Explosion: Forklifts 2

[macfa1]

Hi all,

very interesting problem here: We have forklifts on our site that have to Explosion Proof, I.e Earthed so that no spark occurs, which could potentially cause an explosion.

The forklifts are constantly driving over oil patches and after about 3-4 months, so much oil is soaked up by the tires that they are no longer deemed “Earthed”.

Because of this we have to machine off a layer off the tires in order for them to be “Earthed” and we can only do this a maximum of 2 times, because the tires would be too weak to take any more machining.

We have tried and tried to come up with ideas to keep the forklifts earthed. We can´t do anything about the oil, so we need to come up with a solution to keep the forklifts earthed.

One solution was to have a copper wire hanging from the back or front of the forklift (like a lot of cars use to have in the 80´s to “supposedly” stop the passengers from becoming travel sick). However, most people thought that the wire itself might cause sparks itself or that a clump of oil would build up at the end of the copper wire and would itself become unearthed.

Do any of you guys have any ingenious solutions.

Would be greatly appreciated.

Thanks in advance,

Alan

 

[saxon]

BTW, After you've cleaned up the spills and residues, go after the cause of spills/leaks. Whether it be leaking piping, open drum/container transfer problems, or other required process changes that will eliminate leaks and spills. Also implement a plant wide Spill/Leak Containment, Control & Counter Measures Plan. I'm surprised you don't have one of these in place already.

saxon

 

[unclesyd]

If you are worried about the chain or grounding strap bouncing off the floor put one on each end of the truck. The truck would almost have to become air borne to clear both straps.

 

[macfa1]

"Saxon" - Unfortunately I'm the second in command of the mechanical workshops and have no say in how the polyethylene plants should be run,i.e. cleaning regime! Of course I've suggested to the engineering team that they should do something about the oil/dirt, but it's like talking to a brick wall because the polyethylene industry has no money at the moment and savings have to be made somewhere!!!

But I do have control over the forklifts, and have responsibility to keep my men out of danger!

Bit dramatic with the BBQ - Just cleared 17million man-hours without a day away from work, which I think is pretty sweet, considering some of the things I've seen in my time, especially in the States - Houston to be exact

Thanks for the tip anyways!

 

[smckennz]

Personally I cant see anything wrong with the nonsparking brush, drag chain or cable.

However if there is objection to sliding contact or dragging things about, how about rolling contact on the existing wheels?

Think about this:

A conductive band (e.g. a metal band 1" wide by 1" thick) with an O.D. slightly (say 0.5" to 1&quot larger than the existing rubber wheels. The band is attached to the existing wheel hub (metal) using say six soft coil springs.The band would be located parallel to and either inboard or outboard of one or more of the existing rubber wheels, with a small gap between band and wheel face. When the vehicle is resting on the ground the band centre will higher than the wheel centre by half the diameter difference. The coil spring compression should ensure reasonable contact with the ground, but by using soft springs, grip of the rubber tyres will not be sacrificed. The conduction path would be from the existing hub, through the spring (or parallel connecting braids if thought necessary), through the band and into the floor.
There are about a million improvements that could be suggested (e.g. driving dogs guide plates, rubber instead of springs, number of wheels needing this etc), but you are looking for an idea, so hopefully its well enough described for you to get the picture.

Will it work any better? I doubt it, but it could be made to look good, which should keep the boys happy.

Let me know if you understand the description.

Cheers

Steve

 

[ornerynorsk]

It doesn't matter how clean the plant is, the man needs to comply with applicable safety standards.

 

[RiBeneke]

Maybe this is a stupid question, but have you actually measured the loss of conductivity in the tyres as a result of the oil-soaking? A simple ohm-meter with the forklift tyre standing on a metal plate would give answers. Maybe you are not losing much conductivity.

 

[rmw]

This thread has a lot of thoughtful and seriousl ideas by engineering professionals.

Now, while we are at our computers, discussing safety, designing safe processes, etc., what are the guys in the warehouse doing with the forklifts?

For a glance, go to

http://www.cargolaw.com,

and in the right hand column, under "important features," find "singles only". Click there, and scroll down under the yellow header, and find in "2003, the first half" a feature titled "Safety lift June 2003"

My comment, we as engineering professionals can design all the safety into the process that we want to, but if the idiots in the warehouse are going to committ unsafe acts, we can never win.

By the way, while you are at the site, look at the photo immediately above the one I sent you to, entitled "F-22 Stealth Fighter Bomber." Enjoy!!!

rmw

 

[rmw]

And, by the way, I found this interesting website while looking for information on the M/V Stellmare, the vessel that rolled over in the Hudson River in the USA while loading electrical generators.

If you are a Power Oriented engineer, by all means see "no right turn-Oct 2002" also under "important features" in the right hand column, except click on "photo Gallery of transport loss" and look down past the yellow background area to the white background part.

We as engineers cannot design around some of the blunders that are to be found on this site, no matter how hard we try, but that does not mean we should quit trying.

rmw