safety concerns volatile chemicals

Hi All,

I have an industrial customer that wants to put
wireless into his factory floor. There are industrial
chemicals involved -- basically fixings to make spray
paint. Obviously, no smoking is allowed.

Is there ANY fire hazard involved with wireless
and the accidental ignition of volatile chemical?
(Bozos who talk on there cell phone while pumping
gasoline comes to mind.)

Many thanks,
--Tony

On Fri, 29 Jul 2005 14:01:04 -0700, Tony <(E-Mail Removed)> wrote:

> I have an industrial customer that wants to put
>wireless into his factory floor. There are industrial
>chemicals involved -- basically fixings to make spray
>paint. Obviously, no smoking is allowed.
>
> Is there ANY fire hazard involved with wireless
>and the accidental ignition of volatile chemical?
>(Bozos who talk on there cell phone while pumping
>gasoline comes to mind.)

Yeah, sorta. There's zero danger from the 50 milliwatts of RF
igniting anything. That's not enough to generate a spark. I can't
recall the name of the physics law that determines the energy
necessary to create a visible spark. However, it's substantially more
than what can be generated by a cell phone or wireless device.

However, the real danger in igniting volatiles and chemical fumes is
from power connectors, AC outlets, and battery chargers. All of these
will easily create a spark. Same with flashlight switches or any open
power switch. If the factory requires intrinsically safe electrical
devices and equipment, you will buy something that qualifies. In
general, mummifying the wireless device in an explosion proof
container is sufficient. This might be worth reading:
| http://www.process-heating.com/CDA/A...105469,00.html
If the factory does NOT require intrinsically safe equipment, then
just make an effort to reduce sparking and be done with it. The RF
won't do anything.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# http://802.11junk.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS

Generally electrical items must be certified safe in such environments. This
usually means that switches etc must be completely gas tight so that there
is no possibility of and arc or spark possibly igniting the environment.

As a guideline, find out if possibly portable two way radios are permitted
or used on the factory floor. If not, then consider an AP or other
electronic equipment in the same category. Process equipment will, or at
least should be certified in that environment.

Whichever way, ensure you have a written clearance accepting all liability
from the company that is legally sound, i.e. complies with any relevant
legislation regarding that workplace, before you attempt to supply or
install such equipment otherwise you could be in a sticky legal situation
should anything untoward happen, even if it is not specifically caused by
that equipment.

Incidentally, many gas stations now have signs stating that mobile phones
must be turned off completely before entering the filling areas.

Peter

"Tony" <(E-Mail Removed)> wrote in message
news:dce5g6$a5e$(E-Mail Removed)...
> Hi All,
>
> I have an industrial customer that wants to put
> wireless into his factory floor. There are industrial
> chemicals involved -- basically fixings to make spray
> paint. Obviously, no smoking is allowed.
>
> Is there ANY fire hazard involved with wireless
> and the accidental ignition of volatile chemical?
> (Bozos who talk on there cell phone while pumping
> gasoline comes to mind.)
>
> Many thanks,
> --Tony

Thank you. They do use two way radios. I will find out
if they were specially certified. Also, where the real
ignition danger is, they won't let but a select few people
through the special doors. And they have a real expensive
halon system to instantly extinguish anything. No
electronics at all are allowed through that door. I
will also make sure I am protected too.

--Tony


Pierre wrote:
> Generally electrical items must be certified safe in such environments. This
> usually means that switches etc must be completely gas tight so that there
> is no possibility of and arc or spark possibly igniting the environment.
>
> As a guideline, find out if possibly portable two way radios are permitted
> or used on the factory floor. If not, then consider an AP or other
> electronic equipment in the same category. Process equipment will, or at
> least should be certified in that environment.
>
> Whichever way, ensure you have a written clearance accepting all liability
> from the company that is legally sound, i.e. complies with any relevant
> legislation regarding that workplace, before you attempt to supply or
> install such equipment otherwise you could be in a sticky legal situation
> should anything untoward happen, even if it is not specifically caused by
> that equipment.
>
> Incidentally, many gas stations now have signs stating that mobile phones
> must be turned off completely before entering the filling areas.
>
> Peter
>
> "Tony" <(E-Mail Removed)> wrote in message
> news:dce5g6$a5e$(E-Mail Removed)...
>
>>Hi All,
>>
>> I have an industrial customer that wants to put
>>wireless into his factory floor. There are industrial
>>chemicals involved -- basically fixings to make spray
>>paint. Obviously, no smoking is allowed.
>>
>> Is there ANY fire hazard involved with wireless
>>and the accidental ignition of volatile chemical?
>>(Bozos who talk on there cell phone while pumping
>>gasoline comes to mind.)
>>
>>Many thanks,
>>--Tony
>
>
>

Jeff Liebermann wrote:
> On Fri, 29 Jul 2005 14:01:04 -0700, Tony <(E-Mail Removed)> wrote:
>
>
>> I have an industrial customer that wants to put
>>wireless into his factory floor. There are industrial
>>chemicals involved -- basically fixings to make spray
>>paint. Obviously, no smoking is allowed.
>>
>> Is there ANY fire hazard involved with wireless
>>and the accidental ignition of volatile chemical?
>>(Bozos who talk on there cell phone while pumping
>>gasoline comes to mind.)
>
>
> Yeah, sorta. There's zero danger from the 50 milliwatts of RF
> igniting anything. That's not enough to generate a spark. I can't
> recall the name of the physics law that determines the energy
> necessary to create a visible spark. However, it's substantially more
> than what can be generated by a cell phone or wireless device.
>
> However, the real danger in igniting volatiles and chemical fumes is
> from power connectors, AC outlets, and battery chargers. All of these
> will easily create a spark. Same with flashlight switches or any open
> power switch. If the factory requires intrinsically safe electrical
> devices and equipment, you will buy something that qualifies. In
> general, mummifying the wireless device in an explosion proof
> container is sufficient. This might be worth reading:
> | http://www.process-heating.com/CDA/A...105469,00.html
> If the factory does NOT require intrinsically safe equipment, then
> just make an effort to reduce sparking and be done with it. The RF
> won't do anything.
>
>

Thank you! They have a lot of electrical equipment on the
production line. Hmmmm. I wonder if it is certified or
there if there is no danger.

I have gotten RF burns on my fingers before (don't ask!),
but that was 30 watts.

--Tony

On Fri, 29 Jul 2005 20:44:15 -0700, Tony <(E-Mail Removed)> wrote:

>Thank you! They have a lot of electrical equipment on the
>production line. Hmmmm. I wonder if it is certified or
>there if there is no danger.

It can be certified as intrinsically safe with solid state switches
and non-sparking metals. I did such a conversion in about 1975 at
chemical plant.

I found the physics principle I mentioned. Check Google for "Paschen
Curve" or "Paschen's Law" which define what is necessary to create a
spark. Note that it's horribly non-linear below about 500 volts.

>I have gotten RF burns on my fingers before (don't ask!),
>but that was 30 watts.

Same here. I used to design marine radios for Intech Inc. I was
doing battle with an antenna tuner for 1.6-30Mhz. The test radio ran
150 watts PEP and 15 watts CW for tuning. At the 1.6Mhz, it was
possible to generated about 2000 volts at the top of one of the tuning
coils. Man, did that hurt.

Incidentally, one of my dumber fun projects was trying to build a
"modern" low power (QRP) miniature spark gap transmitter. The problem
was that Paschen's Law showed that the spark would not jump with the
12 volts I had to work with. I even tried to partially ionize the air
with some radioactive Thorium. Total failure. Oh well.

Again, incidentally, there are about 35 gasoline station fires each
year started from some type of spark. None of them are caused by cell
phones or radios. The most common culprit are relays, switches, and
starter motors. I have yet to see one start with a cell phone. I
once offered a friend $50 if he could ignite any flammable mixture
using RF from an unmodified cell phone. It's been about 10 years and
he still hasn't collected.

Where the original safety issue came from was from mobile radios that
used dynamotors or vibrator type power supplies. In the 1960's, these
huge radios (Motorola 5V, 40V, 80D etc) were mounted in the trunk,
above the gas tank. If the gas tank filled full of gas fumes during
filling, talking on the radio would generate a HUGE spark, that would
set off an explosion in the confined space of the trunk. This
happened to me in my 1960 Ford Falcon, which resulted in the back seat
getting shredded and sprayed all over the interior. Other friends and
customers had more spectacular explosions.

With the invention of solid-state radios, the elimination of open
frame relays for T/R switching, and the elimination of vented gas
tanks, the problem of exploding car trunks was almost completely
eliminated. However, the paranoia surrounding the issue 50 years
later, is still with us today. Sigh.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# http://802.11junk.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS

> (Bozos who talk on there cell phone while pumping
> gasoline comes to mind.)

Can you find a single reference to demonstrate where this has happened?

On Sat, 30 Jul 2005 11:07:52 GMT, David Taylor <(E-Mail Removed)>
wrote:

>> (Bozos who talk on there cell phone while pumping
>> gasoline comes to mind.)

>Can you find a single reference to demonstrate where this has happened?

Would you settle for exploding cell phone batteries?
http://www.wirelessconsumers.org/sit...YJ3OOF&b=14007
You never know when someone's cell phone might burst into flames,
ignite the gasoline vapors, and precipitate a litigatory and insurance
calamity. I suspect the odds are similar to those of getting hit by a
falling airplane, but why take chances?


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

> Would you settle for exploding cell phone batteries?
> http://www.wirelessconsumers.org/sit...YJ3OOF&b=14007
> You never know when someone's cell phone might burst into flames,
> ignite the gasoline vapors, and precipitate a litigatory and insurance
> calamity. I suspect the odds are similar to those of getting hit by a
> falling airplane, but why take chances?

Bzzz, close but not quite. Your earlier post summed it up. Any
suitable power source can cause a spark.

David.

On Sat, 30 Jul 2005 18:29:57 GMT, David Taylor <(E-Mail Removed)>
wrote:

>> Would you settle for exploding cell phone batteries?
>> http://www.wirelessconsumers.org/sit...YJ3OOF&b=14007
>> You never know when someone's cell phone might burst into flames,
>> ignite the gasoline vapors, and precipitate a litigatory and insurance
>> calamity. I suspect the odds are similar to those of getting hit by a
>> falling airplane, but why take chances?

>Bzzz, close but not quite. Your earlier post summed it up. Any
>suitable power source can cause a spark.
>David.

Y'er no fun. I guess the cell phone vibrator motor brushes could
generate enough of a spark to ignite the fumes and start a fire.

Once upon a time, before skool safety regulations were discovered, our
high skool brought in a fireman who demonstrated how critical the fuel
air mixture was to obtain a proper explosion. Just about any
concentration would burn, but you had to have about a 13:1 mixture in
order to get a real explosion. That was fun (and noisy).

Judging by the number of electrical fire related automobile recalls,
the most unsafe thing in the gas station is the vehicle.


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