Wireless around flammable liquids

We have a customer interested in installing access points in track
service bays etc. for their wireless diagnostics systems. (laptops
with wireless cards)

They've asked the question - is wireless safe round the fuel, oil etc?

Could the kit cause a static, sparks etc? I suppose, similar to what
we're told about switching off mobiles in petrol station forecourts -
although people do say this is an urban legend.

Does anyone know of any sites/docs that would be useful to quote to
reassure?

Access points we'd use would be Cisco Aironet 1231G, with DC Injectors
(located out of harms way, in comms cabinet).


Many thanks!

Sorry, sausage fingers stike again!

*track= TRUCK

"Emlynfluff" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
>
> We have a customer interested in installing access points in track
> service bays etc. for their wireless diagnostics systems. (laptops
> with wireless cards)
>
> They've asked the question - is wireless safe round the fuel, oil etc?
>
> Could the kit cause a static, sparks etc? I suppose, similar to what
> we're told about switching off mobiles in petrol station forecourts -
> although people do say this is an urban legend.
>
> Does anyone know of any sites/docs that would be useful to quote to
> reassure?
>
> Access points we'd use would be Cisco Aironet 1231G, with DC Injectors
> (located out of harms way, in comms cabinet).
>
>
> Many thanks!

If you are talking about a normal Truck repair workshop then there would be
no problems, the RF on a wireless card is very low. If you are in a
refinary or tanker terminal for petrol or gas then the Petrolium
Regulations come into force and they are very strict.
The 'no wireless' on forecourts comes from the higher powered communication
transmitters which could put out a lot more power, and could theoretically
cause a spark . You can get special radios that are Intrinsically safe for
use in Volatile areas, mines, explosives, fuel and gas etc.
Mobile phones only put out miliwatts so should not be a problem. but I will
let you test that out first! ;~)

"Emlynfluff" <(E-Mail Removed)> wrote:
>They've asked the question - is wireless safe round the fuel, oil etc?

Unless there are legal requirement for intrinsically safe hardware, or
the owner has some reason to believe that there are explosive fumes
that'll build up, you shouldn't have a problem.

"Emlynfluff" <(E-Mail Removed)> hath wroth:

>We have a customer interested in installing access points in track
>service bays etc. for their wireless diagnostics systems. (laptops
>with wireless cards)
>
>They've asked the question - is wireless safe round the fuel, oil etc?

Yes. The wireless part is sufficiently low power that there will not
be a spark.

>Could the kit cause a static, sparks etc? I suppose, similar to what
>we're told about switching off mobiles in petrol station forecourts -
>although people do say this is an urban legend.

It's urban legend. In the bad olde daze of tube (valve) mobile
radios, the high voltage power supplies consisted of dynamotors (a
type of motor generator) and vibrator (relay switcher) type power
supplies. These generated real and visible sparks which could easily
set off a vapor explosion. In addition, the old tube radios were
mounted in the trunk of the vehicle, with no vapor seal from the gas
tank, which made the trunk into a perfect confined area. I had a
small explosion in the trunk of my 1960 Ford Falcon from exactly this
situation.

A bit later, the dynamotors and vibrators were replace by transistor
driven switchers, but the T/R relays were still wide open and
generated sparks. Eventually, the T/R relays were replaced by solid
state T/R switches and the RF switches by sealed reed relays. That
eliminated all obvious sources of sparking. However, tradition is
difficult to fight, so the warnings about turning off the radios
remain. "Better safe than understanding."

>Does anyone know of any sites/docs that would be useful to quote to
>reassure?

I couldn't find anything specific. Maybe later. Avoid anything about
"intrinsically safe" unless you're working inside a gasoline storage
tank. Sparking is described by Paschen's Law:
http://en.wikipedia.org/wiki/Paschen's_law
This is the minimum voltage and power required to generate an arc at a
specified gas pressure. At low powers and voltages, there's no real
danger.
http://home.earthlink.net/~jimlux/hv/paschen.htm

Duh... Found my own posting on the same topic.
http://www.wifi-forum.com/wf/showthread.php?t=53764

The real danger is the 48VDC PoE power supply generating sparks when
plugged and unplugged. This is a rather uncommon event and should not
be a consideration. In addition, the PoE specification has provisions
for not applying full power until after the requisite data handshake.
During the handshake, there's not enough power applied to generate a
spark. PoE will not deliver power into a short circuit. Not a
problem.

>Access points we'd use would be Cisco Aironet 1231G, with DC Injectors
>(located out of harms way, in comms cabinet).

Those are really nice access points.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <(E-Mail Removed)> wrote:
>"Emlynfluff" <(E-Mail Removed)> hath wroth:
>>we're told about switching off mobiles in petrol station forecourts -

>It's urban legend.

Many cellphones have vibrators in them, which are essentially electric
motors with brushes, and could create sparks.

[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]

In <(E-Mail Removed)> on Wed, 26 Apr 2006 18:23:54
-0400, William P.N. Smith <(E-Mail Removed)> wrote:

>Jeff Liebermann <(E-Mail Removed)> wrote:
>>"Emlynfluff" <(E-Mail Removed)> hath wroth:
>>>we're told about switching off mobiles in petrol station forecourts -
>
>>It's urban legend.
>
>Many cellphones have vibrators in them, which are essentially electric
>motors with brushes, and could create sparks.

You're sure they're not brushless? At least some are:
<http://www.electronicstalk.com/news/omr/omr195.html>
<http://www.globalsources.com/gsol/I/Vibration-motor/p/2000000003844/3000000157581/sm/1001669909.htm>

--
Best regards, SEE THE FAQ FOR ALT.INTERNET.WIRELESS AT
John Navas <http://en.wikibooks.org/wiki/FAQ_for_alt.internet.wireless>

William P.N. Smith wrote:

> Jeff Liebermann <(E-Mail Removed)> wrote:
>>"Emlynfluff" <(E-Mail Removed)> hath wroth:
>>>we're told about switching off mobiles in petrol station forecourts -
>
>>It's urban legend.
>
> Many cellphones have vibrators in them, which are essentially electric
> motors with brushes, and could create sparks.

It's still urban legend. There are any number of things in a car that could
create sparks - most cars have fans that run independent of the ignition
setting these days, I'd bet those have a better chance of creating a spark
at the gas pumps.
--
derek

William P.N. Smith <(E-Mail Removed)> hath wroth:

>Jeff Liebermann <(E-Mail Removed)> wrote:
>>"Emlynfluff" <(E-Mail Removed)> hath wroth:
>>>we're told about switching off mobiles in petrol station forecourts -
>
>>It's urban legend.

>Many cellphones have vibrators in them, which are essentially electric
>motors with brushes, and could create sparks.

True. However, the motors are fairly well enclosed. For example, the
mine safety people have been using vibrating pagers in mines for many
years to send text message warnings of fire, gas, etc. They use the
vibrators because of the high noise level in the mines.

http://www.pei.org/static/ (There is quite a bit here)

I vaguely recall it became an issue with pagers in the 1980's. There
was a demonstration with a gallon plastic pickle jar, a few drops of
gasoline, and a pager. The vibrator motor sparking allegedly caused
the gasoline vapor to explode. A friend of mine tried to dupllicate
the effect with several Motorola Bravo pagers, and never could get it
to do anything. He eventually fired off a spark inside the plastic
jar with a big inductor, which verified that the atmosphere was indeed
explosive. I have the videos of all this buried somewhere.

This should probably be tested by Myth Busters.
Oh, it already has been. The "Cell Phones and Gas Stations" episode.
http://www.mythbustersfanclub.com/ht...s_station.html
http://www.snopes.com/autos/hazards/gasvapor.asp
http://www.museumofhoaxes.com/hoax/w...comments/2604/

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

(E-Mail Removed) (Jeff Liebermann) wrote in
news:(E-Mail Removed):

> True. However, the motors are fairly well enclosed. For example, the
> mine safety people have been using vibrating pagers in mines for many
> years to send text message warnings of fire, gas, etc.

But I'd bet that the pagers (and other equipment) have been tested and
rated as "intrinsically safe".

See

http://www.commtechwireless.com/page...afe_pagers.php

and others.

--
Bert Hyman | St. Paul, MN | (E-Mail Removed)