Cell Phones and ESD

You wrote: "The "Gender" connection relates to the wearing of "Synthetic" material-based UNDERWEAR and therin was the cause of the static buildup and the ESD."

Sounds like interesting, if not amusing stuff. Do you have a link to proves this?

I remember the sparking chains. The sparks weren't from ESD, of course.

ESD is why it's now suggested that you fill your portable gas container with it sitting on the ground, and the gas nozzle in contact with it as you fill. Less sparks = less explosions.

I was surprised that a recent new hire (college grad) had NO exposure to ESD rules or effects. (I didn't either, but that was 30 years ago.) Don't they teach this stuff in school?

Myth Busters ran an episode on this and proved that the cellphones themselves were not to blame.

People can pick up a static charge while in the car with all it's leather, plastic and vinyl parts. If a person pulls into a gas station, gets out and neglects to touch the car's metal body, the charge remains on him. When he starts pumping the fuel (self-service stations), he could cause a spark to jump and ignite the fumes coming out of the gas tank as it's being filled.

The thing to do (according to the expert) in case a fire does occur, is to not panic and just release the nozzle's trigger. Don't try to pull the nozzle out (pulling it out only spreads the fire). The fire will be limited to the gas tank's port and easily put out with a fire extinguisher.

Any act of excess movement on a given surface will generate ESD. The fact that women are more likely to be injured in a fire at a surface station could be traced to the different fabric in ones underwear,but that is just a minor factor. As stated above, excess movement of any kind will regenerate ESD reguardless of the gender. Men have a habit of staying with the gas nozzle thus cancelling out any ESD generated. Women ,on the other hand, have a habit of REENTERING the vehicle after the pum[ing process in started, thus rebuilding up a ESD charge. James

In the UK the locking type petrol nozzles were banned so you have to hold the pump trigger all the time that you are filling the car. I can't remember ever hearing of a petrol pump fire over here. Would it not make sense for the pump manufacturers to ground the nozzle so that the operator discharges any static as soon as they pick it up?

I think the problem lies in the leaving of the pump and re-entering the car. The person comes back to the grounded pump, yanks it out, and then spark.

About the myth busters episode... I completely agree that a cell phone is 99.9999% not likely to start a fire (assuming you are not fueling inside or drop the phone in the stream). There is that 0.0001% chance though. I am surprised that they don't put a disclaimer on their episode saying they don't guarantee any myth. If some idiot were to drop their old cell with some sort of internal short into the stream and they were injured.... it's sad but they may have a case. Claiming that Mythbusters told them it was impossible. I mean... if a person can sue McDonalds for spilling coffee on theirselves.

If I recall, correctly about the MC Donalds law suit the defendants (MC Donald's) got off pretty cheap thanks to a judge who reduced the punitve damge award given by the jury from $2.9 million to $600,000. Coffee tast better boiling hot. There is a federal law as to how hot a person in the comfort of there home can make the coffee but commercial businesses are exempt from that law.

RED DAWG

I think the nozzles are grounded, but they usually have a plastic sleeve on them to make them more comfortable. They should probably switch to a conductive plastic sleeve. That's what happens when you don't let electrical engineers design everything.

As for the locking mechanism - you UK and AU types underestimate the laziness of the American public. Better to burn than have to hold that nozzle.

It's not laziness, it's multitasking. While the tank is filling, the windows and headlights can be cleaned. Not all gas stations have the catch on the handle. In that case, one has to spend more time at the pump. This can cause a back-up, so people are wasting fuel waiting in line. Also it is more likely that one will end up smelling like unleaded.

I doubt if the nozzle handle is grounded -- there would have to be a wire running up the inside of the rubber hose. It doesn't make sense either. The last thing you would want is for a car that has built up an electric charge running down the road to send a big spark to the fuel handle when you first insert it.

From the Petroleum Equipment Institute:

Q: Pump Grounding
Why not just ground the pump/hose/nozzle?

A: They already are. Or, at least, they should be. Standards call for continuity between the dispenser and refueling nozzle.

The issue here is the electrical difference of potential between the person and their vehicle. They have created a static charge between their body and their car, which may not be discharged by touching another grounded object.

I assume that the wire is in the rubber hose, a spiral type of thing that reinforces the rubber in the hose.

There's no spark involved - it would be done like ESD protection is done in electronic labs. There's not a direct low impedance path to ground, but through a resistor, so that any static charge is slowly dissipated.

I never multitask at the pump - even though I would love to be able to leave the pump and run inside to get lottery tickets, I'm afraid to trust the automatic shutoff.

And I never go to a station where I have to wait in line, except during hurricane evacuations.

That makes sense. A resistive ground, I feel safer knowing about it. Maybe one should insert the nozzle and make sure they wait a few seconds to bleed the charge on the vehicle off before pumping.

My brother spent a good part of a morning talking to a county road service technician as he replaced the clutch on the tech's service truck. The next day the service technician was on the road, trying to start a county vehicle. It was not getting fuel. Guessing the fuel line was clogged, he used compressed air to blow into the detached fuel line under the hood (without removing the tank cap). When he released the air hose from the fuel line, fuel sprayed over him, startling him, which cause him to drop the air hose, which hit the battery and shorted from positive to frame. It was fatal.

When the attendant resets the console there is a delay between the numbers resetting and the pump starting to allow time for discharge, at least in OZ.

You have attendants? Over here it's all done at the pump by the customer - but there is that annoying delay.

Only at the console inside where they take the money and sell the cigarettes.

I pay at the pump with a card - no human intervention required. Sweet. I assume you have those down there too. I have to wonder though - how do you keep the gas in the tanks, being all upside down and all?

We have a few for 24hr service that read your card at or near the pump, mostly there is a console operator and our service stations double as corner shops with bread and milk etc for sale.

Gas could be a problem, but we find petrol and diesel stay in the tank ok.

As an employee of a medical diagnostic imaging company, I can provide an example of non-synthetics causing a similar problem. We manufactured a hand-held controller as part of a nuclear imaging system. Shortly after product release we noticed that a particular IC in the controller was being replaced regularly in the repair process. We contacted several of our customers and asked for additional information. In one instance we found that a particular tech was the one 'responsible' for the failures. We sent several failed IC's for autopsy and were told the failures were due to ESD. Even though the PCB inside the controller was grounded through the braid in the cable (low impedance) we continued to have failures. We were unable to duplicate the fault at the factory. I spoke with the tech mentioned above and found that she complained about receiving a shock from the controller. She was the only one who complained of this.

I visited the site, spoke with the techs and watched them work for a day. I brought several boards for the controllers. The techs used them and the 'static tech' destroyed two. I delicately asked if she wore silk underwear and was rewarded with a blush and a "how did you know?"

I remembered the classic experiment of static experiment with silk and put it together. We fixed the problem by coating the inside of the fiberglass controller case with conductive paint and providing a low-impedance connection from the case to the shield.

Problem solved.

Wouldn't it have been simpler to paint the tech with conductive paint?

mmm - maybe "simpler" isn't the right word....

Once I was pumping gas - I had the nozzle locked and I was not paying attention. I heard what sounded like leaves blowing across the pavement. It was actually gas pouring out of my gas tank and flooding the ground under my car - the auto-release thingy had failed to stop the pump once my tank was full.

I was so surprise I almost dropped my cigarette.

When I flew for a living (and it wasn't much of a living), our operations specs, issued by the FAA, prohibited the wearing of Nylon clothing while fueling the aircraft.

"Anyone remember the aircraft GROUNDING cables at air terminals?"

What do you mean remember, they still use them. Whenever an aircraft is being fueled they connect an earthing cable to the aircraft and pumping equipment prior to connecting the fuel hose to the aircraft.

"In the UK the locking type petrol nozzles were banned so you have to hold the pump trigger all the time that you are filling the car."

It's the same in Australia, if you let go of the handle the fuel stops flowing.

"Would it not make sense for the pump manufacturers to ground the nozzle so that the operator discharges any static as soon as they pick it up?"

As far as I know the pump nozzles are actually earthed. The problem can however be caused by a static build up on the car itself and as you move the nozzle towards the filling point you get a discharge from the car to the nozzle that can ignite the fumes from the tank and start a fire. For a while service stations had earthing straps that were basically wires that stuck up from the ground and contacted the under side of the car so that any static would be discharged as the car drew up to the pump. This however seems to have been abandoned now and I don't know what if anything is done now to ensure there is no static charge on the car prior to it being fueled. Even though mobile phones are known not to cause discharges that can start a fire every service station in Australia has warning signs stating the opposite. It's a real worry when the people that are making the rules are so out of touch with reality, it's probably the same inept bureaucrats that decided that grounding straps were no longer necessary.

"Anyone remember the aircraft GROUNDING cables at air terminals?"

If you ever see a helicopter landing on a ship, a member of the crew uses a long pole to discharge the static before it touches down.

"Even though mobile phones are known not to cause discharges....."

I was told once that the reason for the signs was to stop the phone signal interfering with the equipment metering the fuel.

The great thing about living in America is that if you do happen to do something really really stupid, and it blows up in your face, you can bet that someone got it on video:

http://www.pei.org/static/

Watch the video. Try not to laugh.

LOL, how could you not laugh hahaha... That's just hilarious. Don't they actually say not to take the nozzle out in the event that happens? I was pretty amazed there wasn't more fire! That's great, thanks for pointing that out. I wonder if there is any correlation between being blond, female, bad driving, and catching on fire

-Nick

I think the lack of an air supply keeps the car's fuel tank from exploding - she should have closed the fuel door, though, I think.

With that little bit of flame still burning on the nozzle, she could have made a nice little flame thrower.

Good thing she didn't have a big boufant hairdo held up with a lot of flammable hair spray.

For my own curiosity this past weekend I observed customers at a partucularly busy filling station. 3 were men and 3 were women. None of the men climbed back into their vehicles while fueling, but two on the women did. One woman was constantly in and out while talking on a cell phone. I observed the location of the fire extinguishers and was ready to come to assistance if needed.