesn't really matter how strong it is (until the spark hurts the person, that is).
I think you're probably right and we're on the wrong path. If we remove the metal and replace it with plastic, we can eliminate the spark which is the ignition source in the first place. We can probably even cut down on the amount of MEK wasted to evaporation before use. Of course, we're trying to remove the solvents from the process altogether, but that'll take 2-4 years.
Thank you to everyone who replied to this question. We've decided to move forward with completely plastic MEK bottles as long as our operators don't have any issues with them, so we can abandon our unreliable spark-generation efforts.
That's the way to go Bill. If you need anymore help just drop a line.
Happy Holidays!!
Mark
I agree with Bill, Polypropylene is a good choice to resistance to MEK. Possibly HDPE may work as well.
The polypropylene chemical resistance shows an excellent rating on the chemical resistance chart I just saw.
polypropylene.pdf
But would stick to polypro over anything else for higher temperatures, if that is a consideration.
Last edited by Kelly_Bramble; 01-12-2016 at 09:39 AM.
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