Date: Fri, 12 Oct 2001 00:23:49 -0400 (EDT) From: David Scheidt <rufus@brain.mics.net> To: "Gary W. Swearingen" <swear@blarg.net> Cc: freebsd-chat@FreeBSD.ORG Subject: Re: Use of the UNIX Trademark Message-ID: <Pine.BSI.4.20.0110120008040.29248-100000@brain.mics.net> In-Reply-To: <6xzo6xssir.o6x@localhost.localdomain>
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On 11 Oct 2001, Gary W. Swearingen wrote: > Brad Knowles <brad.knowles@skynet.be> writes: > > > I've used such cylinders in Oxyacetylene cutting torches, and > > brazing, but I don't recall them ever being able to generate > > enough heat to do proper welding. > > I think enough heat is not the problem, but things like controllability > and impurities (eg, Oxygen, air) in the weld are the main reason for > using other technologies for common welding tasks. Gas welding takes more skill than most of hte other common forms. It's harder to mechanize, which is a minus in some applications. It's still pretty commonly used. the equipment required is cheap, and can easily be made to weld materials that would b e very expensive to weld with electrical methods. It also doesn't require power, which is a big plus in some places. The same equipment can support welding, cutting, brazing, so ldering and more, which means that if you have reason to want only one set of kit, it's the way to go. > > Also, I'll bet a tank of compressed air is a lot cheaper than one of > either Oxygen or Nitrogen. Anyone know if highly compressed air is > a dangerous fire hazard along the lines of Oxygen (but less so, of > course)? Of course, in the application discussed, it would be reduced > in pressure very near the tank to the normal levels of the tool being > powered. Compressed nitorgten is cheap. the last time I had a cylinder filled, it was something like $20 for a 5 foot toll canister. Compressed air wouldn't be a whole lot less expensive, and you'd have to worry about things like moisture and the ability to suport fire. While compressed air wouold only be about 18% oxygen, that's enough to suppot a fire. > > Also, does anyone know if different gases work better than others > (ignoring dangerousness) because of their different compressibilites? > (I'm not even sure what that means, but I know I can get more power > out of squeezed rubber than squeezed steel.) Well, some gases have different freezing points. A problem with compressed co2 systems is they have a tendency to form dry ice when the gase is released quickly. Nitrogen and oxygen don't do that, but oxygen is a fire hazard. oil will combust spontaniously in the precense of high preessure oxyhgen. Nitrogen is mostly the choice for compressed gas where you don't need some special property. It's relativly inert, it's cheap, theers little or no enviormental impact to releasing it (the atmosphere is abnout 78% N2, after all). > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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