Lucked into two used 500 gallon propane tanks that I’m now considering hooking up to my (soon to be purchased) tarm 40/60 for use as pressure tank(s).  Couldn’t believe my luck when I approached the guy and asked him how much he wants for them and said “take ‘em, do you need me to drop them off for you”?

Now, not to look a gift horse in the mouth, but other than filling them with compressed air and seeing if they will hold the pressure, anything else I should do to them to get them ready?  Do these things corrode on the inside? and can I assume that if they will hold 30lbs of pressure there is not much else to worry about?

Just curious, what are the rough dimensions of those, and how much do they weigh each?

I didn’t measure them (and they are not here yet), but one is about 10 feet long, the other about 12-14. Less than 3 feet in diameter; not the same size. They’ll be here later this week, and I can give precise measurements.

anything else I should do to them to get them ready?  Do these things corrode on the inside? and can I assume that if they will hold 30lbs of pressure there is not much else to worry about?

Glad you got the deal - you won’t be disappointed. Check for the mercaptan odor in the tanks. If there, do what you can to rinse out, clean the tanks, and do it outside. Any mercaptan water spilling in the install location will carry the smell for a long time. Once closed and pressurized, no problem.

You might want to use a high temp filter or filter screen in the beginning to catch any rust, crud in the tanks. After being used for awhile you will know if you need to continue to use the filter.

When you fill the tanks for use, be sure to check pH. You will need to add boiler chemical to get the pH into the 7.5 - 9 range. This is a big deal, as acid water will corrode the steel and you will get lots of rust. You may want to add an O2 scavenger as well, although any dissolved O2 will be quickly consumed in a sealed system. Once pH is stabilized and O2 is consumed, the water will stay clear with no rust.

For 1000 gal you will need a big pressure expansion tank. I have an Amtrol SX-160.

My tank was trouble free, I didn’t even pressure test it.

Yes, I was warned about the smell. I am going to open them up at the far end of the fields (1000+ feet from the house) and let them air for a bit.

As far as expansion tanks, I checked out your Amtrol SX-160 and will likely order it or an equivalent one.

The expansion tank is none-ASME - I’m under the impression that I don’t need an ASME certified tank (luckily because they run around $3000), where would someone need a ASME certified tank?

Also, found this expansion tank size calculator on line for anyone that is interested: http://www.watts.com/pro/divisions/watersafety_flowcontrol/support/support_ETsizing.asp

Using my defaults 1100 gallons, max temp 205, 12 psi supply pressure (which I think is right??), I came up with 86.1 gallons. I may use ne of the 86 gallons tanks above plus add a small tank (under $100) to give me a bit extra buffer just in case that max temp gets higher than 210).

Also, I am really on the fence with the Solo 40 versus the 60. Now that my tanks will be very inexpensive to setup, that $600 difference in price seems like nothing. Any reason not to go with the Solo 60 if I will have 1000 gallons of storage on hand? I’d like to add a loop someday for the greenhouse (would run in March/April when the worst of the house demand is over). Are there other factors to consider when choosing between the 60 and the 40?

Need to order one today or tomorrow so last minute advice would be much appreciated....

Hi guys im just curious there isnt any danger of explosion using tanks that had propane in them?  Your not needing to do welding on them to add connections to the tanks??

MrEd - 14 May 2008 06:08 AM

where would someone need a ASME certified tank?

Not within my knowledge.

Using my defaults 1100 gallons, max temp 205, 12 psi supply pressure (which I think is right??), I came up with 86.1 gallons. I may use one of the 86 gallons tanks above plus add a small tank (under $100) to give me a bit extra buffer just in case that max temp gets higher than 210).

Realistically it is unlikely in my experience that the whole tank/system will reach your high point. My tank end point usually is 170-180 at the top and 150-160 at the bottom. The Tarm is set to idle at 190. Nothing prevents using higher numbers for calculation purposes.

Also, I am really on the fence with the Solo 40 versus the 60.

I think the best way to decide is to do a heat calculation and size the boiler accordingly. The tank is your heat buffer so that the Tarm can burn full out as much as possible. You will find that as the tank delta T starts to equalize, the Tarm will still go through idle cycles, as it will be producing more btu’s than it can transfer to the system. In this regard, if your boiler is over-sized you will be idling more often, which ideally you want to avoid.

mpilihp - 14 May 2008 07:09 AM

Hi guys im just curious there isnt any danger of explosion using tanks that had propane in them?  Your not needing to do welding on them to add connections to the tanks??

i have cut dozens of them for different uses and all i do is completely fill them with water to evacuate the gas. drain off the water and all that is left is the smell.

My hope is to use the existing fittings to do the plumbing that I need (not sure if that is possible or not). In the case that I do need to have fittings cut/welded on, is there any special precautions that need to be made? (Besides the fire danger I mean, water in the tank seems like a good idea). My concern would be that if a cut/weld is added to the tank, it might not handle the pressure as well as the pre-manufactured/factory controlled welds that are done. Would any competent welder be able to handle that job (my own welding skills are limited).

Also, when draining the stinky gas and remnants of whatever is in the tank, is there any concern that the discharge will be hazardous/toxic? or can it be dumped on the ground (far away from the house)?

I’ve been told that you can add a gal of bleach and that will neutralize the smell. I hope so as I have found a scource of tanks that I will be fixing up for storage that I will be putting up for sale this summer.
leaddog

My tank had plenty of fittings to meet in and out with no welding. I pulled water from the drain fitting in the bottom and added water in one of the top fittings. There were several top fittings plus one top dip-tube fitting.

Thanks just curious something to keep in the back of my mind, look for a used propane or milk tank never know when a good deal on one will show up or even a free one.

MrEd - 14 May 2008 08:04 AM

My hope is to use the existing fittings to do the plumbing that I need (not sure if that is possible or not). In the case that I do need to have fittings cut/welded on, is there any special precautions that need to be made? (Besides the fire danger I mean, water in the tank seems like a good idea). My concern would be that if a cut/weld is added to the tank, it might not handle the pressure as well as the pre-manufactured/factory controlled welds that are done. Would any competent welder be able to handle that job (my own welding skills are limited).


Also, when draining the stinky gas and remnants of whatever is in the tank, is there any concern that the discharge will be hazardous/toxic? or can it be dumped on the ground (far away from the house)?

ive taken some of the welds apart with an arc gouger and believe me, any competent and most incompetent welders can do as good a job!

most LP tanks have a good assortment of connections.  All the ones I have worked with have drain connections at the bottom and an assortment of top connections.  You can always build a dip tube to drop in a top connection to eliminate any cutting into the tank.

The float gauges can also be removed and used as a 1 or 1-1/4” FIP connection.

Getting the smell out was the biggest hassle for me.  It just took a long time for the flush water to lose the smell in my driveway.  Do it far away.

There may be some oily liquid in the bottom, capture it and take it to a recycler of an auto parts store to dispose.  No sense in dumping it on the ground, it just ends up in the water supply somewhere.

hr