Propane Bottles & Annealing

[Gordon Couger]

As run small Propane tanks a long time it gets colder and and as the liquid turns to vapor at -46 F. The colder the liquid propane the lower the gas pressure goes so less gas get to the flame so your brass gets less heat.

Setting the propane bottles in a pan of water and keeping the water at 70 F will let use almost all the propane no matter the size of the bottle.

 

[ronemus]

As run small Propane tanks a long time it gets colder and and as the liquid turns to vapor at -46 F. The colder the liquid propane the lower the gas pressure goes

Exactly! It's a double whammy because as the liquid level drops there is less cylinder surface in contact with the liquid propane to pull heat from the air; using a water bath gives you liquid-to-liquid heat transfer which is more efficient than air-to-liquid and so you see less pressure variation.

 

[XTR]

The theory is in a closed system at constant temperature were a substance, in this case propane, exists in both the gas and liquid phase the pressure is constant for a given temperature. What happens with the small bottles as the propane is used the conversion from liquid to gas is using the latent heat of vaporization. As the level drops there is less liquid and the temperature drop is more pronounced because you don’t have the heat sink of the liquid so the temperature in the bottles gets lower and the pressure gets lower, the flame gets smaller.

You will often notice the flames are a little less hot after 100 or so rounds some days too. That is the system coming to equilibrium with heat transfer from the surroundings.

 

[Plinkit]

You can got up the big box stores for a short length of water line next tracing that will give you a warmer to wrap around the tank if you desire

 

[JimSC]

back when I used to anneal with a Annealeeze, I only did a 100 at a time normally. I never saw enough of a drop over the 15 minutes or so it took to anneal to make much of a difference in flame length and I used the small dark green bottles made for the camping lanterns. If I had noticed any difference in flame length a simple valve adjustment would have solved it. Another alternative would have been putting a gas grill regulator in the line if I had ever felt the need to anneal batches of two or three thousand and wanted to walk away from the machine. I stopped annealing once I did some research on the metallurgy of the process but still have the machine just in case I ever decide to start again

 

[D-4297]

I found that as the bottle got used ; gently rocking , ( shaking ) the small green bottle for a couple minutes before hooking it up seemed to reduce the amount of torch adjustments during the run . I also do short runs of 100 - 150 with my Anealeez , and it has worked well for me .

 

[wkdickinson]

This may be a bit off topic, but may have some value to the discussion. A few years ago I retrofitted my gas grill with a two-stage regulator and it made an amazing difference. As has been discussed here with anealers, the grill heated differently as the propane cylinder got less full - input pressure to the regulator diminished as the propane level dropped and it was less able to overcome the spring pressure on the diaphragm. As I understand it, the pressure in a full propane tank is about 100+ psi and the regulator output to the appliance is about 10 to 11 in. of water (about .38 psi). The two-stage regulator reduces the tank pressure in the first stage to around 10 psi, which feeds the second stage, that then reduces it to the 10 or 11 in. of water. Which gives you a much more consistent pressure at the appliance as the propane level drops.

 

[JimSC]

Jim, I would love to know what information you found on metallurgy, that made you change your mind about the annealing process? Thanks

https://forum.accurateshooter.com/threads/to-anneal-my-brass-or-not.4023147/post-37955531

I annealed 100 6BR yesterday for my next match, working on getting that last 2%. Figured it might not help but it can't hurt either.I will wear my lucky hat also for the same reason