Fuel level senders

F

Franc Zabkar

Guest
Could someone please explain why rheostat type fuel level senders as
used in automotive petrol tanks are considered safe? Intuition would
suggest that an intermitent contact could pose an ignition problem,
especially when the tank is full of vapour.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
One day Franc Zabkar got dressed and committed to text

Could someone please explain why rheostat type fuel level senders as
used in automotive petrol tanks are considered safe? Intuition would
suggest that an intermitent contact could pose an ignition problem,
especially when the tank is full of vapour.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Click to expand...
I imagine the current levels would preclude any arcing. Certainly they have
stood the test of time Franc :)

--
Regards ..... Rheilly Phoull
 
In article <6ado81l3tfrucu1jp6tcrsset5aorunbru@4ax.com>,
Franc Zabkar <fzabkar@optussnet.com.au> wrote:
Could someone please explain why rheostat type fuel level senders
as used in automotive petrol tanks are considered safe? Intuition
would suggest that an intermitent contact could pose an ignition
problem, especially when the tank is full of vapour.
Click to expand...
Ignition also needs the correct proportion of oxygen,
and (afaik) there is never enough oxygen in there.

--
Tony Williams.
 
bill.sloman@ieee.org wrote:
That is, the fuel concentration is above the Upper Explosive Limit
Click to expand...
Right, and the limits are pretty narrow as well. I remember playing
with a cork gun, a piece of steel tube with a spark plug at one end
and a cork at the other. Three drops of petrol popped the cork 20m
high. Two or four drops did nothing.

Jeroen Belleman
 
On Thu, 19 May 2005 14:15:05 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

bill.sloman@ieee.org wrote:
[...]
That is, the fuel concentration is above the Upper Explosive Limit


Right, and the limits are pretty narrow as well. I remember playing
with a cork gun, a piece of steel tube with a spark plug at one end
and a cork at the other. Three drops of petrol popped the cork 20m
high. Two or four drops did nothing.

Jeroen Belleman
Click to expand...
Years ago, helping a friend respray a car, we had a steel dustbin that
gradually got filled up with old rags soaked in cellulose thinners. At
the end of the day we decided to burn the rags, so we lit them through
a small hole in the bottom of the bin.

We never found the dustbin lid, and I have no idea how high it went.

d

Pearce Consulting
http://www.pearce.uk.com
 
On Thu, 19 May 2005 12:54:25 GMT, donald@pearce.uk.com (Don Pearce)
wrote:

On Thu, 19 May 2005 14:15:05 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

bill.sloman@ieee.org wrote:
[...]
That is, the fuel concentration is above the Upper Explosive Limit


Right, and the limits are pretty narrow as well. I remember playing
with a cork gun, a piece of steel tube with a spark plug at one end
and a cork at the other. Three drops of petrol popped the cork 20m
high. Two or four drops did nothing.

Jeroen Belleman

Years ago, helping a friend respray a car, we had a steel dustbin that
gradually got filled up with old rags soaked in cellulose thinners. At
the end of the day we decided to burn the rags, so we lit them through
a small hole in the bottom of the bin.

We never found the dustbin lid, and I have no idea how high it went.

d
Click to expand...
I had a friend who tried to solder a leaky, assumed-empty car gas tank
with a propane torch. It came out sort of spherical.

John
 
bill.sloman@ieee.org wrote:

IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm
Click to expand...
This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).

Graham
 
John Larkin wrote:

On Thu, 19 May 2005 12:54:25 GMT, donald@pearce.uk.com (Don Pearce)
wrote:

On Thu, 19 May 2005 14:15:05 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

bill.sloman@ieee.org wrote:
[...]
That is, the fuel concentration is above the Upper Explosive Limit


Right, and the limits are pretty narrow as well. I remember playing
with a cork gun, a piece of steel tube with a spark plug at one end
and a cork at the other. Three drops of petrol popped the cork 20m
high. Two or four drops did nothing.

Jeroen Belleman

Years ago, helping a friend respray a car, we had a steel dustbin that
gradually got filled up with old rags soaked in cellulose thinners. At
the end of the day we decided to burn the rags, so we lit them through
a small hole in the bottom of the bin.

We never found the dustbin lid, and I have no idea how high it went.

d

I had a friend who tried to solder a leaky, assumed-empty car gas tank
with a propane torch. It came out sort of spherical.

John
Click to expand...
I see you use the past tense ' *had* a friend ' !

Graham
 
On Thu, 19 May 2005 13:09:24 -0700, "Paul Hovnanian P.E."
<Paul@Hovnanian.com> wrote:

Pooh Bear wrote:

bill.sloman@ieee.org wrote:

IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm

This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).

That was a surface to air missile.
Click to expand...
Paul! Paul! Paul! Paul!

Get real. Everyone in the industry knows the failure mechanism was in
the tank-to-tank pump.

Sheeesh!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Pooh Bear wrote:
bill.sloman@ieee.org wrote:

IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm

This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).
Click to expand...
That was a surface to air missile.

--
Paul Hovnanian mailto:paul@Hovnanian.com
------------------------------------------------------------------
In the beginning, there was nothing. And God said, "Let there be Light."
And there was still nothing, but you could see it.
 
In article <428CF274.46FB9E1C@Hovnanian.com>, Paul@Hovnanian.com
says...
Pooh Bear wrote:

bill.sloman@ieee.org wrote:

IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm

This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).

That was a surface to air missile.

Nonsense. The pilot wasn't wearing his tinfoil hat when he was hit
Click to expand...
with an Illudium PU36 Explosive Space Mudulator beam.

Remember, shiny side out!

--
Keith
 
On Thu, 19 May 2005 09:02:54 -0700, John Larkin wrote:

On Thu, 19 May 2005 12:54:25 GMT, donald@pearce.uk.com (Don Pearce)
wrote:

On Thu, 19 May 2005 14:15:05 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

bill.sloman@ieee.org wrote:
[...]
That is, the fuel concentration is above the Upper Explosive Limit


Right, and the limits are pretty narrow as well. I remember playing
with a cork gun, a piece of steel tube with a spark plug at one end
and a cork at the other. Three drops of petrol popped the cork 20m
high. Two or four drops did nothing.

Jeroen Belleman

Years ago, helping a friend respray a car, we had a steel dustbin that
gradually got filled up with old rags soaked in cellulose thinners. At
the end of the day we decided to burn the rags, so we lit them through
a small hole in the bottom of the bin.

We never found the dustbin lid, and I have no idea how high it went.

d

I had a friend who tried to solder a leaky, assumed-empty car gas tank
with a propane torch. It came out sort of spherical.
Click to expand...
I saw a guy at a car shop who had taken the gas tank off some car, and
poured the leftover gasoline into a 5-gallon bucket. Not very much
gasoline, there was about 1" - 2" of gasoline in the bottom of the bucket.
We were all smoking, (back in those days, almost everybody smoked) and I
said to the guy, "Hey, I've heard that a lit cigarette won't ignite
gasoline. Do you know if that's true?" He didn't say anything, just took
his cigarette and flicked it into the bucket. It went "SSst" as if it had
been flicked into water.

Cheers!
Rich
 
On 19 May 2005 02:08:52 -0700, bill.sloman@ieee.org put finger to
keyboard and composed:

IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm
Click to expand...
Thanks, that makes sense. I guess it is very difficult to achieve a
stoichiometric ratio inside the fuel tank.

I recall a friend who was a panel beater telling me that he used to
weld petrol tanks after filling them with fuel. His colleagues thought
he was mad, but he survived, only to die of prostate cancer many years
later.

------------
Bill Sloman, Nijmegen
Click to expand...

- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
On Thu, 19 May 2005 16:13:00 +0800, "Rheilly Phoull"
<Rheilly@bigpong.com> put finger to keyboard and composed:

One day Franc Zabkar got dressed and committed to text

Could someone please explain why rheostat type fuel level senders as
used in automotive petrol tanks are considered safe? Intuition would
suggest that an intermitent contact could pose an ignition problem,
especially when the tank is full of vapour.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

I imagine the current levels would preclude any arcing. Certainly they have
stood the test of time Franc :)
Click to expand...
I've never really doubted that petrol tanks are safe. I just wanted to
know why. As for low current being the reason, I'd expect that the
tank would need to tolerate the situation where the full supply
voltage was applied to the sender when it was at the low end of its
resistance range. I imagine this could occur as the result of a wiring
error during a dashboard repair, say, or if the fuel gauge failed in
some peculiar way.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
Paul Hovnanian P.E. wrote:

Pooh Bear wrote:

bill.sloman@ieee.org wrote:


IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm

This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).


That was a surface to air missile.
Click to expand...
I heard it was somebody smoking in the bathroom.

--
Luhan Monat: luhanis(at)yahoo(dot)com
http://members.cox.net/berniekm
"Any sufficiently advanced magick is
indistinguishable from technology."
 
On Thu, 19 May 2005 15:22:59 -0700, Luhan Monat <x@y.z> wrote:

Paul Hovnanian P.E. wrote:

Pooh Bear wrote:

bill.sloman@ieee.org wrote:


IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm

This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).


That was a surface to air missile.


I heard it was somebody smoking in the bathroom.
Click to expand...
Yep, Blew his ass off ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
John Larkin wrote:
I had a friend who tried to solder a leaky, assumed-empty car gas tank
with a propane torch. It came out sort of spherical.
Click to expand...
It's not uncommon to feed a pipe from the exhaust of a running car
into a fuel tank so you can weld it safely. It's easier to remove
the oxygen than to remove the residual fuel...
 
Jim Thompson wrote:
On Thu, 19 May 2005 13:09:24 -0700, "Paul Hovnanian P.E."
Paul@Hovnanian.com> wrote:

Pooh Bear wrote:

bill.sloman@ieee.org wrote:

IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm

This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).

That was a surface to air missile.

Paul! Paul! Paul! Paul!

Get real. Everyone in the industry knows the failure mechanism was in
the tank-to-tank pump.
Click to expand...
Wrong. From http://www.ntsb.gov/Publictn/2000/aar0003.htm

"The National Transportation Safety Board determines that the probable
cause of the TWA flight 800 accident was an explosion of the center wing
fuel tank (CWT), resulting from ignition of the flammable fuel/air
mixture in the tank. The source of ignition energy for the explosion
could not be determined with certainty, but, of the sources evaluated by
the investigation, the most likely was a short circuit outside of the
CWT that allowed excessive voltage to enter it through electrical wiring
associated with the fuel quantity indication system."

They don't really know what caused the CWT to blow, but they are pinning
the problem on the FQIS. So much for the theory that fuel level senders
are safe. Cars should be blowing up right and left on the freeway from
the senders, not to mention immersed electric fuel pumps.

What I wonder about is: Following the accident, the FAA attempted to
identify and interview the crew of every aircraft operating in the area.
One aircraft, shown on radar flying in circles nearby, was never found
and no crew ever came forward. There is one type of aircraft that
exhibits this behavior. A target drone.

--
Paul Hovnanian mailto:paul@Hovnanian.com
------------------------------------------------------------------
"The beauty of a chainsaw is that you don't have to start it. Just
show up with it." - Joe Walsh, on checking in to hotels.
 
On Thu, 19 May 2005 17:22:00 +1000, Franc Zabkar wrote:

Could someone please explain why rheostat type fuel level senders as
used in automotive petrol tanks are considered safe? Intuition would
suggest that an intermitent contact could pose an ignition problem,
especially when the tank is full of vapour.
Click to expand...
They (and the electric pump) are usually submursed under the fuel. It's
never a good idea to run the tank dry because the fuel also lubricates
the pump bearings.

--
Keith
 
On Thu, 19 May 2005 19:35:38 -0700, Paul Hovnanian P.E. wrote:

Jim Thompson wrote:

On Thu, 19 May 2005 13:09:24 -0700, "Paul Hovnanian P.E."
Paul@Hovnanian.com> wrote:

Pooh Bear wrote:

bill.sloman@ieee.org wrote:

IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty
petrol tank, because the saturation concentration of inflammable gases
above liquid petrol/gasoline at room temperature is too high to sustain
combustion (the fuel-air mix is too rich).

That is, the fuel concentration is above the Upper Explosive Limit

http://www.imakenews.com/aristatek/e_article000126616.cfm

This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix
that is ).

That was a surface to air missile.

Paul! Paul! Paul! Paul!

Get real. Everyone in the industry knows the failure mechanism was in
the tank-to-tank pump.

Wrong. From http://www.ntsb.gov/Publictn/2000/aar0003.htm

"The National Transportation Safety Board determines that the probable
cause of the TWA flight 800 accident was an explosion of the center wing
fuel tank (CWT), resulting from ignition of the flammable fuel/air
mixture in the tank. The source of ignition energy for the explosion
could not be determined with certainty, but, of the sources evaluated by
the investigation, the most likely was a short circuit outside of the
CWT that allowed excessive voltage to enter it through electrical wiring
associated with the fuel quantity indication system."

They don't really know what caused the CWT to blow, but they are pinning
the problem on the FQIS. So much for the theory that fuel level senders
are safe. Cars should be blowing up right and left on the freeway from
the senders, not to mention immersed electric fuel pumps.

What I wonder about is: Following the accident, the FAA attempted to
identify and interview the crew of every aircraft operating in the area.
One aircraft, shown on radar flying in circles nearby, was never found
and no crew ever came forward. There is one type of aircraft that
exhibits this behavior. A target drone.
Click to expand...
Shiny side out! How many times do you need to be told. Sheesh!

--
Keith
 
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