An additional consideration that I need to mention, and which is covered in detail in the Safety Warning section at the top of the Mongo Burner information, regards UV radiation hazard. The Tweco tips increase the efficiency of the burners and their output temperature. In the Mongo burners the temperatures are up into the middle UV temperature color range, and it is possible to get flash burns from the light coming out of the forge. Be aware of this potential hazard with any burner you modify to use this tip. UV radiation is very damaging to eyes and skin.
I used four Reil burners on my 24 long cylindrical forge, but two or three are all that is necessary, and two will probably be enough in most cases. I live at an elevation of 2300 feet, and I can easily weld with only one burner running at 6 psi propane pressure. They are also being used successfully at over 7000 feet elevation, and they can weld easily at that elevation. If you would like to see more images of this forge, please go to my Forge and Foundry Page. Thank you.
Please note that Robert uses the burner in a cast iron and aluminum melting furnace, not a forge. You will want to operate at much lower pressures for forge work. Note: From tests done by Michael, it appears the Sidearm design is not a good choice for the smaller Micromongo and Nanomongo burners. He was unable to achieve a stable flame over a range of gas pressures in his Sidearm Micromongo test burner.
3. Shoot for a burner to volume ratio of 1:300 or less. Some smiths who are very knowledgeable would say a more conservative ratio of 1:250 would be safer and insure that your forge will be able to weld. To calculate how many 3/4 burners you will need just divide the total chamber volume of your forge, in cubic inches, by 250 or 300, and then round up. If you come out to a burner requirement of 2-1/3 burners, then you will need 3 burners for your planned forge volume. Always plan conservatively or you may end up with a forge that is too cold to forge-weld.**