Now I'm no RF design engineer (Radio Frequency), but having worked over the last few years with companies producing products from simple ISM band radios to military grade microwave communications and sophisticated jamming equipment, I like to think I know a little about RF.
This brings me to my story of when I pulled into the petrol station yesterday whilst talking on my mobile phone. My friend who was driving jumped out and began to fill up, whilst I continued my conversation. A few moments later an irate voice came over the loudspeaker telling me to stop using my mobile phone as it is dangerous to do so on the forecourt.
A bit of an overreaction I thought? Firstly I was sealed inside the car, and secondly, to my knowledge, there is absolutely no evidence that transceiver devices such as mobile phones can cause a explosion by igniting fuel vapour?
However, there are signs posted all over the forecourt about not using your mobile phone? There appears to be a few theories around, including RF being the cause or the potential sparking from the battery contacts that can potentially ignite fuel vapour. The average mobile phone kicks out about 1 to 2 watts at peak power, so generally it's only at its maximum output when its furthest from a base station. 1 to 2 watts is barely enough heat to cause an explosion, especially when considering it takes about 1 minute for a 1000 watt Microwave oven to boil a cup of water, and that’s concentrated energy shielded in a box. Interestingly enough, in the UK, you may well have noticed that many Petrol Stations have cellular masts on their roofs, so a slight contradiction here I think!
In fact the most likely way to cause an explosion is from static electricity. The best way to clean yourself of static electricity is to ground yourself by touching the body work of your car as you step out onto the forecourt. By doing this, when you start to fill up, you should then be discharged of any static leaving your fingers that could ignite fuel vapour.
If you have any views or comments on this subject, please feel free to comment.
Below is a video from one of my favourite TV's shows that you may enjoy on this subject.
I am an engineer who has worked in flame and explosion prevention. I have also worked in the research department of a major oil company and did an investigation into fires and explosions on garage forecourts in Europe.
Mobile phones are not ‘intrinsically safe’, that is, they are not designed to be used in explosive atmosphere. Having said that, the RF power produced is relatively low and would be very unlikely to produce and explosion. Two people however were killed and one seriously injured a few years ago at a gas bottling plant in Europe when a mobile phone fell from one of the workers pockets. The phone was switched off at the time, as regulations stated they should be, but as the phone hit the ground the battery was dislodged and the spark ignited the gas.
I have also seen video footage of a fuel tanker driver being blown from the top of his vehicle when attempting to turn off his mobile phone when it rang. Ironically, if he had ignored it he probably would have been ok. Again, very unlikely to be the RF energy, but a spark from the non-intrinsically designed switch contacts.
The majority of fires on forecourts are caused by static and there are many reasons how and why this can occur. By far biggest reason though is because of ‘vapour recovery’. A number of filling stations in Britain have this but it is more common in mainland Europe. It is a system brought in to reduce the environmental impact of fuel vapour lost into the atmosphere whilst refuelling. A vacuum is used to suck fuel vapour from the filler back through a concentric fuel hose into the supply tank. Unfortunately this is not perfect and some fuel vapour is still present around the filler nozzle. With a high concentration of fuel vapour to air, the vapour is difficult to ignite, similarly at the other extreme, a small proportion of fuel to a lot or air is also relatively safe. The problem with Vapour Recovery means that the ratio of fuel vapour to air is now smack in the middle of the ‘explosion band’ and it is very easy to ignite!
In answer to the comments about using a phone inside a sealed car or on the pavement outside, this is ‘over the top’ and in the past I have been apprehended for using one inside the forecourt shop. Although tempted, instead of giving them a lecture about the actual hazards, I have just apologised and accepted that they are doing the job that they have been asked to do.
No matter though how low the risk is, I recommend taking the phone from your pocket and leaving it in the car! With the windows closed.
Some years ago I read article of how this rumor started. I tried to find the article but was unable to do so. But what I read was how a reporter wrote up the story that a man pumping gas while using his cell when the fire started. But the real truth was the man was in the store talking on his cell when he looked out and saw his car on fire. There was a real fire and the man was talking on his cellphone but it was still misinformation on the news organization's part.
More than likely the fire was started by something like a static charge from something else. I personally went on a trip with some friends, one who received a nasty shock every time he tried to enter the car. Since he was the only one receiving these shocks I theorize that the source of his shocks were the shoes he was wearing. I told him to hold his key out toward the door and a spark jumped between the key and the body of the car. This prevented him from receiving the painful shock. But I could see how this could also ignite a gas fire.
When I was doing some work for a major chemical plant I observed their rule that all vehicles were to be grounded with a grounding wire with a clip before fueling. This was to prevent static charged sparks from igniting the fumes.
As for the warning labels, it don't take much to understand why they are there. In today's atmosphere of “quick to sue for damages”, many companies are following their legal counsel's advice of “better safe than sorry”.
As someone has mentioned below, there are products designed to be 'intrinsically safe' for these environments, but the risk from a relatively low powered transmitter is small to negligible in my view. The products I've seen have been higher-powered hand-held transceivers, and whilst there are internal design features (silicone potting for example) to eliminate risk, the RF antenna is still present, and presumably they are designed *for use* within these environments, implying that the RF itself is not the concern, and that as you suggest, electrostatic discharge or sparking is the primary concern.
What really makes a mockery of the signs though is that your mobile phone is trasmitting *even when you're not in a call*.
It's intermittently contacting cell sites and in the case of a modern smartphone, with always-on data connections, could be transmitting even when in your pocket.
For this reason the signs are pointless, unless they insist upon you switching off your mobile whilst at the pump :)
I thought I heard that mobile phones years ago interfered with the older petrol pumps hence the reason they were banned on the forecourt. There seems far more risk of your body electrostatically discharging and igniting fuel vapour but you don't see signs telling you to earth yourself before fuelling. Seems stupid to me.
No real-world evidence exists to support these claims. Although Internet rumorshave circulated since 1999 to the effect that cell phone use near gas pumps can cause fires or explosions by igniting gasoline vapors (prompting many service stations to post warnings on their pumps), not a single case has ever been documented.
According to Shell Oil, allegedly the source of the information, the email is a complete hoax and did not originate from the company. "We're not aware that there has ever been an incident where this has happened," a Shell representative told Reuters in February 2003. A mobile phone industry spokesperson labeled it an "urban legend."
The earliest rumors connecting wireless phones with refueling fires have been traced back to a 1999 China Post article alleging that an Indonesian driver was badly burned when "a spark from the static electricity in the mobile [phone] ignited the petrol vapor," blowing up his car. Though never independently confirmed, the tale won credulity among cautious petroleum industry executives, in part because some cellular phone manuals shipped during the 1990s contained warnings against using the products anywhere gasoline vapors might be present. But the danger was, and is, purely theoretical. An investigation completed in 2001 by the Center for the Study of Wireless Electromagnetic Compatibility at the University of Oklahoma found "virtually no evidence to suggest that cell phones pose a hazard at gas stations."
Adding to the confusion, more recent research strongly indicates that static electricity from sources other than cell phones can ignite gasoline vapors at the pump and cause vehicular fires, of which there have been many documented cases. Unfortunately, the rumor mill being what it is, this important information has been obfuscated by sketchy email alerts which persist in claiming that some of the fires were caused by "sparks" from mobile phones.
I too am not an RF engineer, but I have worked on intrinsic safety with the NCB and on munitions detonation, and the energy levels required to create a spark large enough to ignite petrol vapour is very small indeed, and is well within the scope of a mobile phono transmitter and a resonant piece of metal in the right place. I also know the safety rule that says if you cannot PROVE that it is safe, then assume that it isn't.
I agree that biggest spark generator is electrostatic, and a second one is the arcing at motor contacts, so I make sure that I am discharged against the car and lock the doors BEFORE I unscrew the fuel cap. Once the vapour leaves the tank it disperses very quickly so that risk is greatly reduced.
I believe in the Thomas Moore attitude that if you can't hide behind the law (or rules) then where can you hide? So if there are rules displayed then obey them and others can have no cause for complaint.
Richard Hammond tested this on Brainiac a while ago.
They found that they couldn't get an explosion when they called a number of mobile phones inside a caravan full of petrol but as soon as they generated a static charge on their body and were wired to the caravan, it exploded.
Perhaps it is simply that pumping litres per minute of highly falmable liquid using a flexible hose loosely plugged into a filler pipe is regarded as a task requiring 100% attention? OK you were not actually in charge of the hose when you were shouted at, but rules is rules and you cannot always expect a garage attendent on minimum wages to excercise discretion based on a full scientific risk assessment!
Since when do we blindly follow the rules without any question as to why these are there?
In case of the mobile phones versus the fuel fumes, I think somebody invented this rules because of hearsay, not any evidence that I could find.
I was harrassed very aggressively by an overly eager garage attendant while on an important phone call, not even while tanking but just standing on the pavement outside the station. When I asked him what was the basis of this rule he was defending so offensively, he could not tell me but just rules is rules. Pathetic.
OxfordRoger
I am an engineer who has worked in flame and explosion prevention. I have also worked in the research department of a major oil company and did an investigation into fires and explosions on garage forecourts in Europe.
Mobile phones are not ‘intrinsically safe’, that is, they are not designed to be used in explosive atmosphere. Having said that, the RF power produced is relatively low and would be very unlikely to produce and explosion. Two people however were killed and one seriously injured a few years ago at a gas bottling plant in Europe when a mobile phone fell from one of the workers pockets. The phone was switched off at the time, as regulations stated they should be, but as the phone hit the ground the battery was dislodged and the spark ignited the gas.
I have also seen video footage of a fuel tanker driver being blown from the top of his vehicle when attempting to turn off his mobile phone when it rang. Ironically, if he had ignored it he probably would have been ok. Again, very unlikely to be the RF energy, but a spark from the non-intrinsically designed switch contacts.
The majority of fires on forecourts are caused by static and there are many reasons how and why this can occur. By far biggest reason though is because of ‘vapour recovery’. A number of filling stations in Britain have this but it is more common in mainland Europe. It is a system brought in to reduce the environmental impact of fuel vapour lost into the atmosphere whilst refuelling. A vacuum is used to suck fuel vapour from the filler back through a concentric fuel hose into the supply tank. Unfortunately this is not perfect and some fuel vapour is still present around the filler nozzle. With a high concentration of fuel vapour to air, the vapour is difficult to ignite, similarly at the other extreme, a small proportion of fuel to a lot or air is also relatively safe. The problem with Vapour Recovery means that the ratio of fuel vapour to air is now smack in the middle of the ‘explosion band’ and it is very easy to ignite!
In answer to the comments about using a phone inside a sealed car or on the pavement outside, this is ‘over the top’ and in the past I have been apprehended for using one inside the forecourt shop. Although tempted, instead of giving them a lecture about the actual hazards, I have just apologised and accepted that they are doing the job that they have been asked to do.
No matter though how low the risk is, I recommend taking the phone from your pocket and leaving it in the car! With the windows closed.
Ongytenes
Some years ago I read article of how this rumor started. I tried to find the article but was unable to do so. But what I read was how a reporter wrote up the story that a man pumping gas while using his cell when the fire started. But the real truth was the man was in the store talking on his cell when he looked out and saw his car on fire. There was a real fire and the man was talking on his cellphone but it was still misinformation on the news organization's part.
More than likely the fire was started by something like a static charge from something else. I personally went on a trip with some friends, one who received a nasty shock every time he tried to enter the car. Since he was the only one receiving these shocks I theorize that the source of his shocks were the shoes he was wearing. I told him to hold his key out toward the door and a spark jumped between the key and the body of the car. This prevented him from receiving the painful shock. But I could see how this could also ignite a gas fire.
When I was doing some work for a major chemical plant I observed their rule that all vehicles were to be grounded with a grounding wire with a clip before fueling. This was to prevent static charged sparks from igniting the fumes.
As for the warning labels, it don't take much to understand why they are there. In today's atmosphere of “quick to sue for damages”, many companies are following their legal counsel's advice of “better safe than sorry”.
alweekes
As someone has mentioned below, there are products designed to be 'intrinsically safe' for these environments, but the risk from a relatively low powered transmitter is small to negligible in my view. The products I've seen have been higher-powered hand-held transceivers, and whilst there are internal design features (silicone potting for example) to eliminate risk, the RF antenna is still present, and presumably they are designed *for use* within these environments, implying that the RF itself is not the concern, and that as you suggest, electrostatic discharge or sparking is the primary concern.
What really makes a mockery of the signs though is that your mobile phone is trasmitting *even when you're not in a call*.
It's intermittently contacting cell sites and in the case of a modern smartphone, with always-on data connections, could be transmitting even when in your pocket.
For this reason the signs are pointless, unless they insist upon you switching off your mobile whilst at the pump :)
murrayn
I thought I heard that mobile phones years ago interfered with the older petrol pumps hence the reason they were banned on the forecourt. There seems far more risk of your body electrostatically discharging and igniting fuel vapour but you don't see signs telling you to earth yourself before fuelling. Seems stupid to me.
tofwerk
Aircrafts usually gets groundet for fueling. Now I know why :-)
colin_b
Interesting here are some links to Kent University research on the subject and the Australian Transport Safety Bureau
Both seem to be of the opinion that the concern is overrated.
The ATSB is actually looking at static and your mobile phone exploding rather than the petrol station.
http://www.esdjournal.com/static/Static_Fires.pdf ATSB
http://littleurl.info/yav Kent University research paper.
dtemcar
From Urban Legends:
No real-world evidence exists to support these claims. Although Internet rumorshave circulated since 1999 to the effect that cell phone use near gas pumps can cause fires or explosions by igniting gasoline vapors (prompting many service stations to post warnings on their pumps), not a single case has ever been documented.
According to Shell Oil, allegedly the source of the information, the email is a complete hoax and did not originate from the company. "We're not aware that there has ever been an incident where this has happened," a Shell representative told Reuters in February 2003. A mobile phone industry spokesperson labeled it an "urban legend."
The earliest rumors connecting wireless phones with refueling fires have been traced back to a 1999 China Post article alleging that an Indonesian driver was badly burned when "a spark from the static electricity in the mobile [phone] ignited the petrol vapor," blowing up his car. Though never independently confirmed, the tale won credulity among cautious petroleum industry executives, in part because some cellular phone manuals shipped during the 1990s contained warnings against using the products anywhere gasoline vapors might be present. But the danger was, and is, purely theoretical. An investigation completed in 2001 by the Center for the Study of Wireless Electromagnetic Compatibility at the University of Oklahoma found "virtually no evidence to suggest that cell phones pose a hazard at gas stations."
Adding to the confusion, more recent research strongly indicates that static electricity from sources other than cell phones can ignite gasoline vapors at the pump and cause vehicular fires, of which there have been many documented cases. Unfortunately, the rumor mill being what it is, this important information has been obfuscated by sketchy email alerts which persist in claiming that some of the fires were caused by "sparks" from mobile phones.
GANDALF
I too am not an RF engineer, but I have worked on intrinsic safety with the NCB and on munitions detonation, and the energy levels required to create a spark large enough to ignite petrol vapour is very small indeed, and is well within the scope of a mobile phono transmitter and a resonant piece of metal in the right place. I also know the safety rule that says if you cannot PROVE that it is safe, then assume that it isn't.
I agree that biggest spark generator is electrostatic, and a second one is the arcing at motor contacts, so I make sure that I am discharged against the car and lock the doors BEFORE I unscrew the fuel cap. Once the vapour leaves the tank it disperses very quickly so that risk is greatly reduced.
I believe in the Thomas Moore attitude that if you can't hide behind the law (or rules) then where can you hide? So if there are rules displayed then obey them and others can have no cause for complaint.
telesound
Richard Hammond tested this on Brainiac a while ago.
They found that they couldn't get an explosion when they called a number of mobile phones inside a caravan full of petrol but as soon as they generated a static charge on their body and were wired to the caravan, it exploded.
JohnHind
Perhaps it is simply that pumping litres per minute of highly falmable liquid using a flexible hose loosely plugged into a filler pipe is regarded as a task requiring 100% attention? OK you were not actually in charge of the hose when you were shouted at, but rules is rules and you cannot always expect a garage attendent on minimum wages to excercise discretion based on a full scientific risk assessment!
Flywheel
Silly rules are just that, silly.
Since when do we blindly follow the rules without any question as to why these are there?
In case of the mobile phones versus the fuel fumes, I think somebody invented this rules because of hearsay, not any evidence that I could find.
I was harrassed very aggressively by an overly eager garage attendant while on an important phone call, not even while tanking but just standing on the pavement outside the station. When I asked him what was the basis of this rule he was defending so offensively, he could not tell me but just rules is rules. Pathetic.
Show me the evidence.