Will a metal fuel tank work for black/grey holding tank?

[Midwilshire]

Looking for the board's collective wisdom on using a 100 gal. metal diesel tank as a combined black/grey holding tank.  What corrosion or other issues might arise? 

http://tampa.craigslist.org/hil/pts/3458013662.html

[Mex-Busnut]

Several both here and on the school bus conversion net (http://www.skoolie.net/) have done exactly this.

Let me just suggest you think of sensors for monitoring your tank levels. You can use some brass screws, 4 or five inches long into the tank. Under the head of the screw, (outside of the tank) insert your terminal for wiring. Of course, the screws and terminals must be insulated from the tank, so use a rubber grommet and silicone well. You need 5 screws. The bottom is ground, so it CAN be connected to the tank uninsulated. Then one insulated screw at 25%, one at 50%, 75% and 100%.

This system will work with the simplest monitor panel which you can salvage from a junk yard RV from the seventies or off Ebay. Or if you are handy with simple electronics, build this inexpensive circuit. (Just add some more resistance in series with your 12 or 24 volt source to reduce it to 6 volts.) This one shows 6 sensors. you only need 4.
http://www.circuitstoday.com/simple-water-level-idicator

[TomC]

The reason this metal tank works with Diesel is the oil lubing effect from the Diesel coats the inside of the tank prevent rust from growing. Put water in and you'll have rust. Add in the VERY corrosive action of salty and ammonia urine, sulfur from solids mixing with water and the tank would quickly become a rusted mess. Just because others have done it doesn't mean it's right or correct. There's a real good reason waste tanks are made from non reacting plastics. Larger tanks on boats and ships are typically epoxy coated or just plainly fiberglass. A good plastic tank made for waste isn't much more then what they are asking for that metal tank. And the plastic tanks last a long time. I had a gray water tank last over 800,000mi of driving with it mounted on a piece of plywood that was on top of the fuel tank cross supports on my Kenworth just a few inches above the ground.  Good Luck, TomC

[Ace]

[quote water in and you'll have rust. Add in the VERY corrosive action of salty and ammonia urine, sulfur from solids mixing with water and the tank would quickly become a rusted mess. Just because others have done it doesn't mean it's right or correct.
[/quote]
Tom gotta say, thats funny!

How many people do you think REALLY roll down the road with tanks (any type) with waste?

With that said, how long is it gonna take to eat thru if the tanks are empty MOST of the time?

My suggestion is, go ahead, it WILL work with NO problems for many many MANY years, IF you remove any baffles from within the tank!
That goes for steel or aluminum!

If you plan on storing your crap and taking it with you on your highway adventure, you might be the type to travel with a deceased inlaw until you get back home... Just sayin




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[PCC]

Do fuel tanks not have an access port hole? Or you can create one.

Then could you not spray inside, if that is a concern, with a coating (like a Rhino lining)?

I don't know (because I use a 150 gallon plastic bladder waste tank), but I thought if I say something, someone will either correct my thinking, or agree with the idea !!

[TomC]

As I said, just because people use improper materials for tanks doesn't mean it is right. Yes it probably will last a few years. But I can tell you, getting a hole in the black tank ain't fun. On my truck, my black tank was (like my gray tank) mounted on the lower fuel tank cross supports just a few inches above the ground on a U bolted plywood. I also had the exhaust pipe running right next, which wasn't a problem since I had a heat shield. But-I blew an exhaust clamp off and the raw un muffled exhaust started escaping. It sounded really cool so I didn't do anything about it for a while. That is until I was pulling a hill and the hot exhaust melted a couple of the plastic air lines bringing me down to a rude and rather sudden stop when the parking brakes on both tandems set. Also, the heat melted the black tank. When the tow truck took us to the truck repair, while the truck was up in the air with the tow truck, I removed the melted black tank, and that was like dealing with nuclear waste it stunk so bad. Got the plastic air lines repaired and went on down the road. I still used the toilet without the tank-just put a pale under when parked and emptied it into a toilet. Always some sort of fun when traveling. Good Luck, TomC

[Lin]

Ace, I have to disagree on this one.  Once the rust starts, all it needs is air and the nice humid atmosphere in the tank and it will keep on rusting.  Yes, it will certainly take some time to go all the way through, but you will not be ready for it when it does happen.  If one is really committed to using fuel tanks, maybe it would be possible to coat the inside.

[buswarrior]

oh sh1t, here we go again...

Check the archives, this has been argued with great vigor a number of years ago.

With no resolution and a lot of angry busnuts.

happy coaching!
buswarrior

[Ace]

" the heat from the exhaust melted the black tank"

Just imagine the mess you would have had if your tank was metal! Heaven forbid!

Lin do you honestly think that IF a metal tank were to leak even 10 years down the road that its going to blow out like a tire holding air?
Trust me and agree or not, it wont be a gusher! It may develop a very small drip at most and if not cared for soon than yes, it will grow into a larger hole but definitely NOT a gusher that will drown you with your own waste!

If you plan on using fuel tanks from a semi, cut the end off and simply remove the baffles, then do as you should and dump before hitting the road and if parked in a campground, hook up your sewer hose and leave it open!
You will NEVER have an issue!


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[luvrbus]

Guys I have a 4106 here in the shop that 2 has round aluminum fuel tanks from a truck they have been installed since day one no I did not install the tanks but they look new and stuff is not running all over the floor lol  

[Red Rider]

Clifford, those tanks where installed in Nov of 1988.

[muldoonman]

Built 2 out of stainless years ago for my Boss's Prevost and he  went to a Industrial Coating place and had um coated inside. They were still on coach he sold 30 years later.

[Low Class]

"How many people do you think REALLY roll down the road with tanks (any type) with waste?"

The only times I dump the tanks away from home is if they are full and there is no choice.  Rest of the time I prefer to dump at home where I use a hose that I keep hanging on a shed.  This way, I do not have to deal with storing the nasty, stinky hose in a compartment.  With properly vented tanks, I haven't had any problems doing it my way.

Also, about 1/3 of my camping is where there is no place to dump.

[luvrbus]

Funny how Prevost will use plastic for the fuel tanks and metal for a holding tank on their seated coaches figure that one out lol

[belfert]

Built 2 out of stainless years ago for my Boss's Prevost and he  went to a Industrial Coating place and had um coated inside. They were still on coach he sold 30 years later.

Why would stainless need coating?  Will the waste still eat through stainless?  I'm thinking about a waste tank made of stainless and wasn't planning to coat the inside.

I have my waste tank full of waste for several days at a time.  We don't stay at campgrounds on the road and there is no reason to dump every time we get fuel.  We dump just before our destination and then boondock for four days.  Think about it, your tank is going to have waste on the bottom just about all the time the bus is in use unless you have sewer and run lots of water through.