# Cleaning propane tanks



## waterflea (Jul 26, 2008)

I'm getting 3-500 gallon used propane tanks. I'm told that the insides are not so clean.
How are these tanks being cleaned out and made ready for use?


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## Ron Lloyd (Jul 26, 2008)

I just picked my tanks up from the welding shop. I also have three 500 gallon tanks. I’m not sure if it will work or not but I intend to use a high pressure washer. I may even see if I can purchase a long extension for the wand to reach in further. I have holes in each end and some holes in the center so I may be able to reach everything without an extension. I will probably pick them up from the end with my tractor and loader so that the debris will run out the other end as I spray. This is all just theory. I’ll let you know how it works out.

Ron


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## rreihart (Jul 27, 2008)

Ron,   If you don't mind me asking, where did you get your tanks?

Thanks,  Rob.


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## jebatty (Jul 27, 2008)

Be very aware that waste water from your tank cleaning may be ripe with mercaptan and oily residue, and that anything it gets on (ANYTHING) will smell very bad for a very long time. Clean far away from anything. You also might inquire of a local LP company as to the hazardous waste possibility of this water. The sewer or ground may be a very poor place to dispose of this water, especially if there is much oily residue in your tank.

I spilled water from my "new" tank on the floor of my shop, that was 4 months ago, and the smell is still strong, although less than initially. Maybe in a year or two (not kidding) it will be gone. 

That said, my tank was quite clean from a visual inspection. I installed an in-line hot water filter on the return side from the tank to the boiler, and I let the hot water clean the tank with the filter catching the crud. After a couple of filter changes, the filter now remains essentially clear. The hot water also seems to have broken down the mercaptan, as water samples (to test for pH) have no odor at all.


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## pybyr (Jul 27, 2008)

I was thinking of used propane tanks for a while- and googled around for the health and hazmat characteristics of mercaptan, and the results were sufficiently un-pretty (central nervous system depressant that in significant exposure can mess up your breathing & other vital functions, and seemingly almost certain to be significantly toxic to anything that ingests it when it's dissolved in or carried by water) that I concluded, as jebatty said "The sewer or ground may be a very poor place to dispose of this water, especially if there is much oily residue in your tank"  

In fact, I decided that for me, I did not want to deal with the health or liability aspects of having a bunch of mercaptan released on my property from cleaning out a used tank; 

Everyone's got their own individual set of risk tolerance and living/neighbor situations, so I am not saying that my conclusion should be the same conclusion for everyone- just some factors to consider in making your decision.


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## MrEd (Jul 27, 2008)

Everyone needs to decide for themselves what they are willing to be exposed to, but all of those symptoms you mention are probably much more likely to occur just by pumping your own gas at a gas station.

Here is a link to the CDC sheet on it - they don't make it sound all that bad - especially in the minute amounts you are likely to encounter when cleaning a tank.
http://www.atsdr.cdc.gov/tfacts139.html


As a comparison, here is one for gasoline:
http://www.atsdr.cdc.gov/tfacts72.html

Between the two, gasoline sounds worse - if I spilled a pint of gasoline on my property, I wouldn't think much of it. I did my best to capture any dregs that came out of my propane tank, but if a bit got spilled, I am not going to worry about that either. The smell was the bigger concern and it didn't take long for that to dissipate.

Not trying to talk anyone into a tank if they don't want one...but nor would I want to scare people off from using one when chances are the average person brings home a larger quantity of dangerous chemicals just by doing the grocery shopping at Walmart.


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## waterflea (Jul 27, 2008)

Thanks guys for the heads up. It sure is something to think about.


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## mtnmizer (Jul 27, 2008)

I was talking with my propane supplier about cleaning out a tank
of mine and using it for water storage, when he made a  comment
 that was interesting.  

  Apparently mercaptan will break down very fast and easily
by common soil enzimes/microbes. 

 While doing propane deliverys one day,
his (the propane guy)  coveralls got sprayed badly while hooking up the hose
 and he was not able to wash out the odor,
even after repeated washings (don't use your home washing machine). 

 He was advised by his boss at the time,
 to bury them in the  ground for a few days, then wash them.  He claims
that complety got rid of the mercaptan odor.

  Sounds possible.  I know for a fact that skunk odor can be completly
removed with a solution of hydrogen peroxide and baking soda.
I've also heard that bleach will do the same for mercaptan as will
hydrogen peroxide.

  I'd be interested in hearing from someone qualified about 
neutralizing mercaptan odor..dig a pit in the ground and run
the wash water into it? Repeated chem treatments?    MM


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## Ron Lloyd (Jul 28, 2008)

rreihart said:
			
		

> Ron,   If you don't mind me asking, where did you get your tanks?
> 
> Thanks,  Rob.



Rob,

Here are a couple of previous threads concerning places to buy used propane tanks in the south central Pennsylvania area.

https://www.hearth.com/econtent/index.php/forums/viewthread/18711/

https://www.hearth.com/econtent/index.php/forums/viewthread/19547/

The three tanks that I got from Mr. King had very little smell to them and once the welder was done with his work there is no smell at all. No oily residue either. The tanks are far from clean inside which is why I want to use a high pressure washer on them. I don't know if all of Mr. King's tanks are odor free to the same degree. Some of them look much newer and probably have more odor. After hearing some of the stories about mercaptan I'm very glad I don't have to deal with it. I paid $200.00 each for the ones I got. I don't know if he would sell just one that cheap or if he was giving me a discount for buying three.   

Ron


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## Ron Lloyd (Aug 1, 2008)

I used the high pressure washer on the inside of one of my tanks yesterday afternoon. It worked well and I was surprised at how much gunk came out. I’ll bet I could have filled a quart jar with it. The tank looks good inside now but I will still install some kind of filter in the system. It was no problem standing the tank on end outside but I have yet to figure out exactly how I’m going to stand it up once it’s in the building. They won’t go through the door vertically. A combination of chain hoist, block and tackle and a comealong I guess. Any tips would be appreciated. The picture on the right is the gunk. That’s a quarter lying on the 4 x 4 for size reference. I’m guessing I’ll get that much out of the other two tanks also.

Ron


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## Willman (Aug 2, 2008)

What is your ceiling height where tanks are going? I'm with you on vertical install. Space saving as well as stratification performance. All the euros seem to go vertical.

Grab the tank dead center in the horizontal position, raise up and then counterweight the end going down. Have another come along for the lowering. What will hold it upright ?
Will


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## Ron Lloyd (Aug 2, 2008)

Will,

I have a full 12’ ceiling height in the section of the building that the tanks will be in. The tanks are approaching 11’ with the truck rims welded on one end. You can’t see the truck rim very well in the picture above because it’s in a shadow. The truck rims will be the primary thing keeping the tanks upright but I may also anchor them to the wall using the set of feet that end up at the top. Some sort of pivot arrangement might work for getting the tanks upright inside the building. I’ll have to give that some thought.

Ron


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## chuck172 (Aug 2, 2008)

You guys might think I'm nuts but I have an Idea. I'm thinking of getting a 500 gallon propane tank. Only 1 for this year. I'll cut the dome off of one end and weld a 3/8- 4'X4 plate on it. I'll be able to pressure wash the inside. No mercaptan. End to end measurement will be about 9'. My basement ceiling joists are 9'6". I'll weld in couplings. Plenty of extra that I can always plug.
I'll have an auto-vent, anode tapping, plenty of gauges etc.
The advantages are:
better stratification
No smell
It will only take up a small corner space.

I'll be able to insulate the bottom, the plate will extend so I can anchor it down to the slab if I need to.
I can be smart and get one 1,000 gallon tank and cut it in half and have two tanks and be done with it.


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## flyingcow (Aug 2, 2008)

I'm sure you've figured this out, but I gotta point out you'll have 4,000lbs+/- of weight in just water.  :gulp:  Wouldn't be pretty if the base of these tanks fail. We're they designed to stand on end?


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## chuck172 (Aug 3, 2008)

Pressure is pressure. The tanks are pressure tested to many times what they will be put through. I'm more afraid of  2 1/2 tons of weight on a 4X4' section of  a 4" concrete slab.


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## Willman (Aug 3, 2008)

> I’ll cut the dome off of one end and weld a 3/8- 4’X4 plate on it.


Anybody know what  the metal thickness is on theses tanks ? Does it vary from the dome ends to the cylinder itself  ?
Will


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## rreihart (Aug 3, 2008)

Flat ends are not a good idea on a pressure vessel.  The ends are dished for a reason.  You may want to ask around before pursuing that route.


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## kabbott (Aug 3, 2008)

chuck172 said:
			
		

> You guys might think I'm nuts but I have an Idea. I'm thinking of getting a 500 gallon propane tank. Only 1 for this year. I'll cut the dome off of one end and weld a 3/8- 4'X4 plate on it. I'll be able to pressure wash the inside. No mercaptan. End to end measurement will be about 9'. My basement ceiling joists are 9'6". I'll weld in couplings. Plenty of extra that I can always plug.
> I'll have an auto-vent, anode tapping, plenty of gauges etc.
> The advantages are:
> better stratification
> ...



A flat plate on the end is not a good idea for a pressurized tank.At 15 psi a 30" dia tank will see about 10,000 pounds of force against the end.
A flat plate will bow outward even if it was 1/2" thick.


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## Willman (Aug 3, 2008)

> I have a full 12’ ceiling height in the section of the building that the tanks will be in. The tanks are approaching 11’


Ron, 
Not a lot of wiggle room. You might have to get out the grease   Any chance of cutting off rim and re weld when tank is upright, to give you a little more room ? You will definitely have to do some vertical bracing to floor joists if you are gonna use them for chain fall. I would build a steel lifting rig, but then you will lose some height, unless you can put the cross beam up into joist bay. Any way your in for a challenge. It will be worth it though.

Will


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## chuck172 (Aug 3, 2008)

kabbott, That's hard to imagine. Would you explain that in more detail?


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## kabbott (Aug 3, 2008)

Area of a 30" dia circle is 706.5 sq inches(pi x radius squared=3.14x(15x15)=706.5)
At 15 psi that comes to 10,597.5 pounds(706.5 x 15 psi)

I do underground utilities and when we test water lines most are required to hold 200 psi.On a 24 inch line thats about 90,000 pounds trying to push the cap
off the end.I have seen them fail, It will make you a believer.


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## chuck172 (Aug 3, 2008)

I have worked on 36" and 42" cooling tower lines. I have welded hundreds of these joints. That's the biggest pipe I've worked on.  I never had a problem.
I just don't understand how cutting the dome off and replacing it with flat plate, pressurizing it to 30#'s is gonna create the astronomical pressures that your talking about.


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## DaveBP (Aug 3, 2008)

Many conversations have been roadblocked by confusing the terms "force" and "pressure". Force is just "push". If you're talking vertically just think of it as weight. Imagine holding a 5 pound steel bar in the palm of your hand. One end of the bar is flat and the other end is sharpened to a pencil point. Either way, it puts 5 pounds of "force" on your palm. Flat end down is comfortable enough but with the pointed end down and you'll wince a bit. When you spread that force over a larger area the same force creates a lower "pressure"; pointed end down that force makes a very high "pressure".
    Fluids and gases crammed into a tank equalize their push against the all the walls. Take a hydraulic bottle jack as an example. You push down the long handle on a small cylinder. Say for simplicity, the leverage in the handle pushes down with 100 pounds of "force" on that little cylinder that has a surface of 1 square inch area. The fluid will go into the larger cylinder and push with that same 100 pounds of force on each square inch of of enclosing wall (100 PSI). If the larger piston has an area of 10 square inches there will be 1000 pounds of force on the cylinder face. Now you have 1000 pounds of "force" lifting up, not 1000 PSI of "pressure".
     That propane tank is the same thing. If you're pushing water into it with 30 lbs. of force per square inch (30 PSI) there is 30 pounds of force on every square inch of the tank wall. Do the arithmetic on a 1000 gallon tank. About 172 sq. ft.  area (for a 42" dia. tank) is about 25,000 sq. inches times 30 PSI makes about 3/4 millions pounds of force trying make that tank bigger than it started. The beauty of cylindrical and spherical shapes is that they turn those forces into stretching forces with no bending. That's why tanks are round shaped. Steel is way stronger in stretch than it is in bend. Flat ends will try to bend into a spherical shape. When you weld a flange onto tanks and pipes the flat cap on the flange is always much thicker steel than the cylindrical walls are for that same reason. 
    Picture a 1" wide section of the proposed 1/2" flat end of this tank. If it's 42" dia. you'll have a 1/2 x 1 x 42 long bar of steel laying flat. Now support it on the ends. 42 sq. in. x 30 PSI is 1260 pounds of force (weight) across the bar. That bar is going to bend. A round flat plate is more complicated than a rectangular bar but you can see how it is likely that that tank is going to lift right up off the floor. The fun part is imagining the leverage this kind of force has pushing against that large area across the narrow width of even a large weld bead. 
    I think the safest thing to do is to cut out a band of the cylinder and reweld the spherical head back on to make it the required length.


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## chuck172 (Aug 3, 2008)

So you're telling me that if I weld 3/8" plate on the bottom of a tank 9'high, although I'll only have 20psi from the system, and .433 pounds of water weight per foot, using 70,000 pounds of tensile strength welding rod, the tank will end up looking like a hot dog!


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## 2.beans (Aug 3, 2008)

about all the bad stuff in propane tanks. does anyone cook with propane? i know its being burnt but its still there. not trying to change the topic just my thought.


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## DaveBP (Aug 3, 2008)

No, Chuck, I don't think it will end up looking like a hot dog. But it will have nearly 15 tons of force pushing that flat end out and it will dish (I don't know how much) and that will put forces on the welds that they aren't designed to take. They wouldn't need to fail explosively to ruin your whole week. A leak is as bad as a flood in January. Rereading your post I realize you don't need to shorten the tank. Cleaning the inside of the tank is a great idea and I would like to pressure wash mine as well before I use them. Looks like Locust Loco cut a hole in the end and used a long wand guessing from the photo. Being you're experienced with heavy welding why not just remove and replace the round head. With spherical ends these things will tip up within vertical clearance about their overall length. With a 4ft. square end it might not clear your ceiling before it gets vertical. The shells on some modern 500 gallon tanks are about 1/4" thick if they are about 36" dia. The heads are 1/32" or so thinner. Old ones are made of thicker plate, I think; at least mine are (40 years old). I'm limited to available equipment. My tractor won't quite pick  them up vertically and I only have gas welding gear so I'm not confident to do it myself. I have access to the welding shop and welder at work (he welds the housings of some the biggest gear boxes in the world). I envy you guys with real tools. How do you plan to add a 2nd tank later? Drain the system and weld them together with some kind of pipe or just threaded pipe fittings? I keep tossing back and forth on this one. I have two 500gal tanks now and am expecting that's all I need.


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## chuck172 (Aug 3, 2008)

After giving it more thought I'll do the job the right way. I'll remove a piece . and reweld the dome. I'll then fabricate some type of legs for it. Thanks for all the good advice.


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## pybyr (Aug 4, 2008)

I'm neither an engineer nor a welder, just someone who wishes I was and has dabbled in both on a DIY level... if vertical space is a constraint, what if you cut one end's dome off, and inverted it into the open end of the tank, so as to get a flat bottom, but the strength that goes with the curve; as I understand it, an inverted dome is nearly as strong as a regular dome, and I recall seeing old "range boiler" tanks built in such a manner (inverted dome on bottom)


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## chuck172 (Aug 4, 2008)

That's exactly the advice I was given on a welding forum recently. 
I must say that this whole storage concept has been a royal P.I.T.A
I have never changed my mind, or had my mind changed by good advice so many times before. I hope I have the good sense to wait till next winter and burn without storage one year. Like I had originally planned.
I was told that this September, Tarm will begin selling storage tanks. I have also heard that they will be very expensive. I think the indoor swimming pools with the golden coils that STSS sells are just unbelievably high priced.


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## pybyr (Aug 4, 2008)

Chuck-well, glad I inadvertently offered something confirmed useful  

Yep, storage is the hard nut to crack; I went to Tarm USA in early June, and saw the prototype pressure vessels, and they'd never fit in my sub-7 foot 1830 house basement- looked like they'd need an 8 foot+++ headroom cellar clearance.  Good thing for stratification, bad thing if you can't fit it in the home you already own and want to stay in.  I am definitely going to go with a 6 x6 horizontal x 5 foot high 409 stainless bolted sectional tank + plate HX, because (A) I can get it into the cellar to install; and (B) it won't cost any more than an STSS + coils and will be a heckuvalot more bulletproof over the long run.  it'll take more careful planning for stratification than a tall vertically-oriented propane cylinder, but still oughta work.  I am working closely with a MFR on the basic layout and am more than happy to share details, as this is all to the good, for all of us, in the long run.


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## jebatty (Aug 4, 2008)

I can understand the anxiety, confusion, and excitement over storage, space requirements, engineering, plumbing, and operation. Two things stand out for me: 

1) Buffer/storage to allow a gasifier to burn full-out at maximum efficiency when heat demand is less than boiler capacity, or to store heat for future use.

Tank configuration to achieve maximum stratification is not automatically high on the list to meet this objective. A BTU stored is a BTU stored. Water volume as opposed to stratification is the prime concern. Space requirements, tank capacity, maximum tank heat based on tank material, open/pressurized tank, and insulation based on heated/unheated space seem to be the main issues.

As others have said, a heating system designed to extract useful heat down to 120F or so might be the ideal, as the system can deliver more usable stored BTU's per tank capacity the lower the design temperature of the system. Radiant systems can function down to this low temperature. My system is radiant, the tank itself is the radiator for the heated space (can't get more simple than this). Last winter it was uncommon for me to load the tank to higher than 150 at the top (130-140 was more common), bottom would be about 100-120.

2) Stratification to provide stored, usable heat for systems not designed for low temperature radiation, for dhw, or other uses requiring high temperature stored water. Vertical height and plumbing to minimize mixing of stored water would be key considerations, along with physical constraints of available space.

With an installed baseboard or water to air heat exchanger, there may not be many options here. For dwh though, I am perplexed by a general "need" for temps higher than 120. Most dhw recommendations are not more than 125, and some recommend less. 

As this forum draws lots of comments aimed toward achieving maximum stratification, with the resulting problems, maybe we need more comments on system designs or modifications that are not so dependent upon maximum stratification. This might provide options to relieve some of the stratification angst. 

In the end, we want BTU's, and the lower the usable temp the more BTU's we can store per tank capacity, and the simpler all of the issues become.


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## Willman (Aug 5, 2008)

> For dwh though, I am perplexed by a general “need” for temps higher than 120. Most dhw recommendations are not more than 125, and some recommend less.


Jim
DHW not hot enough can be a source of legionella. Google the term for more info.

Below from ASHRAE Journal, October 2007

Many guidelines recommend that the hot water temperature at the tank be 140°F (60°C) and the circulating hot water temperature be 124°F (51°C).16 Will this eliminate Legionella from distal outlets (faucets and showers)? The aforementioned study12 showed that peripheral sites remained heavily colonized despite elevated recirculation temperatures (>140°F [>60°C]). Legionella colonization was ultimately reduced in a Swedish hospital after it raised the temperatures even higher, to 149°F (65°C) at the tank and 133°F – 142°F (56°C – 61°C) at the outlets.17

Full article here. http://www.legionella.org/stout ashrae 2007.pdf

Will


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## Willman (Aug 5, 2008)

This is where the mixing valve comes into use, hot water to prevent legionella with mix valve for safety.


Will


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## jebatty (Aug 5, 2008)

No dispute that dhw can be a source of legionella. I need to consider this with a dose of salt, however, as home dhw systems through modern times likely have not met high temps and incidence of legionella is uncommon, to say the least. Our dhw never has been as high as 140.

I have no concern about door knobs, toilet seats wherever they may be, my kitchen counter at home, the common towel we use, the dish cloth for washing dishes, the shared water glass, taking care of snotty noses, kisses and hugs all the way around, and even not always washing hands every time after the bathroom stop. We don't use disinfectants or alcohol, no anti-bacterial soap, and stay as far away from antibiotics as we can. I'm for playing outside, healthy doses of dirt and crud, being around lots of people, getting the proper immunizations, eating good food, and building good immune systems.


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## solarvt (Aug 29, 2008)

Hello Everyone , lots of smart (experienced) people sharing ideas.  Im about to pull the trigger on a EKO25.  I have my sights on a 500 gallon LP  Currently we have BB DHW and the EKO will be our back , primary in the winter.  Need help in understanding if the water in the storage tank is only intended to go through a closed loop for my BB heat.  Or will this also be used for my DHW.   Seems like we don't want our drinking water going through the storage tank (please overlook my newbee questions.  I just need to get it straight.


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## solarvt (Aug 29, 2008)

Hello Everyone , lots of smart (experienced) people sharing ideas.  Im about to pull the trigger on a EKO25.  I have my sights on a 500 gallon LP  Currently we have BB DHW and the EKO will be our back , primary in the winter.  Need help in understanding if the water in the storage tank is only intended to go through a closed loop for my BB heat.  Or will this also be used for my DHW.   Seems like we don't want our drinking water going through the storage tank (please overlook my newbee questions.  I just need to get it straight.


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## solarvt (Aug 29, 2008)

Hello Everyone , lots of smart (experienced) people sharing ideas.  Im about to pull the trigger on a EKO25.  I have my sights on a 500 gallon LP  Currently we have BB DHW and the EKO will be our primary in the winter.  Need help in understanding if the water in the storage tank is only intended to go through a closed loop for my BB heat.  Or will this also be used for my DHW.   Seems like we don't want our drinking water going through the storage tank (please overlook my newbee questions.  I just need to get it straight.


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## jebatty (Aug 29, 2008)

Your heating water (tank and boiler) should be separate from your DHW. Use a heat exchanger to extract heat from the boiler/tank to provide heat for your potable DHW. Sidearms, plate and coil hx's all may be used and each has +'s and -'s.


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## DenaliChuck (Sep 8, 2008)

I just picked up my two 500 gallon propane tanks, they're a tad rusty, but in excellent shape overall.

A friend's dad who is a chemist just told me not to use bleach to clean the propane tanks because it will start a rapid rust reaction.  He suggested 2 gallons of denatured alcohol to clean the mercaptan out of a 500 gallon tank.

Also, remember that most landfills have a free collection day for household chemicals so don't dump the stuff or burn it off.


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## bernard (Sep 17, 2008)

Question on using the denatured alcohol to clean a 500 gallon tank
Must the tank be full of water and how long should the alcohol stay in?
Thank you


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## DenaliChuck (Sep 18, 2008)

The alcohol goes into the empty tank.  I drove around some bumpy roads with the tanks on my trailer to mix it well and soften any stuck on stuff.   They've been soaking for a week and this weekend I'll roll the tanks and drain the alcohol and mercaptan into a 5-gallon bucket.  Then I'll fill the tanks with water which displaces the remaining propane (which is heavier than air).  Then the fun begins with my 3.5" hole saw and lots of lubricating fluid!


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## chuck172 (Sep 18, 2008)

I just finished drilling and welding my tank. I used a 2" hole saw for 1 1/4" couplings. It went well. The tank wall thickness is 5/16".


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## DenaliChuck (Sep 18, 2008)

Chuck,

How long did it take per hole?  I assumed you used lubricating oil...and that the propane that seeped into the metal didn't explode ;-)


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## chuck172 (Sep 18, 2008)

The drilling went well. It took a while, broke a few pilot drill bits that are still in the tank. I'd say about 20 min. per hole.

I must admit I was scared. I flushed the tank 3 times. Welded with the tank just about full of water. I lucked out with this tank. There was no mercaptan, or propane odor to begin with. Very clean.
Before I struck the arc, I set off a bottle rocket with a delayed fuse into the tank. If the tank would have exploded I'd be history now, the delayed fuse part didn't work.


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## RJP Electric (Sep 18, 2008)

I did the same thing as chuck with the hole saw, but I had a professional welder mig welded the pipes for me. I have two 1 1/4 dip tubes on either side to pull up the return cold water evenly 3 inches off the bottom and I used the existing 1 1/4 in the center for my supply.

I brought it in yesterday and my plummer started to pipe it in. We love pictures here.
Oh make sure you have enough rear weight on your tractor, that tank is heavy.  It is a 1963 model, it held gas all these years but it looked like brand new inside.


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## DenaliChuck (Sep 18, 2008)

chuck172 said:
			
		

> The drilling went well. It took a while, broke a few pilot drill bits that are still in the tank. I'd say about 20 min. per hole.
> 
> I must admit I was scared. I flushed the tank 3 times. Welded with the tank just about full of water. I lucked out with this tank. There was no mercaptan, or propane odor to begin with. Very clean.
> Before I struck the arc, I set off a bottle rocket with a delayed fuse into the tank. If the tank would have exploded I'd be history now, the delayed fuse part didn't work.



Glad you made it!  The bottle rocket is a good idea, except for the bad fuse.  And no mercaptan is great, hope I luck out too.  I'm going to drill with the tanks full of water but I'm not too worried.  Going to get a local guy to do the welding for me - all I have is a little wire feed and he's got a big stick welder (and a lot more experience!).  He told me that anything above 15psi needs to be done by a certified welder, so it is good that my system will run at 14.5 psi ;-)


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## DenaliChuck (Sep 20, 2008)

Drained 2 gallons of denatured alcohol out of each of my 500 gallon tanks with no mercaptan noticeable, the liquid was a little rusty in color.  Filled with water to force out the remaining propane and drained.  The water definitely smells like propane (mercaptan) but the tanks appear clean inside.  They'll be welded and set in place tomorrow if all goes well.


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