All,
Hey, what kind of pressure are we talking about here anyway? The reason
for asking is that if reasonably low enough, one could make a very
affordable tank from 6" PVC irrigation pipe.
I have one onboard our boat used for a different purpose and it was easy
as pie to make with end caps and glue. I've even very successfully drilled
into the side of PVC pipe to add another piece such as a fill neck and
outlet in the event of a person making a water storage tank for an
Airstream.
It would then be a simple matter of fitting an all metal valve stem to
the tank or whatever means is used to pressurize them.
Gerald, I'll even bet a feller could get all the parts from Mc
Master-Carr. ; - )
Flaws in my thinking anyone???
Glyn Judson
1969 Caravel #508
Santa Monica, CA
>> Hello All,
>> My '56 Caravanner water tank is galvanized steel, and of course, has
>> corrosion
>> holes in the bottom. I plan to have a duplicate made by a marine tank
>> fabricator in stainless. I think the concept of an air pressure driven water
>> system is elegant. No noise, no electricity. Maybe you all can give me your
>> opinion of an improved system I have in mind. I plan to add a small,
>> separate,
>> removable, pressurized air tank which I could fill in place or remove and
>> fill, then reconnect to the water tank. By using a pressure regulator between
>> the air tank and the water tank, I could fill the air tank to a much higher
>> pressure. Therefore, It could last quite a while providing the stepped-down
>> pressure to the water tank. For safety, and to depressurize the water tank
>> for
>> fillups, I'd add an automatic blowoff/depressurization valve (much like a
>> water heater has). This setup would also allow me to fill the water tank
>> completely and still have pressure. There's plenty of room for a small air
>> tank in a cradle under the couch with the water tank. Is there any reason why
>> this won't work? Also, Dr. Johnson, could you make a suggestion on an air
>> pressure regulator that would work in this application?
>> Brian Jenkins
>>
> Some Sears shop air compressors include such a pressure regulator. I
> didn't like the one I had though. Seemed to restrict air flow quantities
> too much. McMaster-Carr's printed catalog has pages of such air pressure
> regulators. I'd guess that a 1/4" pipe threaded one adjustable to 30 psi
> would be about right. Maybe 41735K44 with bracket 41735K48 and no
> pressure gauge. Or 4956K51 and 4957K61 or 4959K21 and 4957K61, the last
> one has a pressure gauge. None of these are expensive.
>
> I'd expect any tool store that sells air tools or air compressors will
> have a few pressure regulators available.
>
> Don't count on the regulator to be absolutely silent.
>
> It can be important to keep track of the materials in the compressor and
> the regulator. You don't want lubricating oil added to the water supply
> so especially the compressor should be made for the air tank
> application. Tire pumps will likely dribble a bit of oil.
>
> As for torch brazing a leaky aluminum tank, the "brazing" alloy is not
> pure aluminum, but mostly zinc, so it makes an impurity in the tank wall
> which speeds up future corrosion. That's not a permanent cure. Also the
> last of that that I used melted just a little lower in temperature than
> the base aluminum melted (and neither showed a color temperature) so it
> was easy to begin to get the brazing alloy to melt and start to stick,
> and then the whole project melted into a blob on the floor. When
> successful (that was on window screens) the brazing metal did contribute
> to visible corrosion.