Propane Bottles & Annealing

[PMA3]

I did a Google search and couldn't find the answer so I'm looking to the "tech" oriented on the forum for help.
I use the standard 14 oz. propane bottles for running my Bench Source Annealer. I have noticed that as the propane bottles go from FULL to almost EMPTY (100% -25%), the corresponding "blue wash" gets higher and higher UP the case body toward the neck/shoulder junction.

My question is this: Does a FULL bottle generate more heat than a 25% full bottle or does the heat remain constant until the bottle is empty?

 

[dkhunt14]

It gets less as the bottle empties. I use Mapp and can really notice it. I have to change my time as the bottle empties. Some guys have went to the big tanks to stop this and refill before they are empty. Matt

 

[NoahbodyImportant]

Read this: http://forum.snipershide.com/snipers-hide-reloading/193306-bench-source-annealer-how-convert-yours-run-one-10lb-propane-tank.html

 

[PMA3]

Matt.....thanks for the reply. The info is consistent with what I'm seeing.
Noah...GREAT link....pretty much says it all and offers a in-depth solution.

 

[Mudcat]

I upgraded to a 20 pound tank like you would use on a grill. works MUCH better than the little bottles and I have yet to run out a 20 gal tank and have been using this one for well over a year and I anneal a LOT....figure I have done at least 20,000 cases on this tank so far.

 

[jonbearman]

With the 20# tank I am assuming you use it out in a garage? I don't think I would do it in a house due to propane being heavier than air and if it leaks,kaboom!

 

[TerryPohl]

I use the 20#er also, had to get a HP regulator but it works great, I use it in side but checked all fittings for leaks with soapy water after putting it together. No difference than a propane cook stove.
Terry Pohl

 

[Catfur]

With the 20# tank I am assuming you use it out in a garage? I don't think I would do it in a house due to propane being heavier than air and if it leaks,kaboom!

Use it in the house all you want, just don't store it there.

 

[amlevin]

No difference than a propane cook stove.
Terry Pohl

Except that propane cook stoves have their tanks stored outside if they are using the large "tanks".

The problem with the 20-30# propane tanks is expansion. If they get too warm the gas is vented through a pop-off valve and you can suddenly have a lot of explosive gas present. A larger problem when the tank is freshly filled but they don't belong in a house.

Yes, one can have an "accident" with the smaller "bottles" but at least the potential for damage is a lot smaller than if you have a 20# + tank present.

 

[TerryPohl]

I should have clarified my use of the 20# tank I use. I do use it in the house but do not store in in there, just bring in the tank and use it for the 1/2 to 1 hour it takes to do the job. ( My wife would have a cow if I tried to leave something non decorative in the house.)
Terry Pohl

 

[PMA3]

It looks like a lot of guys use the 20lb. tanks......but my question is still the same, whether using a 20 lb. tank or a 1 lb. bottle. As the volume decreases, does the flame produce less heat, thus providing a different annealing temperature on the case.

 

[Webster]

The small bottles don't have a pressure regulator. I noticed that the flame gets smaller when I have about a 1/4 tank left. I could use a flame spreader thats smaller than the one you get with a BurnzOmatic torch. The hottest area in the flame is very small. I am getting the necks much hotter than the shoulder with a single hand held torch. As the pressure goes down i would guess the flame has the same temp but the flame is smaller so you get a completly different heat distribution.

 

[dkhunt14]

I believe you are correct Webster. I said in an earlier post as my bottle empties I need to add more time. That means the flame is not as hot. I probably notice it more because I use Mapp and a little difference in flame probably shows more difference. Matt

 

[dkhunt14]

I put my heat on the body shoulder junction. I heat till the neck turns just a slight bit. When they are done the black ring goes down the body like a Lapua. If you watch the flame it will turn from blue to orange and walk around the case to the back side. When it does this it is done. Now I only have a machine with one torch and it might be different with a two torch setup. Matt

 

[PMA3]

rvn1968....As Matt stated above, the "blue wash" is the coloration appearing down the case body, below the neck/shoulder junction, like you see on new Lapua brass. The case head is the area you don't won't any high heat traveling to. On the Bench Source annealer, I have both flame tips hitting the neck about three quarters of the way down, just above the neck/shoulder junction.
Webster...sounds like you're saying that the 20lb. tank with a pressure regulator doesn't keep the annealing temperature the same as the volume gets lower in the tank. So, other than convenience, the 20 lb. tank and the 1 lb. bottles seem to work the same. I'm doing less than a 1000 cases/year so the propane cost for me is really a moot point. I think I'll stick with the small bottles (more convenient for me), monitor the annealed cases and switch out the bottles when I see a noticeable difference in the flame and "blue wash". I'll use this procedure to try to keep a consistent annealing temp on all cases.

 

[1066]

I don't think you can necessarily rely on the colour of the annealed case.

One thing I've noticed is, if I anneal a case straight after it's been cleaned (SS media) I get very little colour change, but if I anneal another case from the same batch after it's been standing around for a week in the open air I get a classic "Lapua" blue.

I also believe that if you get to the stage where the flame turns yellow, you've gone too far. As far as I understand, when the flame turns yellow it's because the zinc content of the brass is burning off.

If you are losing zinc, it's a one way ticket, the alloy balance is no longer 70/30 copper/zinc but something else.

 

[TominSWNY]

I was all set up to start annealing some 22 br cases yesterday. I have a 15 lb bottle that a bought last year with a splitter and hoses. Everything was set and ready to go when the flame went out. Hmmmm, tried to relight it and no go. Took the torch head off the hose and what do my fingers behold but oil. To has to be coming from the propane bottle. This is going to be tough to get any money back from blue rhino propane. Had to go back to the one at a time small bottle.

 

[Catfur]

It looks like a lot of guys use the 20lb. tanks......but my question is still the same, whether using a 20 lb. tank or a 1 lb. bottle. As the volume decreases, does the flame produce less heat, thus providing a different annealing temperature on the case.

The propane in the tank is under pressure and most of it is liquid. As long as some of it is liquid (and the temperature remains the same) the pressure will remain the same (as you drain off the gas, the pressure drops, allowing more liquid to boil off, keeping the pressure at an equilibrium point). The pressure doesn't decrease until you have all the liquid gone (at which point you are dealing with the last dregs of gas).

 

[Catfur]

The trick is keeping the temperature constant. The propane gets cold as the gas boils off, and with less fuel in the can the temperature drops more. I've set the bottle in a shallow pan of water (not hot water, just room temperature) to keep the pressure up as the tank gets low. It seems to help.

This phenomenon occurs over the course of a single annealing session (I've never experienced it, though it's certainly possible) however, not over the course of the life of the bottle.

 

[amlevin]

I also believe that if you get to the stage where the flame turns yellow, you've gone too far. As far as I understand, when the flame turns yellow it's because the zinc content of the brass is burning off.

If you are losing zinc, it's a one way ticket, the alloy balance is no longer 70/30 copper/zinc but something else.

Your're right about burning metal off but it doesn't take much to cause a flame to change color. The amount consumed in the second or so is so small it doesn't alter the alloy at all.

For my purposes I find that I don't need to heat so hot that I get flame color change but when it has happened it hasn't "killed" the case.