In-the-tank fuel pumps cause death and destruction

Ken Weitzel wrote:
>
> Bill Putney wrote:
>
>> Ken Weitzel wrote:

>>> I do have one question though that I'd like to ask if
>>> I may? When I have a quarter tank of fuel left, what
>>> exactly occupies the remaining space?

>> If I see where you're going with this, the inside of the fuel pump
>> (where all the electrical commutation/sparking takes place) is 100%
>> full of liquid fuel under all conditions. Missing only one ingredient
>> for fire or explosion: air/oxygen. Comforting thought, eh?
>>
>> To answer your question: air (but all the arcing and sparking is
>> inside the pump with only liquid fuel).

> How about at the final few minutes of running out of
> fuel?

Pumping section (gerotor, turbine, or roller vane section as the case
may be for a given design) of the pump is below the commutation section.
Check valve in the fuel line keeping the pump full of fuel after pump
is shut off. There will always be a column of liquid fuel above the
pump commutation level.

> How about turning on the ignition (running the pump
> for a few secs) when the tank is "empty" ?

See above.

> How about a flaw in the diptube?

See above. It may be that no single-point of failure will cause a
problem. But, as with any system, you can hypothesize a **combination**
of failures that would creat a problem (cutting the odds) - you'd have
to argue whether or not such a combination of failures was credible.
And statistically, those combinations *will* happen. Don't ask me why
there haven't been real "unexplained" explosions.

> I'm gonna respectfully suggest that were I given
> a choice; I'd take a pump in the engine compartment
> (the other side of the firewall being a nice side
> effect bonus)

Too much heat - fire and vapor lock potential in the modern engine
compartment.

I hear you though. Do a google search on my name and
rec.autos.makers.chrysler and "commutation" and you'll see that I was
asking the same questions of Ford and Chrysler engineers when I was an
engineering manager for fuel pump products as a supplier - you'd be
surprised how many of them never even thought to ask the questions -
it's just the way things were done since before they were hired, so they
never thought about it.

I often said it to them, and I said it in this ng, that if in-tank fuel
pumps had not been invented before now, and I thought of doing it, I, as
an engineer, never would have suggested it in today's legal and
corporate environment - I would have kept my mouth shut for career
protection.

Actually, I seriously doubt that it would be being done now if it had
not had several years of being done with no indication that it was a
real problem. IOW - you could never prove, in theory, to a committe of
lawyers, managers, insurers, and MBA's that there could never be a
scenario that an explosion could not occur from some credible
combination of (1) running the tank out of fuel and (2) a bad in-line
check valve in the lines (allowing the liquid to drain back), and (3)
someone turning the ignition key to "run" and the fuel pump running dry
inside. Oh there will always be those who will have some explanation of
why it could never really explode - but wipe out their knowledge that it
has ever been done before and put them in the parallel universe where it
has not been done before and ask them to be the first person to
volunteer to sit in the first vehicle in which it was ever to be tried
the first time it was cranked up, and see if they will do it. Everyone
has great hindsight knowing that it is in reality apparently safe. But
to know ahead of time for sure...?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

Ken Weitzel wrote:
>
> Bill Putney wrote:
>
>> Ken Weitzel wrote:

>>> I do have one question though that I'd like to ask if
>>> I may? When I have a quarter tank of fuel left, what
>>> exactly occupies the remaining space?

>> If I see where you're going with this, the inside of the fuel pump
>> (where all the electrical commutation/sparking takes place) is 100%
>> full of liquid fuel under all conditions. Missing only one ingredient
>> for fire or explosion: air/oxygen. Comforting thought, eh?
>>
>> To answer your question: air (but all the arcing and sparking is
>> inside the pump with only liquid fuel).

> How about at the final few minutes of running out of
> fuel?

Pumping section (gerotor, turbine, or roller vane section as the case
may be for a given design) of the pump is below the commutation section.
Check valve in the fuel line keeping the pump full of fuel after pump
is shut off. There will always be a column of liquid fuel above the
pump commutation level.

> How about turning on the ignition (running the pump
> for a few secs) when the tank is "empty" ?

See above.

> How about a flaw in the diptube?

See above. It may be that no single-point of failure will cause a
problem. But, as with any system, you can hypothesize a **combination**
of failures that would creat a problem (cutting the odds) - you'd have
to argue whether or not such a combination of failures was credible.
And statistically, those combinations *will* happen. Don't ask me why
there haven't been real "unexplained" explosions.

> I'm gonna respectfully suggest that were I given
> a choice; I'd take a pump in the engine compartment
> (the other side of the firewall being a nice side
> effect bonus)

Too much heat - fire and vapor lock potential in the modern engine
compartment.

I hear you though. Do a google search on my name and
rec.autos.makers.chrysler and "commutation" and you'll see that I was
asking the same questions of Ford and Chrysler engineers when I was an
engineering manager for fuel pump products as a supplier - you'd be
surprised how many of them never even thought to ask the questions -
it's just the way things were done since before they were hired, so they
never thought about it.

I often said it to them, and I said it in this ng, that if in-tank fuel
pumps had not been invented before now, and I thought of doing it, I, as
an engineer, never would have suggested it in today's legal and
corporate environment - I would have kept my mouth shut for career
protection.

Actually, I seriously doubt that it would be being done now if it had
not had several years of being done with no indication that it was a
real problem. IOW - you could never prove, in theory, to a committe of
lawyers, managers, insurers, and MBA's that there could never be a
scenario that an explosion could not occur from some credible
combination of (1) running the tank out of fuel and (2) a bad in-line
check valve in the lines (allowing the liquid to drain back), and (3)
someone turning the ignition key to "run" and the fuel pump running dry
inside. Oh there will always be those who will have some explanation of
why it could never really explode - but wipe out their knowledge that it
has ever been done before and put them in the parallel universe where it
has not been done before and ask them to be the first person to
volunteer to sit in the first vehicle in which it was ever to be tried
the first time it was cranked up, and see if they will do it. Everyone
has great hindsight knowing that it is in reality apparently safe. But
to know ahead of time for sure...?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

On Fri, 29 Oct 2004 23:37:38 GMT, Ken Weitzel >
wrote:

>
>
wrote:
>> Perhaps if your degree was in electrical, rather than mechanical,
>> engineering you might. One reason is liquids can not burn. By
>> being inside the tank, there is no possibility of a combustible
>> mixture or fire. If for example the electric fuel pump were
>> outside the tank, in the line, there is a much greater
>> probability of a combustible mixture occurring in the event of a
>> fuel leak. OK?
>
>Hi...
>
>I'm electrical - but sure not interested in taking sides
>in this conversation.
>
>I do have one question though that I'd like to ask if
>I may? When I have a quarter tank of fuel left, what
>exactly occupies the remaining space?
>
>Ken

Fuel vapour in a concentration much to rich to burn. (in other words -
mabee a teensy weensy little bit of air mixed with a LOT of raw fuel.

On Fri, 29 Oct 2004 23:37:38 GMT, Ken Weitzel >
wrote:

>
>
wrote:
>> Perhaps if your degree was in electrical, rather than mechanical,
>> engineering you might. One reason is liquids can not burn. By
>> being inside the tank, there is no possibility of a combustible
>> mixture or fire. If for example the electric fuel pump were
>> outside the tank, in the line, there is a much greater
>> probability of a combustible mixture occurring in the event of a
>> fuel leak. OK?
>
>Hi...
>
>I'm electrical - but sure not interested in taking sides
>in this conversation.
>
>I do have one question though that I'd like to ask if
>I may? When I have a quarter tank of fuel left, what
>exactly occupies the remaining space?
>
>Ken

Fuel vapour in a concentration much to rich to burn. (in other words -
mabee a teensy weensy little bit of air mixed with a LOT of raw fuel.

Bob wrote:

> "Thomas Moats" > wrote in message
> ...
>
>>The same sheet-metal that makes the "fire-wall" also separates you from
>>the fuel
>>tank.
>
> Due to the lawyers I don't believe we have firewalls any more...... that
> would insinuate that a fire is possible. They are now called bulkheads.

Heh heh! Reminds me of the time in a presentation to NASA when I got
reprimanded for referring to an activation switch on a joystick for a
robotic arm to be used on the space shuttle as a "dead man switch" (this
was a few months after the Challenger disaster). (After the meeting, I
very quietly joked to a co-worker, "Hmmm - maybe I should have called it
a "dead *astronaut* switch?", insinuating that the objection was to the
use of the politically incorrect word "man" instead of the generic
"person" or "astronaut".)

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

Bob wrote:

> "Thomas Moats" > wrote in message
> ...
>
>>The same sheet-metal that makes the "fire-wall" also separates you from
>>the fuel
>>tank.
>
> Due to the lawyers I don't believe we have firewalls any more...... that
> would insinuate that a fire is possible. They are now called bulkheads.

Heh heh! Reminds me of the time in a presentation to NASA when I got
reprimanded for referring to an activation switch on a joystick for a
robotic arm to be used on the space shuttle as a "dead man switch" (this
was a few months after the Challenger disaster). (After the meeting, I
very quietly joked to a co-worker, "Hmmm - maybe I should have called it
a "dead *astronaut* switch?", insinuating that the objection was to the
use of the politically incorrect word "man" instead of the generic
"person" or "astronaut".)

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

Matt Whiting wrote:

> How many cars have you heard of that have exploded or caught fire from
> an in-tank fuel pump? In my case, the answer is zero so I don't lose
> much sleep over it.

Well *sure* you say that *now*. But would you have wanted to be the
first engineer in history to propose doing that? 8^)

> I'm more worried about an inadvertant air bag deployment than I am about
> my gas tank exploding. The former is much more likely than that latter
> and I've heard of several occurrences of unintended airbag deployment.

Can't argue with that.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

Matt Whiting wrote:

> How many cars have you heard of that have exploded or caught fire from
> an in-tank fuel pump? In my case, the answer is zero so I don't lose
> much sleep over it.

Well *sure* you say that *now*. But would you have wanted to be the
first engineer in history to propose doing that? 8^)

> I'm more worried about an inadvertant air bag deployment than I am about
> my gas tank exploding. The former is much more likely than that latter
> and I've heard of several occurrences of unintended airbag deployment.

Can't argue with that.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

Why do you think I put the quotation marks around the phrase fire-wall? It's not
a fire wall. But that is what most will call it, sort of like using the word
Kleenex instead of facial tissue.
"Bob" > wrote in message
...
>
> "Thomas Moats" > wrote in message
> ...
> > The same sheet-metal that makes the "fire-wall" also separates you from
> > the fuel
> > tank.
> >
>
> Due to the lawyers I don't believe we have firewalls any more...... that
> would insinuate that a fire is possible. They are now called bulkheads.
> Bob
>
>

Why do you think I put the quotation marks around the phrase fire-wall? It's not
a fire wall. But that is what most will call it, sort of like using the word
Kleenex instead of facial tissue.
"Bob" > wrote in message
...
>
> "Thomas Moats" > wrote in message
> ...
> > The same sheet-metal that makes the "fire-wall" also separates you from
> > the fuel
> > tank.
> >
>
> Due to the lawyers I don't believe we have firewalls any more...... that
> would insinuate that a fire is possible. They are now called bulkheads.
> Bob
>
>