Perhaps not now but they absolutely did back in the 70's and 80's. The
brushes wearing out was a common cause of failure.
Even if they did, gasoline requires oxygen
Something has to displace gasoline as the tank emptys. Most every one runs
out of gaoline at one time or another and the fuel pump was exposed to air
when the tank was low on fuel.
I never really thought about it before, but with
Air displaces gasoline as the tank emptys or the tank would collapse.
Unlikely, very true but what keeps the brushes from causing an explosion?
IT'S MAGIC.. ;~)
The oldest submersed pump system I am familiar with is from the late
80s early 90s GM vehicles using throttle-body injection. Even
these systems manitained a constant fuel flow with a return line to
the fuel tank. As the return fuel is heated during its round trip,
pressure in the tank tends to rise due to increased fuel vapor
pressure. You have probably experienced the "poof" of escaping vapor
when removing a fuel cap. My understanding is that the pressure inside
the tank is largely from fuel vapor rather than air. The natural
tendency of the system over time is to exclude air from entering.
I do agree, though the idea of the electrically operated fuel pump
being inside the tank used to disturb me, however, either through
serendipity or design, I have yet to hear of a fuel tank fire caused
by an electric pump. And when you think about it (and I realize that
the current is limited to an extremely low value) the fuel gauge
system is electrically operated, with a sending unit inside the tank
that uses a contact that slides over a coil to make a variable
resistor. And that type of setup has been in use since before I was
born, let alone working on trucks.
Just as a possibly interesting story, I have been working in fleet
and mobile equipment maintenance for about 29 years now. I've seen a
few vehicles that caught on fire, some of them literally burning down
to the frame & chassis. I've only seen one fuel tank that had
combustion occur inside it without being damaged first. On this
particular vehicle, a pickup cab & chassis, a tech was doing some
welding in preparation of installing a utility body on the chassis. I
don't know exactly what happened, but there was a flashover of some
kind that caused a brief detonation of some sort inside the tank.
There was no external damage and no fire beyond the momentary "flash"
inside the tank. The interesting part is, that the tank "balooned"
somewhat as a result, but did not leak, and after the incident, it
held about 3 more gallons than when it was new!
Make it as simple as possible, but no simpler.
Larry Wasserman - Baltimore Maryland - email@example.com
This was 1975 GM carbutated. The X bodies in 1980 became some of the first
with fuel injection.
Agreed, however there would surely be times that a cap would be left off and
at least a few times air would enter.
IIRC the tank sending units had enclosed electrical for the float arm.
I was in the industry about 23 years and never saw a problem with tanks
either. I am missing something some where. I know that our factory rep
could not explaing how the fuel pump would not cause an explosion.
I'm not sure what that last sentence means, but I
suppose that it means that their is pressure in
the tank under normal operating conditions. That
is certainly true since at least the 1960's and
before fuel injection was common. The fuel cap is
made with a valve that prevents fumes from exiting
the tank but allows air to enter. This type of
cap prevents the tank from collapsing and also
results in water in the tank from cooling and
condensation of moisture from the air that enters.
I haven't a clue about the electrical operation of
the in tank pump. But even with a supposedly
empty tank (engine stops running) thee will be
enough gasoline to create a mixture of gasoline
and oxygen that is too rich to burn.
Before any one starts arguing, I and everyone know
that explosions and fires do occur around gas
tanks. But those occur when a tank ruptures, a
spark or open fire is at the mouth of the filling
hole, or a very small amount of gas is in the tank
when it is welded; all of those can provide at
least a pocket of gas/oxygen mixture that will burn.
Too rich to burn is real, but with all the possibilities...tough to figure.
Do know that fuelling accidents involving vapor pressure in gas tanks are
the reason we have to have diesel ambulances now. Can't use the "200
treatment" phrase any more- 100% oxygen 100 mph- because they just never
can get there. Used to be a bennie on a rural run.
So the car sits with the cap off for a week or two and someone gets in to
start the car.
There is more to it than a hopefully too rich mixture. Out of millions of
cars with this set up there are going to be a many chances offer the years
for many of them to have the right mixture.
Have to ask them, I was just taking this:
From the Manufacturer
This is an electric hacksaw for cutting pipe and profile steel when a
spark free environment is required. The saw will cut pipes up to 24"
in diameter and profile steel up to 21 3/4" height and 11 1/2" width.
The saw blade needs 6 inches of clearance to make the cut. A pipe
clamp is also recommended for cutting pipes.
off the website at Amazon at face value.
(Amazon.com product link shortened)69086724/ref=sr_1_628/104-7821139-9460756?ie=UTF8&s=hi
I was shocked by the price tag for something that my recip. saw could do.
And yes when is the last time you had a sawzall spark on you? Being that
there is ventilation for the motor, one would have to assume that either it
is made of some real high end materials (gold wiring, some advanced
titanium, carbon fiber body) or that the price is in error. Also I would
like to find the concrete and cast iron cutting blades for it.
I could see this as being spark free..
(Amazon.com product link shortened)69173627/ref=sr_1_153/104-7821139-9460756?ie=UTF8&s=hi
And sorry to our Canadian friends, it can only be shipped in the U.S.
Will your recip saw take a 37 inch blade for cutting over 20 inches of
As for the concrete and cast iron blades, it took me about 30 seconds
of searching to find sources--google "fein hacksaw blades" and you'll
get a link to the part numbers, google the part numbers and you'll get
links to suppliers. The short (20 inch) concrete blade is over 70
And there's no indication on the Fein site that either saw is "spark
The price appears to be because this is a honking big saw whose small
blades are about the same size as the biggest blades for a Sawzall,
and it's not intended to cut steel once in a while, it's intended to
cut it all dfay every day.
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