Plastic Sight Gauges for Auxiliary Fuel Tank

Having had LOTS of experiences with sight guages on tanks.

Fuel, Oil, Water, Chemical, even seed tanks and fertilizer bins.

All seem to fog up and become unuseable after some time. Both from the material inside the tank and the elements outside the sight guage.

On the farm, we often use float type fuel guages similar to ones used on lawn mowers and boat fuel tanks.

Basically a float travels up and down a twisted rod to spin the fuel guage needle in the cap.

Have seen ones rigged to the sides of tanks as well.

Another option is a rod with a float at one end. With the proper seal, the further the rod sticks out of the top of the tank, the fuller the tank is.

Thanks Farmette however I'll have to pass on anything mechanical. The tank, once built, will not support easy access to the inside. Any mechanical system will require replacement or repair at some point and while they are usually reliable, (The Piper J-3 Cub and it's cork and wire float comes to mind) they are not always. Thanks L.J.

A pressure or weight guage may be a way to go?

Fiber-optic uses glass, which might be good for your use.

For cistern level I use a very low pressure gauge and a squeeze bulb and a plastic tube to the bottom of the cistern. It is very accurate and sensitive. The bulb likes to age and fail, and the cheap fittings come loose, but that can be remedied by using quality equipment. It's very simple, works something like a blood pressure gauge. The pressure gauge is not cheap.

I would think a simple graduated dip stick would be the cheapest and easiest way. If you know the dimensions of the tank, a dip stick is easy to calibrate. That's how I used to do it on my 30' Chris Craft cruiser with two 50 gal tanks.

There are loads of "dip sticks" on CR4 and the like, so you should get some good advice!!!

I have seen composite propane tanks that are translucent enough that you can just look. A light source on the other side could also help. Put a pushbutton on it so it doesn't need to be lit all the time.

Tornado wrote "I have seen composite propane tanks that are translucent. . . "

So have I! In fact 30 years ago I built a composite plane that had sight gauges made like that with clear epoxy.

I may go that route again but in the meantime, I've modeled the tank with perspex windows epoxied in place. Not my favorite method but it does work.

The design still needs a sump, course screen and fittings on the bottom and fixtures for attaching it to the package carrier on the motorcycles for which it is intended. The 4 gallon capacity is expected to extend the range by at least 250 miles, depending on engine size and driver technique.

Thanks for the support, everyone.

L.J.

Since this tank is intended to be used on motorcycles, don't you need to check with the DOT regarding rules and regulations for the transportation of flamable liquids upon public highways?

Sounds good but does the epoxy "FOG" up after time?

If it doesn't, may I try it on some of our farm machinery?

(after all it is your idea)

I have nothing to add, but the one really nice thing about sight gauges is that they never lie to you!

Why not just a polyethylene or polypropylene float inside a clear poly propylene fixed tube similar to what is on smaller lead acid batteries? Bioramani

Drill 2 holes, and put 2 elbows with a glass tube between them (or see through hose compatible with chem.)top to bottom on exterior?

Any external sight-glass should be installed with valves to isolate the sight-glass in the event of a failure of the component used, be it acrylic, pvc, or even glass unless you can have a little Dutch boy standing by to do his thing with his finger. The sight-glass should be well protected from any imagineable contact with anything which could cause its early demise, like a fork-lift, or a little Dutch boy with a hammer.

plastic have the aging problem.

If you go to WWW.PILLARPOINTELECTRONICS.COM you you will find a fuel system that uses a plastic rod as part of the sensing assembly for aircraft fuel systems. If the end of a tapered plastic rod is not immersed in fuel the rod has total internal reflections & light is reflected back out the rod. If the Plastic rod is totally immersed in fuel then light entering the rod from out side the tank is scattered into the tank & not reflected back out the rod. Sorry I do not remember the angle of the taper.

Doug

Dough wrote: "the end of a tapered plastic rod is not immersed in fuel"

That is exactly the principle I was referring to Doug. Thanks. I'll research this some more in an attempt to make a light array as discussed. In the mean time, the final design iteration has been completed.

Thanks for the link

L.J.

Normally the fuel will be a different temperature than the air space above the fuel. An indicator strip on the outside would let you know....

I have seen such strips used on propane tanks, temperature indicating labels, and many other applications.

Cheap. simple. effective.

Thanks Yusef.

That is a good idea in that no holes have to be made in the wall of the tank so the integrity of the container is improved.

However, composites like this one use cores made from closed cell structural foam to increase their strength. The insulating properties of the foam would interfere with the responsiveness of the strip.

L.J.

Some of the strips are really sensitive. They are used, for instance, to check for fevers on children...that is only a degree or two. Remember, insulation does not stop the transfer of energy, it only slows it down.

I really like the idea of a non-invasive strip....and one which does not stick out into the air beside the tank. An attitude which I have held ever since I swung a coffee cup in an ill conceived arch and cracked the sight glass of a coffee urn at a church function.

Anyway, that was just one idea among hundreds.

I used to spend hours in aircraft fuel tanks changing capacitance probes, so I am not a great fan of them...however they really do work well. Very accurate, very common, lots of people make them, easy to install, and resistant to all fuels. That might be a solution too!

Another idea might include fiber optic whiskers inserted into various levels of the tank. You would need some light into the tank (a window comes to mind, perhaps with an LED shining through it) and you can route the fiber optic whiskers up to a convenient spot. Such a system would be cheap, effective, work in the absence of electricity, and have zero moving parts. Whats not to like?