[TheForge] PING - terry ridder, et al --Propane forges

[Keporter at aol.com]

In a message dated 6/22/2005 4:55:40 A.M. Pacific Standard Time,  
jhusvar at sbcglobal.net writes:


I  was just wondering if I'm missing something by not using a smaller 
orifice  at higher pressure to entrain air better in my dwwilson Plan 
Two cylinder  forge.

I use .045 MIG tips for orifices and have no trouble reaching  welding 
heat at 20 psi.

The only reply to my question on the  newsgroup was to check Ron Reil's 
website, which is what I'm about to  do now. :)



Don't bother checking there. Everything you can find on that site about MIG  
tips is from me. So why 60 PSI on the English stuff? I can only tell you a  
little story and give you an educated guess.
 
Last year work began on my second book. A large part of the text consists  of 
in depth surveys of brazing tools and supplies. The torch chapter starts with 
 "blue flame" butane torches and works its way right up through all the  
appropriate torch choices for braze work.
Because the English are known both for their brazing tools and for their  use 
of LPG, I sent for a likely looking torch from Bullfinch. Not all their  
torches use four bar regulators, but the biggest one does. Naturally, I had to  
cut their regulator off of the torch hose and replace it with a  0-60 D. O. T. 
cylinder compatible model. This gave me the opportunity  to try their torch at 
the recommended level, and also at lower pressures. The  torch was actually 
much more effective at lower pressures--but it also over  heated. It took a full 
58 PSI to keep the flame from overheating the mixing  tube; at the back of 
that tube is a fairly delicate peizo electric ignition  system.
 
Generally speaking, you will find a perfect orifice diameter per mixing  tube 
size for every venturi burner. If the orifice is too large there will not  be 
enough force generated to entrain sufficient air for total combustion. If the 
 diameter is too small, the burner runs too lean (oxidizing flame) and  is 
difficult to stabilize. However, you can always choke down such a burner,  while 
you cannot do much with the other problem.
 
Also, England and the rest of Europe have just recently started switching  
over from butane to propane. Butane is inherently safer than propane, and also  
inherently feeble in venturi burners. The reason is that butane is only  about 
14 PSI at room temperature. So, high pressure in a fuel gas is  probably a 
bit of a new toy to English engineers, and they are likely to  get carried away 
by the possibilities. Wow, was that snide or  what? Nevertheless, I suspect it 
is more than a little true :-)
Mike P.