REFLECTOR: Leaking sump float switch

[Chuck Jensen]

            For continuous readout-any length, any depth, another
solution is the Centroid Skyprobe.  They will manufacture to any length
and the electronic guts are in the head and output 0-5v.  They plug
right into the Grand Rapids, and probably any 0-5v indicator.  A little
pricey at $95/ea, but seem to be fool-proof, which is why they worked
for me. http://www.centroidproducts.com/tableofc.htm
 
            Chuck
 
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Alex Balic
Sent: Monday, October 10, 2005 12:09 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Leaking sump float switch
 
Gems sells a solid state unit that uses light dispersion to tell if
there is fuel at the sensor- you can get normally open or normally
closed types -  no moving parts and it will screw in as a direct
replacement for the float type switches. In my former life as a
manufacturing engineer- we went through several plants  on equipment
re-design replacing float types with the non- contact types- the floats
were leaking and sinking and causing all kinds of problems as a result.
 
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Jim Sower
Sent: Sunday, October 09, 2005 2:40 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Leaking sump float switch
 
If I had it to do over (which may very well develop) I would dispense
with the float switch (more of that 1920s technology) and install one of
the many solid state sensors available like those used for the low fuel
warning lights on our dash boards.  If I thought it important to know
how far into my sump fuel I am, I might mount several of these sensors
"on a stick" and have them drive ladder lights on the panel.  
Arguably cheaper than float switch, certainly safer and more reliable
... Jim S.

wurzel at alumni.caltech.edu wrote: 
So, I started noticing blue dye down the side of (and on the
floor right underneath) the sump tank.  Turns out fuel is
leaking either through or around the float switch.  D'oh,
the one-day annual condition inspection morphs itself
into a full-on project.
 
Unfortunately, my float switch isn't screwed into a hard point
as seems to be the standard these days.  I'm not sure if
Rick L rolled his own low fuel sensor, or if Velocity
used to recommend just glassing the switch directly into
the side of the tank, but in any event it is, in fact, just
glassed right into the side and providing a lovely 100LL
aroma to my cabin.
 
So, I'd like to convert this to a threaded installation.
 
1) Any ideas on the easiest way to do this?  My current
thought is to remove the current switch while taking as
little of the surrounding material off as possible.  Then,
sand the outside of the sump tank so it's flat in the area
where the switch was.  Next, coat the hard point and the tank
with epoxy and press them together... finally put some glass
over the outside of the hard point as well (making sure not to
get any in the threads!)
 
2) What do I need to know about fuel and epoxy?  Is there a
particular epoxy I need to use for this application?  Flox?
Micro?  Do I have to put some kind of sealant on the inside
after the epoxy has cured to prevent leaks or deterioration?
I saw some comments in old posts on using a shop vac to draw a
vacuum and suck the epoxy in around things, and that sounds
like a good idea as long as I'm using the right epoxy and it
doesn't dissolve as soon as the fuel hits it.  :-)
 
Thanks in advance for the help!
 
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