bajones Posted May 16, 2013 Share Posted May 16, 2013 Hey guys I'm working on my first forge and decided on a 19 inch long steel mailbox for the body. I'm going to use one inch thick hard firebrick for the bottom and line the rest with Inswool and Satanite, and I am also spraying the outside with rustoleom high heat spray. I want to put coat it with ITC or Plistix at some point, but right now my budget doesn't permit that. Anyways, my plan is to use the existing holes in the bottom of the mailbox to bolt it to the top of a steel rolling cart with a shelf on the bottom that I can place a 20lb propane tank on and run a hose from it up to the forge. My question is, will that be enough insulation to keep from melting the cart? Thanks for any help. Quote Link to comment Share on other sites More sharing options...
Frosty Posted May 16, 2013 Share Posted May 16, 2013 Welcome aboard, glad to have you. If you'll put your general location in the header you might be surprised at how many IFI folk live within visiting distance. I don't know the width of the mail box but at 19" long it's going to need more than two 3/4" burners and a 20lb. tank will freeze up pretty quickly. If you put an inch of insulwool under the box, it'll keep the cart reasonably cool and NO, it isn't going to melt steel outside the forge. Get it hot enough to light things on fire maybe but not melt steel. It IS going to get the cart top hotter than a pistol though so you might want to put the forge up a few inches and make a helper to support long work. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
bajones Posted May 17, 2013 Author Share Posted May 17, 2013 Thanks, glad to be here. I've learned a lot here already. After I put in the insulation it'll be about 4" wide. What causes the tank to freeze? And how can I remedy it? Is 20lb the wrong size or do I need to put something on it? Thanks for all the help. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted May 18, 2013 Share Posted May 18, 2013 cooling is from gas exchange faster than the tank is designed for. Quote Link to comment Share on other sites More sharing options...
Frosty Posted May 18, 2013 Share Posted May 18, 2013 Propane is liquified petroleum gas and to draw it off it has to either evaporate, by boiling if drawn at a fast rate to maintain tank pressure. Boiling cools the liquid as only the most active molecules (warmest) evaporate leaving the coolest. A larger 100lb./25 gal. tank is how I keep mine from freezing on one or two burners. Still, on a cold day or 3-4 burners running I have to plug in two magnetic engine heaters stuck to it to keep it from freezing in maybe an hour or so. 4 burners will still freeze it and I have to put it in a half wine barrel I keep for the purpose. Cold water works fine, hot or even warm isn't necessary at all. As an alternative to buying a 40lb./10gal. tank or larger you can set your 20lb./5gal. tank in the slack tub. Water has a much higher specific heat than propane so it'll prevent it from freezing and maybe form a skim of ice on the outside of the tank. A dedicated tank warmer tub is a great place to keep pop/beer/etc. cool. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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