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From: Norm of Bandersnatch (no email)
Date: Wed Jun 07 2006 - 10:29:09 EDT
The Tank Tender is simply a low pressure gauge, valves to select which tank
to measure, and a source of air, either a hand pump or a regulator
connected to an air line.
The system works by pumping air into a tube that goes to the bottom of the
tank until the air bubbles out. The gauge measures the pressure required
push the liquid down and out of the tube to do this. The pressure required
is directly related to the depth of the liquid. When the air bubbles out
the pressure stops rising and you read the gauge. For water this would
read about a half a pound for each foot of water depth. You have to make
calibration charts, psi vs gallons, for each tank.
This system need not be expensive. One could easily purchase a low
pressure gauge (one psi for each two feet of deepest tank) from
McMaster-Carr or equivalent, get a valve manifold from a aquarium supply, a
12vdc compressor from an auto store and a regulator from say Harbor
Freight. You should use stiff tubing so it won't balloon when you pump the
air in. Nylon air brake tubing would be good and cheap. I imagine
everything would be less than $100.
A little 12 volt compressor is good for lots of things. For example, to re
pressurize 2 liter Cola bottles. Put a tire valve stem on a Cola cap.
After pouring some Cola and replacing the cap feed air in with a tire chuck
on the hose. The pressure is about 25-30 psi. The bottles can take about
75-100 psi (re: Myth Busters). Blowing out small places when fixing things
is another biggie. Can't hardly overhaul a carburetor without air.
Norm
S/V Bandersnatch
Lying St Augustine FL
> [Original Message]
> From: Rosalie B. <>
> To: Live Aboard TORONTO <>
> Date: 6/6/2006 9:26:36 AM
> Subject: Re: lv-ab: Tank, Fluid Level Gauges
>
> On Tue, 6 Jun 2006 07:25:01 -0400, you wrote:
>
> >I stand corrected......It wasn't the Tank Tender I was thinking of.
There's
> >another system which uses sensors on the sides of plastic tanks which
senses
> >fluid level. The system's name escapes me at the moment.
> >
> The Tank Tender works on compressed air and so the composition of the
> tank has no bearing on it at all.
>
> >You're correct in that Tank Tender may be used on aluminum tanks. But
it's
> >an extremely expensive system.
>
> Yes - Bob said we paid $600 for ours and it had only 4 sensors -
> that's why we didn't also get the holding tank included. He says it
> is probably $800 by now.
>
> We use it a lot though. We did it because the fuel tanks are under
> the helm seat and we have to take that apart to stick the tank, and
> the water tanks are down in the engine room.
>
> You do have to calibrate the gauges yourself.
>
>
>
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