Another storage tank option- I hope!

[pybyr]

With my Econoburn gasifier ordered, I now need to arrive at a plan for storage- which I want to be as big as possible, to maximize efficiency.

I've been leaning towards pressurized in the last few days, but am also beating my forehead against the constraint that my old house's cellar is accessible only via a bulkhead hatch 48 inches wide and about 5.5 feet long. I'd never get a 1000 gallon propane tank down it, and am not sure even if a 500 would slide in without running into things (I sure don't want to discover it won't fit after I bought it and have it halfway in!). Headroom is less than a newer house, too, so that all is starting to push me back towards un-pressurized storage, maybe with flat plate heat excehangers.

For open storage options, I know the STSS tanks are out there, and they're probably OK if you want an off-the-shelf ready-to-go unit, but after looking at them in person at Tarm USA, they just strike me as too Rube-Goldberg for my preferences, given their very substantial price tags).

So here's something I ran across that has me __really__ intrigued: A polypropylene modular septic tank, shipped as flat panels that are assembled on-site using stainless screws. Unlike a lot of the plastics like the more common polyethelene or fiberglass resin, Polypro _is_ rated to handle 200F heat for long periods of time. In digging around on tank manufacturing companies' online literature, I found that polypropylene tanks have been in use in some instances for decades at 200F temps for metal finishing tanks (full of caustic liquid) . So the polypro material seems able to handle the temperatures-- as long as the specifics (seals, etc) of this make tank are also up to it. I am going to contact the manufacturer to ask some more, but in the mean time, I wanted to "float" the idea here to get suggestions, constructive criticisms, and the like. I know I'll need to insulate, too, but can handle that separately.

so here's the scoop on this tank I'm looking into

(broken link removed)
and
(broken link removed)
and an article (skip the intros on other tanks and go down to the heading of "Copolymer Polypropylene tanks")
http://www.gradingandexcavation.com/ow_0507_septic.html

Again, please "fire away" with suggestions, observations, constructive criticisms, etc. Thanks, as always, for all the shared wisdom & ingenuity around this place!

Trevor

 

[free75degrees]

That looks like a very interesting idea. Do you know how much they cost?

They say on the site that they are very strong, but how about resistance to outward pressure? In a normal septic installation this isn't an issue since it is backfilled with dirt, so I wonder if they might have designed the structure with very little strength against outward pressure. Even if this is the case it is probably still worth persuing - you could always add your own structural support on the outside.

 

[pybyr]

yeah, I was wondering the same thing about resistance from inside pressure pushing out as compared to a septic tank's usual life of outside pressure pushing in. That's one of the things I am going to ask the manufacturer about. But I figure that unlike something like concrete, which has high compressive strength but poor tensile strength, the polypropylene, which is used in lots of other tank applications, should have strength in both directions. their web site says that they make tanks for other applications, too, so I am going to call them, hopefully end of afternoon, to find out about pricing and learn more in general

 

[sparke]

Good luck with E-Z Tank I tried reaching them a while back. I got nothing but dis-connected phone messages. I found another company that makes polypro. tanks. They wanted big$$ I forgot the amount. I basically put it out of my mind when the salesmen gave me the price. If I remember correctly it was $2800.

 

[DenaliChuck]

Anybody talk to these folks?

http://royalliner.com/

 

[pybyr]

Thanks Denali Chuck- tried calling Royalliner, and at least they have an answering machine.

Sent them an e-mail asking ball-park costs for a 48 x 60 x 60 tank; also sent a similar request via e-mail to a company in Rhode Island that also fabricates rigid polypro tanks

the search goes on...

 

[free75degrees]

You guys are driving me nuts! All of these great tank options after I already made mine with flat epdm.

 

[free75degrees]

I wonder if this stuff would work:
http://www.oxfordplasticsinc.com/hdpepipe.htm

 

[heaterman]

You're talking non-pressurized storage of course. Right?

 

[pybyr]

heaterman- yes, fully recognized that any of these tanks would have to be non-pressurized

free75degrees- well, you have something that works- so far, I just have ideas, and a lot of time and effort ahead, so you're doing OK and then some

the appealing thing about those polypropylene septic tanks is that they look like they were, or would've been, a relatively high-production/ modular item, thus taking them out of the spendy-specialized category

 

[Nofossil]

I looked at polypro tanks. I think it's a viable option if you can provide external support. I ended up with my stainless tank in part because it was cheaper.

 

[pybyr]

Nofo- who in VT did you get your stainless tank through?

As I try to look into all this, it seems like the upward spike in the cost of metals means that there are a lot fewer used tanks around (a lot have been sold for scrap or re-use), and the ones that are, people are asking a premium price (and then some!)

 

[mpilihp]

Hi all, I am also looking at storage tank options, I found this while browsing online, its a 500 gallon fuel tank used by contractors for site fuel. Appears to be fairly think steel. Too large to fit in the basement but could stack two on top of each other just outside of the house and insulate them..

I would be looking to use it as a pressurised storage tank, Im sure its not rated, any thoughts on it?

~ Phil

 

[pybyr]

Funny, Phil, that you mention the fuel storage tank, as the same thing crossed my mind (having seen them stacked outside a nearby petroleum supply wholesaler) once I recovered from falling over at prices of what salvaged stainless tanks are going for these days given the run-up in metals prices.

if you take a look at

(broken link removed to http://www.highlandtank.com/LIT/HT_Aboveground_Horizontal.pdf)

you'll find some interesting details on these above ground fuel-type tanks, which seem to come in an appealing array of sizes

and if you go to

(broken link removed to http://www.itanks.com/results1b.asp?CategoryID=24)

you'll see some prices for these, which, if they're current, look less astonishingly impossible than so many other things I've run across (exopecially given that this is new and other things are salvage) (note that the scrounge in me is still hoping I can come up with something that'll cost a lot less)

Available in several gauges, and the thicker gauges on the 500 gallon and bigger sizes are pretty thick

As to pressure rating, I am sure these are NOT pressure-rated in the sense that say a propane tank is. One of the install specs I ran across for these "Highland" tanks seems to indicate that they are pressure tested to 5psi, and that they suggest a test of not less than 3 psi but not more than 5 during install & check-out. But one would surely be asking for true catastrophe if you set it up in a way that it could end up pressurized.

This whole question of "what's pressurized" led me to post another thread about "semi pressurized" wondering if one can gain some of the benefits (nixing all the intermediary heat exchange stuff) while still keeping the PSI low enough that nothing will "go boom" I also really need to get comfortable that this type of "ultra low pressure install" would allow the system to operate under conditions in which it won't corrode out my new boiler, or cause one of these tanks to pinhole and fill my cellar with rusty water.......

 

[mpilihp]

Hi Trevor thanks for the info and comments, another possibility is to use the tank in an open storage setup, cut a big hole in it.... Ill take a look at your thread on semi pressurized.

Can anyone tell me what is the min pressure rating a pressurized tank needs to be rated for?

Anyone else have any comments on these tanks? Even for a non pressurized system the price isnt bad.

~ Phil

 

[pybyr]

Phil & all-

1) as far as I can tell, a non-pressurized non-stainless ferrous-metal vessel is the fast road to a leak and a flood- if you're going to go with non-pressurized, you need to have a containment vessel that won't rust out, and then you need a heat exchanger that will keep oxygen out of your boiler, so that the boiler does not rust out

2) end of the day today, I called Highland Tank, which makes the diesel storage tanks, and, if you wander their web site, all sorts of other tanks, including stainless tanks and pressure vessels. I outlined the "method to the madness" of thermal storage for a wood-fired gasifier. the fellow I spoke to was very helpful, and will be calling me back, ...he said..., tomorrow AM, with some more details of options and prices based on what I described. I also searched out and contacted the intellectual property law firm that did the patent application for the fellow (Harley Patee) who filed the patent application for the polypropylene "kit septic tank" that I'd mentioned at the top of this thread that seemed to have high potential for a non-pressurized storage tank, and left a message asking them to ask him to get in touch with me about the potential of that technology for thermal storage.

3) I'll keep y'all posted, and please do the same. this all seems like it would've been easier and more affordable a few years back, before metals prices did the run-up- but that's no reason to wait any longer (in fact the opposite!)

 

[carbon neutral]

I am planning on using ICF's. They can easily be brought into an existing basement and assembled in place. They make a very strong wall and if you are using icf's for your foundation (new build) you can get two of your four tank walls for free. They are made of polypropylene which can be a problem, according to wickapedia the glass temperature of polypropylene is listed as 95 degrees celcius. To ensure I do not run into a problem I will line the inside wallls of the tank with Polyisocyanurate Insulation which can handle much higher temperatures. With the extra insulation the R value would be about R-30. The icfs also have built in strips that you can use to screw plywood to, I plan on mounting all zone pumps, valves etc on the side of the tank to make good use of that wall area.
As far as cost there are several different manufacturerers of ICF's but the price is generally around $4/sq ft not including concrete. Concrete cost varies with area, in my area the cost of concrete delivered adds about $2/sq ft, with 8" thick concrete cavity. The tank I am planning will be 4'*8'*6'. Water level will be 5.5' yielding 1300 gal storage. Cost ~ 4*6= 24ft/sq + 8*6= 48ft/sq totoal wall area = 48+24= 72ft/sq, remember I get half my walls for free since I am integrating with my foundation. 72 ft/sq * ~$6/ft sq= $432, for an R22 tank. Add in the extra cost of polyisocyanurate insulation, and EPDM liner and the total cost will be close to $1,000, which I feel is cost effective when ease of installation and performance is considered, remember the finished tank will have approximately an r-30 value.
You cannot use these for a pressurized tank so if that is important to your installation this would not be an option.
Anyway of all the tank systems I have looked into this was the best option I have come up with. Hope it helps.