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Date:      Thu, 11 Oct 2001 11:21:53 +0200
From:      Brad Knowles <brad.knowles@skynet.be>
To:        "Ted Mittelstaedt" <tedm@toybox.placo.com>, <cjclark@alum.mit.edu>, "Salvo Bartolotta" <bartequi@neomedia.it>
Cc:        "P. U. (Uli) Kruppa" <root@pukruppa.de>, <freebsd-chat@FreeBSD.ORG>
Subject:   RE: Use of the UNIX Trademark
Message-ID:  <a05101003b7eb12fedac9@[194.78.144.28]>
In-Reply-To: <007701c15216$867d47c0$1401a8c0@tedm.placo.com>
References:  <007701c15216$867d47c0$1401a8c0@tedm.placo.com>

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At 10:35 PM -0700 2001/10/10, Ted Mittelstaedt wrote:

>                                                        So, in the head
>  scratching process of trying to figure out how to answer this, someone
>  happened to look up old actuator patents and ran across one that ran
>  off of compressed air.

	Indeed, that makes a lot of sense.

>                          The patent had of course long since expired
>  but there was enough of a description of how it worked to give them
>  a general idea of what the inventor had been getting at, so they
>  built an actuator that used a cylinder of compressed oxygen (such
>  cylinders are commonly used in welding) that could supply the actuator
>  with mechanical power for a couple hundred cycles.

	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.  When I did welding, I used standard arc 
welding equipment, while my cousin (who is a professional race car 
builder) uses very expensive MIG (Metal-Inert-Gas) and TIG 
(Tungsten-Inert-Gas) welding equipment.

	MIG welding uses a spool of wire that is used as the "welding 
rod" and through which the current is passed, and then that wire is 
surrounded by a high-pressure curtain of inert gas (Nitrogen, I 
think).

	TIG welding uses a Tungsten tip on the welding rod, which 
doesn't itself actually melt.  You have to supply a separate rod that 
is actually melted during the process (kind of like soldering or 
brazing, but at much, much higher temperatures and where the pieces 
you're working on are also brought to a liquid state), but otherwise 
is similar to MIG.


	However, all that said, by far the most dangerous of all 
gases that are used in welding and similar activities is compressed 
Oxygen.  All other flammable gases will have a hard time finding 
enough oxygen to burn cleanly or completely, if they are released by 
accident (such as in an explosion).  However, with enough oxygen 
present, just about anything can be burnt very, very easily.

	I would seriously hope that these people weren't actually 
using compressed oxygen, but perhaps instead compressed Nitrogen, or 
some relatively inert gas.

-- 
Brad Knowles, <brad.knowles@skynet.be>

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