Capacitive fuel gauge...tank penetration

I'm working on putting a capitive fuel gauge into my welded aluminum
tank. In consideration of how to bring the wire from one of the plates
out of the tank...the best I've been able to come up with is to weld in
a 3/16" tube run the wire through it, and pack it full of a ProSeal type
epoxy. I'm wondering, is there a smarter way to accomplish the task?

I'd weld in a pipe coupling, and then screw into that a compressing
tubing connector, with the brass ferrel replaced with a fat oring that
would seal the wire.
tom


Ernest Christley wrote:
I'm working on putting a capitive fuel gauge into my welded aluminum
tank. In consideration of how to bring the wire from one of the plates
out of the tank...the best I've been able to come up with is to weld in
a 3/16" tube run the wire through it, and pack it full of a ProSeal type
epoxy. I'm wondering, is there a smarter way to accomplish the task?

wrote:
I'd weld in a pipe coupling, and then screw into that a compressing
tubing connector, with the brass ferrel replaced with a fat oring that
would seal the wire.
tom


Ernest Christley wrote:
I'm working on putting a capitive fuel gauge into my welded aluminum
tank. In consideration of how to bring the wire from one of the plates
out of the tank...the best I've been able to come up with is to weld in
a 3/16" tube run the wire through it, and pack it full of a ProSeal type
epoxy. I'm wondering, is there a smarter way to accomplish the task?


That sounds like a workable solution.

Another problem I encountered when rereading the article for the third
time, is that a little water or alcohol with seriously screw with this
circuit. I remember someone else on this very newsgroup suggesting a
second in-tank capacitor as the reference cap. I modified the circuit
to do this and posted it at

http://ernest.isa-geek.org/Delta/Lib...evelSensor.pdf

Other than making the reference section look exactly like the
measurement section, the only addition is a connector and the reversal
of U102A. Before, the reference was at 4kHz, and the measurement varied
from 4 down to 2 as the tank filled. Now, the reference will stay at 2,
but the measurement section will vary in the same way. This swap in the
input logic simply required a swap of the device itself.

Now if a little water or alcohol gets in the mix, the circuit should be
a little more resistant...as long as the contaminents stay in solution.
A pool of water in the bottom of the tank will make the gauge read
empty, even when my preflight of reading the sight gauge says the tank
is half full. That should go into the POH as a indicator that the tanks
need a little draining.

Is this clever, or just wrong?

1/4" hole in the tank top near an access hole should you ever have to get
into the tank to work on it.

Rubber or vinyl grommet into the hole.

#4 or #6 machine screw, large area flatwasher top and bottom, solder lug top
and bottom, locking nut on the bottom. Screw, solder lug, flatwasher,
through the grommet, flatwasher, solder lug, nut.

Solder capacitor wire to lug inside of tank and solder wire to rest of
circuit from top solder lug.

Jim

"Ernest Christley" wrote in message
...
I'm working on putting a capitive fuel gauge into my welded aluminum tank.
In consideration of how to bring the wire from one of the plates out of
the tank...the best I've been able to come up with is to weld in a 3/16"
tube run the wire through it, and pack it full of a ProSeal type epoxy.
I'm wondering, is there a smarter way to accomplish the task?

RST Engineering wrote:
1/4" hole in the tank top near an access hole should you ever have to get
into the tank to work on it.

Rubber or vinyl grommet into the hole.

#4 or #6 machine screw, large area flatwasher top and bottom, solder lug top
and bottom, locking nut on the bottom. Screw, solder lug, flatwasher,
through the grommet, flatwasher, solder lug, nut.

Solder capacitor wire to lug inside of tank and solder wire to rest of
circuit from top solder lug.

Jim


Perfect. I can place it right next to the filler port.

"Ernest Christley" wrote in message
...
I'm working on putting a capitive fuel gauge into my welded aluminum tank.
In consideration of how to bring the wire from one of the plates out of
the tank...the best I've been able to come up with is to weld in a 3/16"
tube run the wire through it, and pack it full of a ProSeal type epoxy.
I'm wondering, is there a smarter way to accomplish the task?

Ernest Christley wrote:
RST Engineering wrote:
1/4" hole in the tank top near an access hole should you ever have to
get into the tank to work on it.

Rubber or vinyl grommet into the hole.

#4 or #6 machine screw, large area flatwasher top and bottom, solder
lug top and bottom, locking nut on the bottom. Screw, solder lug,
flatwasher, through the grommet, flatwasher, solder lug, nut.

Solder capacitor wire to lug inside of tank and solder wire to rest of
circuit from top solder lug.

Jim


Perfect. I can place it right next to the filler port.

"Ernest Christley" wrote in message
...
I'm working on putting a capitive fuel gauge into my welded aluminum
tank. In consideration of how to bring the wire from one of the
plates out of the tank...the best I've been able to come up with is
to weld in a 3/16" tube run the wire through it, and pack it full of
a ProSeal type epoxy. I'm wondering, is there a smarter way to
accomplish the task?


Another thought would be to install a fuel proof cannon plug. Try:
http://www.spacecraft.com/

Dan, U.S. Air Force, retired