Why are water tanks horziontal?

[derjack]

center of gravity is NOT everything

The center of gravity argument always comes- though its not so important! Just notice how heavy Sportsmobile roofs are and some people put even some additional stuff on it!

When it comes to drivability there is a more important point:
Most of these PE tanks do not have any structure inside. I have never seen just one. This means: If you have 150l (40 gallon) in a half full tank, this mass is moving!
there is absolute uncontrollable 150kg of mass moving from right to left, front to rear....

the bigger this surface is, the worse it is!

in gas tanks you normally have an additional structure to prevent the fluid from moving, not so in PE water tanks.

 

[rayra]

You're discounting / ignoring that those van rigs are heavy all over, so the top weight isn't as disruptive. But it all depends on what sort of terrain exertions you are gonna make. Having a tank up high were gravity does the flow work is a nice thing. If you don't tip over on the way to the place you need a shower at.

And the word you are missing is baffles. Easy to add if you are building a custom aluminum tank out of plate metal, as with many expo trailer builds. Almost all these poly tanks are blow / roto-molded, just not going to get a baffle in there. Unless maybe you roll up some sort of honeycomb material and shove it in thru a fill port. hmmmm.

 

[rayra]

Thought I had a good idea, turns out I was reinventing the wheel - 'baffle foam' already is a thing

http://www.atlltd.com/blue-baffle-foam-diesel-water-methanol-use.html

 

[brianjwilson]

Yes a baffle would be helpful but I wouldn't put foam in there. You're just giving so much more surface for bacteria and gunk to hide and grow.

I think water would pass right through a screen, but a thin solid piece of plastic or something might have some effect? I've never found sloshing to be an issue in a 20 gallon or smaller tank though, myself. The weight shift is so smaller in a little tank like that, and I've certainly never felt it especially being low and between frame rails.

 

[rayra]

roughly 8-lbs / gallon. Can't be ignored if a person plans to put water up high.

simple to treat the water if you want to retard growth of anything in your potable water tank. You use dry granular calcium hypochlorate, essentially pool shock but be sure to get the brand that doesn't have other additives or colorants.

Welded aluminum tanks usually just have walls / baffle partitions with a pass-thru hole in each at the bottom. The trick is finding somethign that will work the same as a retrofit to a roto-molded poly tank. I can think of several solid objects that could be folded and inserted, much like a stent. sectioned PVC pipes to turn the whole thign into a honeycomb of sorts. Or fan-folded sheet products that can be compressed and shoved thru a fill hole, to fill the volume. But all of those are loose and will knock around and make noise. Foam is the one thing that won't.

There is no perfect solution, just compromises you can live with. And if people have OCD or phobias or some other mental barrier to a non-metal barrier, then just don't do anything. But I won't waste time arguing with them. I have no delusion about satisfying all things to all people all the time. I'm looking for technical solutions, not social ones.

 

[Thelgord]

I think the reasons already stated are a big part of "tank design". Mostly, in that there very limited horizontal space. By placing the tank under the trailer/rv this space can be used for things like shelves, stoves, chairs, etc...

Starting my own trailer build, the idea I came up with, is horizontal. 8" diameter PVC pipe at 12" long is roughly 603.2 cubic inches (exterior dimensions I realize). This is roughly 2.6 gallons. I can fit 6 of these side by side under the floor of the trailer, but still above the frame, for roughly 15 gallons. Make this arrangement 2 deep and I get roughly 30 gallons of water storage. I can feed each "tube" to every other tube with a fairly small pipe (say 1/4") and have them all connect to a slightly larger pipe (say 1/2") for the actual usage feed. They can be top filled fairly easy. This provides not only "baffles" of a sort, but in event of a puncture I can just shut off the damaged tank. Well ... that's the theory anyway...

[edit for spelling]

 

[IdaSHO]

And the word you are missing is baffles. Easy to add if you are building a custom aluminum tank out of plate metal, as with many expo trailer builds. Almost all these poly tanks are blow / roto-molded, just not going to get a baffle in there. Unless maybe you roll up some sort of honeycomb material and shove it in thru a fill port. hmmmm.

Whiffle balls work great for custom tanks.

Ive built a couple of water tank using 8" diameter PVC, and fill the entire tank with whiffle balls.

Fantastic baffles

 

[MagicMtnDan]

Tanks are typically made for industrial use and the form factor power equipment and other consumers of tanks need is low/horizontal.

Vertical tanks are available and shouldn't cause any issues at all but they're not as popular as low/horizontal FF.

 

[ZeneralGod]

*Mount the floor as low as possible, with LARGE cut-out wheel wells.
*Use unimog portal axles or planetary axle for better ground clearance.
*Mount underfloor heating elements.
*Have the water tank made out of stainless, flat and covering the entire floor of the INSIDE of the camper.
*Use welded baffles both to control sloshing AND for floor support to walk on.
*Your tank IS your floor.

 

[Mwilliamshs]

*Mount the floor as low as possible, with LARGE cut-out wheel wells.
*Use unimog portal axles or planetary axle for better ground clearance.
*Mount underfloor heating elements.
*Have the water tank made out of stainless, flat and covering the entire floor of the INSIDE of the camper.
*Use welded baffles both to control sloshing AND for floor support to walk on.
*Your tank IS your floor.

Need lots of custom fab time ($), a sump, and to always park with the proper end uphill. No thanks.