Model Engine Maker

Supporting => Casting => Topic started by: fidlstyks on December 13, 2017, 05:05:28 PM

Title: Using oxygen for an air supply
Post by: fidlstyks on December 13, 2017, 05:05:28 PM
While at the gas engine show at Zolfo Springs Fla I met a man who also made castings. He stated that he used an oxygen bottle for an air supply rather than a blower. I thought this sounded inferior and expensive.
     But I always wondered how it worked. There was a time my blower had quit where I had a full pot of iron melted, but not hot enough to pour. So by the time I got another blower aranged, it had froze up. Most foundry men know that once the iron is cold, it would expand upon reheating, cracking the crucible . So I lost a new crucible.
   So I got this bright idea to try and have a backup air supply. So first I tried using air from my 5 hp compressor . It just did not have the air to even melt aluminum.
   So then I took my torch and arranged it in place of the blower. This I am sure could work, but not as I had it set up. Oxygen is too pure for an old set up. I think if you never used anything else, it would work.
Title: Re: Using oxygen for an air supply
Post by: mcostello on December 13, 2017, 06:36:58 PM
The flame might be too concentrated and intense, might work with fine tuning, might spectacularly be intense. Let Me know Your direction and time and I will look for the glow  in the sky just in case. ;)
Title: Re: Using oxygen for an air supply
Post by: Myrickman on December 14, 2017, 12:18:05 AM
Just thinking out loud but if you had molten iron and inserted an oxygen lance, wouldn't it self heat for a while a la a basic oxygen furnace? Of course it may reduce the carbon content...or make a hideous mess...
Title: Re: Using oxygen for an air supply
Post by: fidlstyks on December 14, 2017, 12:57:41 AM
I was busy earlier and could not finish my writing.
One thing that happened, as I see it , we have all seen the signs "no smoking oxygen in use". They say oxygen does not burn, but it can make a flame of a blade of grass. I burn propane and some times diesel fuel or kerosene . I looked down the blow pipe and it is mildly littered with bits and oily like black, like lamp black from a kerosene light . So what I surmise happened was when I packed my Victor torch handle in the end of the blow pipe where the blower was, and cranked the pressure to 80#  the oxygen made all of those particles burn.It nearly blew my thumb off and was hard on my hearing.
     It did go out and there was a short build up of raw gas first . But I have been doing this since 1980. Something went boom more than ever.
   Look at what it did to the base block. Like dynamite it split it in 3 pieces and cracked the furnace all over. It never blew like that before. It must have filled up more raw gas without burning longer than I thought. But when it blew out the end of the pipe I was sure it the carbon buildup everywhere inside, as it blew out little burning bits and of white fire. Very hot.
   No I am not done till I light the sky up. I am going to make a short blow pipe and make sure that there is no carbon style half burnt fuel in it or on the furnace walls.
    The people at the welding shop always said that if you put oil in your torch and turn up the pressure it will ignite and blow you up. So maybe this is just not a good idea. Was just trying to run it with out electric was my interest . Blowing my furnace apart was a drawback I can deal with. And my hand is only a little sore. And I already do not hear well.
    Around a cupola if the spout freezes up they use a black steel pipe hooked directly to the oxygen regulator and lite it to burning by sticking it in the molten metal. The pipe burns like a torch and cuts through the cold metal.
  Yes I now  think that the oxy would burn out the carbon in the iron.
   I think I will shelve this idea and build a gas engine powered blower .
  Don't look like I can add pictures today.
Title: Re: Using oxygen for an air supply
Post by: crueby on December 14, 2017, 01:06:11 AM
This all sounds like a Mythbusters episode, minus the C4. Just don't play the part of buster!
Title: Re: Using oxygen for an air supply
Post by: Noitoen on December 14, 2017, 07:32:21 AM
I have used mig welding gas mixture and nitrogen as cleaning air supply in electrical cabinets where it was unpractical to take a compressor.
A small cylinder packed with 3000 PSI with a regulator goes a long way.
Title: Re: Using oxygen for an air supply
Post by: John Hill on December 14, 2017, 08:02:37 AM
Take care with oxygen as it can make just about any combustible material into an explosive.  I am certainly too chicken to ever use it except exactly as intended with the proper gear.

John
Title: Re: Using oxygen for an air supply
Post by: Vixen on December 14, 2017, 10:15:33 AM
Take care with oxygen as it can make just about any combustible material into an explosive.  I am certainly too chicken to ever use it except exactly as intended with the proper gear.

John

+1 to that.

Blowing pure oxygen into a hot furnace is NOT a good idea. I hope you do not injure yourself too badly if you decide to continue with your experiments.

Mike
Title: Re: Using oxygen for an air supply
Post by: MJM460 on December 14, 2017, 10:38:03 AM
Hi Fidlstyks,

I am with John and Mike, please don't use oxygen other than the way you are properly trained to do it in welding or other processes where all the safety precautions are in place.  Your gas engine powered blower is a really great idea.

It seems oxygen should be safe, as it is in the air all around us, we breathe it and we use it for medical etc.  But all our ideas are based on the oxygen content of air, around 21%.  The nitrogen that comes with it dilutes it, and gets in the way of oxygen atoms reaching the fuel atoms and so slows the whole process.

How many things can you think of that don't combine with oxygen in rusting or similar.  Most things we think of as flammable need a match or even kindling to get them to light. 

But even 2% enrichment of the oxygen in air changes everything.  Things that don't burn in air, burn when there is more oxygen concentration.  Things that burn, burn more fiercely.  Things that need kindling in air, only need a match, and things that only need a match, only need to have that extra oxygen.  Like those specks of carbon.

With enough oxygen, even the oil in a fingerprint is enough to cause a fire that melts the steel where the fingerprint was, if you are lucky.  Of not, the steel starts to burn!  And the concrete it was standing on.

I was only involved with one oxygen compressor, but it gave me an introduction to the issues.  It had to be assembled and all maintenance had to be done in a special oil free room by workers wearing special gloves, so no fingerprints.  I asked the Manufacturer for a recommendation on fire protection and extinguishers to be provided around the machine. 

The answer was two points.  First, don't be there if it happens.  Second, look out the drawings for the foundations so you can pour new ones while we build a new compressor, there is nothing to clean up first.

Admittedly we were dealing with something near 90% oxygen! But all the standards required some precautions for all concentrations above 2% above the concentration in standard air.  With more precautions required for higher concentrations.  Fortunately we never found out if they were correct in all the detail, but there is no doubt about the first point.

And please don't muck around with oxygen.

MJM460
Title: Re: Using oxygen for an air supply
Post by: Admiral_dk on December 14, 2017, 11:38:20 AM
Back in 1979 I saw some posters of a horrifying accident that happened many decades earlier, in an Oxygen production plant here in Denmark. The blast leveled all buildings in a several square Km. area  :zap:

The cause was a single drop of oil put on a stuck valve, to loosen it  :o
Title: Re: Using oxygen for an air supply
Post by: fidlstyks on December 14, 2017, 01:18:05 PM
When I first posted, my thoughts were to advise people this is a bad idea. Although I am still intrigued by it I do not intend to work at it at this time with out more information. I am concluding now I would need a more scientific apparatus to use oxygen opposed to a blower.
   I think now I also had the air pressure way too high. If one were to use oxy then it would maybe take less pressure or a mixing valve so it comes out mixed, like  a copper tip  not carbon steel, as a welding torch uses copper to cut steel. Since I weld and cut with it, it must scientifically speaking, work.   Or possibly employ the use of nitrogen to calm it down . It may do to just turn down the pressure.  But do to the contamination of combustibles and the voliticity of pure oxygen I would think scientifically if an unregulated mixture entered the furnace it could eventually start burning the carbon in the iron making a huge mess.
  For sure it was a bad idea to put a mere 80# into the blow tube especially with the fire already burning in the furnace.
   
Title: Re: Using oxygen for an air supply
Post by: mcostello on December 14, 2017, 04:39:57 PM
I have heard (not seen) that when the insides of a cutting torch begin burning the flame can eat through and come out the side of the torch. It does not have to use the customary opening. It makes it's own.
Title: Re: Using oxygen for an air supply
Post by: fidlstyks on December 14, 2017, 05:58:53 PM
When the torch starts burning through it is from a buildup of carbon inside. Once it burns just a little bit inside, more carbon builds up from having burned. So the fire makes fuel for itself .
   Interesting how a drop of oil on a valve could be so destructive. A fingerprint burning is even crazier.
  I would think the mixer and tip would need to be back out of and away from the inside of the furnace. Just a blast going through a port.
Title: Re: Using oxygen for an air supply
Post by: Tennessee Whiskey on December 14, 2017, 06:49:41 PM
I remember working with a millwright crew back in the early 80’s and we drilled and tapped a lot of base plates for pumps and motors with a mag based drill. Rapid Tap was the preferred cutting oil and was used in way too much excess. We would have a bit of fun with the new guys by blowing out the chips with a blast of oxygen from a oxy/acetylene torch as a kaboom and flames always followed  :stickpoke:. But I also remember the time one of the guys in the shop capped off one end of a 20’ stick of 6” pipe with a ziplock baggie and the proceeded to fill in the acetylene: when he struck his striker at the open end: 😯 the blast was horrendous, but, because the ziplock held no pressure, it was all concussion  8).

Cletus
Title: Re: Using oxygen for an air supply
Post by: fidlstyks on December 15, 2017, 12:28:01 AM
My neighbor worked in a welding shop. Usually around the 4th of July he would light the torch and set a large welding flame. Then he would snuff it out and dunk the tip in water to cool it. Then fill a balloon .  Then tieing it to 3 more filled with helium and a 20' tail of rag soaked in diesel. He lit it and it would drift out over the ball field and kaboom. Very loud .
    Once they put one in the city sewer and it set it on fire with flames coming out of the grates along the street. Basically it is the same as a carbide cannon.
  I always thought static electricity would set it off. He always was a nut.
Title: Re: Using oxygen for an air supply
Post by: b.lindsey on December 15, 2017, 12:42:06 AM
Which reminds me of those oldie but goodie...

https://www.youtube.com/watch?v=UjPxDOEdsX8

Bill
Title: Re: Using oxygen for an air supply
Post by: Brian Rupnow on December 15, 2017, 01:42:37 AM
My old aunt Minnie suffered badly from emphysema, and was on one of those portable oxygen rigs that have the little transparent hoses discharging just below her nose. When she was about 80 years old I decided I should go and visit my old auntie before she died. It was rather disconcerting--I sat at one end of the couch, she sat at the other. She would pull the little hoses off her face, tuck them away behind her head, and light up a cigarette. After a few good drags and a couple of hacking coughs, she would put out the cigarette and replace the oxygen tubes back under her nose. I did want to see her before she went--She was very good to me when I was a kid. I  just didn't want to go with her in a big ball of flame.
Title: Re: Using oxygen for an air supply
Post by: wgrenning on December 15, 2017, 01:09:28 PM
I have spent as career working at Praxair on All sorts of related equipment including high purity high pressure Oxygen compressors.  Please believe all of the warnings you hear about oxygen.  It may not always be disastrous, but it has the potential to make a catastrophic event.  Many factors, like the concentration of flammable material exposed to the oxygen, its concentration, pressure of the gas, velocity, ect all can have an effect on the reaction.  The main thing to remember with an oxygen "fire" is its violent.  "Fire" is really the wrong word,  Once the reaction starts, the gas spontaneously detonates everything flammable near it until either the fuel ( as mentioned earlier anything made of metal, yes even stainless steel burns quite ) or the gas has been consumed.
.
Think of this real world true experience.  A 10,000 HP Ingersol Rand reciprocating oxygen compressor boosts oxygen in a pipeline from 200 to 300 PSI that feeds a steel mill. A suction screen in the inlet pipeing the he compressor starts to fatigue and a fragment of it goes into the compressor.  It get between the piston and cylinder and get red hot.  This is your ignition.  Within two seconds, the compressor vanishes ( now molten metal) shooting upwards burning holes through the building at 6000 degrees F.  White hot parts of the machine and building land 300 yards away.  The 10" diameter oxygen pipe that used to feed the compressor still has pressure in it from its source and is burning backwards at a several feet a second (like a fuse) spraying mouton steel everywhere.  The whole process usually takes less than a minute, but consumes everything near it.  Pity any living thing in the vicinity.  This is not hyped up or Holywood.   This is just one example of many ( albeit in an industrial setting) real world experiences that have happened.
.
Never Ever Ever us oxygen to accelerate combustion unless in a device designed to do so. Always make sure anything that can come into contact with oxygen is absolutely oil and grease free.  Any never use an oxygen source as a substitution for air.   OK off my soap box
Title: Re: Using oxygen for an air supply
Post by: fidlstyks on December 15, 2017, 01:41:32 PM
Thank you for your input Wayne. I had held off on this attempt for several years because of concerns for safety. I understand now not is the purity of the oxygen causing the problem. I have used oxygen for over 40 years and never seen things burn like it did. But I never turned it up before. We run the liquid tanks with out regulators to cut 12" thick steel when scrapping. But the tanks are low pressure.
   I think theoretically a burner could be designed that would perform but with disaster so close at hand I have abandoned the idea. I believe the man who was melting his iron with it got his plans from the internet. Maybe they forgot to add the warnings.
Title: Re: Using oxygen for an air supply
Post by: mcostello on December 15, 2017, 06:27:39 PM
Worked with a group of mill wrights (1 wrong) who were playing pranks. Someone took a ball baring and put it in a oxygen hose using a greasy glove. When the pranked turned the oxy on the oxy got set off and blew the torch apart in His hand. No injuries some how.
Title: Re: Using oxygen for an air supply
Post by: crueby on December 15, 2017, 06:42:51 PM
Worked with a group of mill wrights (1 wrong) who were playing pranks. Someone took a ball baring and put it in a oxygen hose using a greasy glove. When the pranked turned the oxy on the oxy got set off and blew the torch apart in His hand. No injuries some how.

Prank-ee:  And thats when I threw him into the furnace, your honor...  O:-)

Judge: I understand completely. You are free to go!
Title: Re: Using oxygen for an air supply
Post by: fidlstyks on December 16, 2017, 06:32:01 PM
There are a few types of men I loathe, one is a quiter. So me and my trusty side kick Google who I love searched the web and came up with some new answers. First thing just so no one worries, I am not replacing my set up with pure nor liquid oxygen, which would be what I would use if I perused it. I am staying with the blower
    Just so its clear my first mistake was the way I went about it. When the furnace was about half hot, I just stuck the torch handle in the blow pipe and packed it off with a rag. I was holding it when it went boom, which was something I knew better than to do. It was the end of the day around supper time, so was not thinking.
    So back to my learning . The large steel mills use liquid oxygen. It is all in the burner and mixer . For $38 I can send off for a book that would show me what to do .
    With what I learned I opted to design a tip with a mixer. It would be  basically a large home made rose bud. Placing it in the opening where the blow pipe goes, it will burn and get very hot.
   Without a real need to continue I am going to abandon the use of it for multiple reasons. One costs, one a need to cool the tip, another that I fear I would have to constantly be cleaing the tip. That could mean using multiple tips as an exchange.
   It works but its not for me at this time.  Using propane is not as much trouble as kerosene would be. If I were going to do it,  I would buy a book of diagrams opposed to trial and error.
   Anyway that's how it ends. Back to melting the old way.
SimplePortal 2.3.5 © 2008-2012, SimplePortal