LP Tanks modified

[Chris S]

I brought home 1 LP tank today. A pretty, but smelly endeavor.
The tank a used 500 gallon skid type tank was evacuated months ago, and was sitting valve open for 5 months now.
I opened up all of the ports, and poured in 3/4 of a gallon of peroxide ( not enough apparently).
Filled the tank with water, then drilled 2- 2 1/2" holes with a hole saw, ground the paint down, and had the welder weld on the weld-o-lets.
Roll it over, let all the water out, onto the truck & off we go. I found my clothes outside the front door this morning- the odor still strong. At work, I still smelled mercaptin, and finally realized, some water must have gotten on my boots. One more tank to go, then...
We are having 2# polyurethane foam sprayed , so I will have the insulator spray 2" over the whole tank, after installing nipples, and pressure testing.
I haven't read here where anybody has done that yet, so I'll be sure to post pictures.
Chris

 

[sgschwend]

I am about to do a couple of tanks too. It would be good to here what the cleaning chemical requirements are.

Also are you using an input diffuser to keep the turbulence down?

 

[RobC]

search oxyclean there is a previous post. 2 tubs and wait a couple of days.

 

[sgschwend]

Sound like a lot more than necessary, the chemist should be able to estimate the volume for us.

What about the diffuser? Does anybody have an easy method of adding one?

 

[DenaliChuck]

Search my posts; a friend's father (a chemist) suggested denatured alcohol to clean propane tanks. IIRC I used 2 gallons for a 500 gallon tank.

 

[foche911]

What are you talking about?

 

[fabguy01]

I tried the oxy-clean method about a week ago and had little to no effect, Did a google on mercaptan and found that you need to oxidize the mercaptan to remove the smell household bleach is the most commonly used. so i added a gallon of clorox to about 1/4 full 500 gal tank well see if it works. I did fill a spray bottle with bleach/water solution and sprayed the outside of the tank,hands, and boots and it seemed to work

 

[sgschwend]

The active ingredient of Chlorox is sodium hypochlorite.

One caution is that the oxidized mercaptan is another acid, here is a reference:

From: Ask.com

Oxidation by more powerful reagents such as sodium hypochlorite or hydrogen peroxide yield sulfonic acids (RSO3H).

I would expect that you will need to fill the tank totally so that the oxidizer can reach all of the internal surfaces.

 

[Chris S]

One of my golfing buddies a retired chemist suggested clorox. So... I filled both my tanks with water & clorox. They're sitting right now, full. I plan to empty them tomorrow, but I will try the spray bottle with clorox on my boots etc. that still smell.
Also, I'll be able to report on the effectiveness of straight clorox with water vs lavender scent clorox with water

Stay tuned, Chris

 

[Gooserider]

No comment on the effectiveness of bleach on "gas stink" but if you are going to get bleach, this is what I've found using it this summer in my pool - which works great BTW...

1. Bleach is bleach - there is no difference in the stuff with generic labels vs. the big C brand name, other than scents (which you probably DON'T want...) and strength...

2. The Strength will vary... Most of the commercial stuff and the standard Chlorox bottles is 6% - some of the generics can be as low as 3% so check your strength when doing price comparisons

3. It supposedly doesn't keep - the bleach starts to break down after a while, and the effective concentration will drop - this can be a big problem with the stuff in the "dollar stores" - a lot of it is old stock that has been relabled.

4. General concensus on the TroubleFree Pool website is that the best store price for 6% is Walmart's house brand.

5. You can get stronger - many, not all pool stores will carry stronger "liquid shock" - often 10-12% purchasing it by the gallon it's usually more expensive than the 6% WallyWorld stuff, but you can also get 5 gallon plastic carboys, which IMHO are a good deal... I've been paying about $22 / carboy, of which $5 is a deposit, so the real cost is around $18, or about $3.50 / gallon of 12%, or the equivalent of $1.50 a gallon for 6%, and without generating all the plastic garbage, or carrying an extra 5 gallons of water home from the store...

No idea what strength or quantity would be needed to clean out a gas tank, but I'd expect it would be enough to justify getting the carboys.

Gooserider

 

[fabguy01]

Well, I added 2 more gal of bleach. after rolling the tank around to get loose gunk dislodged a couple times a day I emptied out the bleach and filled with clean water overflowed it for about a hour. emptied it and to my supprise IMHO it worked quite well "waaaayyy beter than the oxiclean". I set up a old blower from a house forced air furnace to circulate air and try to dry out the remainder of the water overnight. came home from work today and couldent smell the propane unless i was within 5 feet of it. Went inside and got some fabreeze like stuff by Renuzit<? Took it out and sprayed about 10-15 squirts through the blower and it totaly eliminated the smell ! We'll see if it holds overnight

 

[pybyr]

If the goal is to oxidize the mercaptan- which is what I gather from the discussions about using chlorine bleach-- what about trying to get some of the 30% hydrogen peroxide that's sold as a commercial pool treatment/ shock for people that are using the non-chlorine-based pool water treatment systems (Baquacil and similar products/ systems)?

 

[sgschwend]

If you purchase a higher concentration of the oxidizer you can reduce the amount you need. I am pretty sure you will find that the best price will be the stuff purchased from a grocery store.

 

[Piker]

I used the oxyclean method... which worked fairly well... at first. Before i treated the tanks with it, I acutally spent about an hour pressure washing the tanks out to make sure I had as much of the Mercaptan out as I could get. When I put the oxyclean in, I used the pressure washer to make sure it was mixed well as I was filling up the tanks. When I drained the tanks a few days later, there was very little smell.

All that having been said, the oxyclean did not apparently get all of the mercaptain taken care of... Now with the system pressurized and having sat for a few months, when I take a water sample from the tanks or if I get a little air out of a vent I smell the mercaptain. I noticed when cleaning the inside of the propane tanks that there is a thin black scale inside of them... my guess is that this scale absorbes the mercaptan, making it difficult to remove the odor without removing the scale.

Luckily the odor of the water doesn't really pose an issue in a closed system... except when you're doing maintenance. I would not want to get any of this water on the floor in basement for fear the smell would leech into the concrete and never come out. Since this is my own system, I know enough to be careful with the smelly contents... but I would never install used propane tanks on a customers system. Would I do it again for myself? yeah probably... it saved me about $2k.

Spray foam contractor will be here in a week or so to coat the tanks... can't wait.

cheers

 

[fabguy01]

Well, I added 2 more gal of bleach. after rolling the tank around to get loose gunk dislodged a couple times a day I emptied out the bleach and filled with clean water overflowed it for about a hour. emptied it and to my supprise IMHO it worked quite well "waaaayyy beter than the oxiclean". I set up a old blower from a house forced air furnace to circulate air and try to dry out the remainder of the water overnight. came home from work today and couldent smell the propane unless i was within 5 feet of it. Went inside and got some fabreeze like stuff by Renuzit<? Took it out and sprayed about 10-15 squirts through the blower and it totaly eliminated the smell ! We'll see if it holds overnight

Well Its bean a couple of days and the smell is almost totally gone you cant smell it with all the plugs out unless you are within just a few feet of it. next well se what happens when the hot water gets to it