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Cadmandu

Need Help Acetylene Tank Pressure problem

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Hi All

I just bought a torch set from Lowes took the tanks down to get them filled and they took my new one and gave me an old one tha was filled. The threads were banged up and needed dressed with a thread file. The problem is the fuel tank has a 3/16" square valve that you open and close with a tool that came with my kit. I threaded the gauges on the tank and made sure that the regulator valve was backed out and the valves were closed on the torch handle. I then opened the tank valve 1 full turn and the gauge on the right measured 150 psi. After attaching all the gauges and hoses to both tanks I did some brazing when finished I turned off all the tanks backed out both regulator knobs then bleed the hoses. Here is the issue, I read 180 psi on my fuel tank gauge even though the 3/16" valve is closed tight. My regulator knob is backed out and no pressure in the hose. The oxygen tank when turned off both gauged read zero. Is this a problem?

Thanks Dan

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sounds like you have pressure trapped between the tank shutoff and the regulator, try opening the regulator and valve on the torch but leave the tank valve closed.

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When you say open the regulator do you mean turn the knob CW so I could read pressure on the left side gauge then open the torch?

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yes that should drain off the pressure. when I shut down torches I always shut off the tank then drain off the pressure then back the regulator out.

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Thanks so much I will go down stairs and do that. When I set the gas and oxy what should each gauge read for brazing or filler rod welding. I did a pretty bad job today.

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Worked in HVAC and also played with torches for many years (30+/-). In those years have gotten many of tanks with messed up threads  , even empty ones  :ranting: . In my years of hauling tanks around in the van and the tanks in the shop I never bled my hoses or backed off regulators . I always shut tanks off and made sure touch valves were firmly closed . To me it's just wasting gas bleeding hoses and adjusting regs , every time you go to use them . :twocents-02cents:  Ok let me here it from the safety patrol .

Edited by ACman
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I ran between 13–15psi on oxygen and 5-7psi on acetylene for brazing . 

Edited by ACman
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Thanks AC man is it the same for filler rod welding? What is a carburizing flame and when do u use it?

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it only took one time of having a bad regulator blowing up for me to start bleeding off the lines and gauges, what little bit of gas it uses doesn't make up for the safety end of it.

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1 hour ago, ACman said:

 

I ran between 13–15psi on oxygen and 5-7psi on acetylene for brazing

 

Sounds right - couple of safety tips: I didn't see a check valve on your acetylene tank ( maybe I missed it - I have a very old outfit )  - you really do need one to keep from backfeeding any flame to the tank...also, only turn your acetylene tank valve open enough to get your 5 to 8 psi on the gauge..this is so you can shut the flow off quickly in the event of a problem - give the oxy tank a full turn or so..

 

3 hours ago, Cadmandu said:

150 psi

If that is the oxy tank ( you said the tank on the right ) it should read maybe 1500  to 2000 when full...then 15 at the torch end for brazing and around 30 to 40 psi for cutting.....acetylene tank should read 175 to 225 psi with a full tank...for cutting I use 8 psi for acety and 30 psi for oxy..for 1/4 to 3/8 inch metal..:)

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Man , haven't done any filler rod welding since high school and that was a long time ago. Check out weld guru.com lots of good info there. 

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Well Benji and all. I opened the fuel valve and bleed the gauges and hose last night. Went down stairs this morning and back up to 190 psi. I was told to use a coat hanger i think i used a thin stick of ss rod I assumed it was steel. Will go to Guru thanks I have alot to learn.

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I own a machine shop, and have welded, brazed, and soldered about everything imaginable. After almost 40 years, have yet to blow myself up due to not bleeding the lines. Too, in all the shops I have worked in, not one ever bled the lines on a torch set, they only made sure the valves were closed tightly.

 

The valves on acetylene and oxygen tanks from firms such as Airgas, Linde, Indiana Oxygen, and all the other big names, are the finest made, and are designed for extremely long life. They are made to be opened and shut repeatedly for literally decades. Their quality is the same as the tanks themselves. The oxygen tanks are designed to safely store at pressures well over 3000 PSI, although in practice I have rarely seen one filled to over 2800. The oxygen tanks are required by law to be "hydrostat tested" to ensure they have not weakened every few years. The pressure at which they are tested is about twice thew working pressure if I recall correctly. Every time a tank is tested, the date of the test is stamped into the tank just below the valve. To give an idea of how strong these tanks are, I have just recently gotten oxygen tanks that have dates on them that go all the way back to 1947. The above said, one will occasionally find a tank with a bleeding valve. If such is the case, take it back to the supplier for an exchange.

 

The regulators are not so robust. Even with a high quality set such as Smith, Victor, or Harris, they are made to be adjusted only when different pressures are needed for a given job. When done with the torch set, lightly turn off the mixer valves (the ones on the torch handle), with the oxygen being shut off first (prevents popping and blow back). And I mean lightly seating the valves. Mixer valves are similar to the needle valves on a carburetor, and can be damaged by over tightening. Then firmly close the tank valves.

 

Jerry is correct regarding the approximate pressures for different torch jobs. The only difference is that I normally leave my oxygen regulator at around 35 to 40 PSI, and just adjust the oxy. flow at the mixer for welding and brazing.

 

When doing any welding or brazing, you really need some sort of "flux" to clean the metal as you apply the filler. In brazing (brass/copper alloy), you can purchase some specially prepared compound from your local welding shop, or you can save your money and buy a container of 20 Mule Team Borax soap. It is all the same stuff. Borax is the ingredient that does the cleaning. If you go the detergent route, make sure there isn't a bunch of additives. I buy the borax labeled as a laundry supplement, the stuff you add to your regular detergent to aid in cleaning, as about the only additive is a scent. To apply to the area, you heat the area to be brazed and sprinkle a bit of borax there, or you can heat your brass rod to a dull red, then dip it into the powder. When you heat the brass to melting, you will see the borax turn to a clear liquid and spread all about the joint, carrying away impurities as does. Dirty metal may require larger amounts of flux.

 

Regarding welding steel, you can use coat hanger wire. A coat hanger is a mild steel very much like the steel used on mower decks, seat pans, frames, mule drives, etc. Shafting used in these tractors, along with mower blades are an alloy steel that contains other metals such as molybdenum, chromium, etc., and higher levels of carbon. You really don't want to use a hanger on these parts, and likely don't want to weld them anyway.

 

If welding mild steel, you will also want to flux the weld area, but you need a higher temperature flux, as borax will not work very well. In this case you need to get the flux from your welding supplier or online. Look for something labeled FerroFlux, or similar. Make sure it is listed as being suitable for welding steel. In appearance, it will be a powder, but unlike borax which is white, a ferrous (iron-based) flux will have a reddish appearance. As a side note, a ferrous flux is also used to weld cast iron when using the oxy-acetylene method, and using cast iron rod. I will not go into welding cast iron, as it requires several added steps, and requires a high level of skill and experience, not to mention time.

 

On the flame itself, there are essentially three types. They are carburizing/reducing, oxidizing, and neutral. Carburizing means you have more acetylene in the mix, neutral is a balanced mixture between the oxygen and acetylene, and oxidizing has a larger amount of oxygen. In most cases, you will use a neutral flame. Carburizing is employed when working with cast iron, and other applications, and a slight oxidizing flame can be used with brazing. I suggest looking up the numerous articles on flame types that can be found on the Web. They will describe what their uses are, and the actual appearance of the flame itself.

 

Lastly, as I am getting tired of typing and have chores to do, I will add a couple things about the tank valves. As has already been said, you open the acetylene tank valve no more than a single turn, a half turn or so will usually suffice. Only enough to make sure you have sufficient flow and pressure when welding/cutting. The oxygen valve can be opened all the way.

 

When you have gotten new tanks, before installing your regulators you absolutely have to clear any dirt from the internal threads and valves on the tanks first. You do this by "cracking" the valves before you screw on the regulator. After your tanks are securely mounted and chained/strapped to the cart, you briefly open each valve approximately 3/4 turn, then quickly close. The outflow of high pressure gas will blow out any dust and dirt from the opening. Make sure you are not standing in front of the opened valve unless you want to be injected with said dirt, or get a face full of smelly acetylene.

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@jdleach you took the words right out of my mouth . It took years of practice to learn the art of brazing and soldering . Learning how much heat and when to add your medium ( Silver solder , soft solder , flux covered brass , ect. ) just takes practice . Believe me you'll mess some things up along the way , but when you learn to fix your mistakes is gratifying . Practice , practice , practice . Maybe look into a welding class at your local college or trade school . I surly believe schools should bring back shop classes and teach these kids real hands on experience , it really helped me out growing up .

Edited by ACman
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Hi All,

This is great info I have been documenting all of this. Thanks JD for sharing and taking the time to say so much. I took my tank back yesterday and it was leaking, so they gave me another one.

I want to buy a good text book like a Vo tech type in color that covers OFW well, any suggestions. What flux do I need for mower deck repair and can I use a coat hanger?

I ordered two flashback arrestors for the regulators can I take out the check valves now in the torch handle. I was told if you use both I will have a lot of restriction.

Thanks Dan

 

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Dan, as I wrote in my too long post above, you need a special flux for welding steel and iron. Used to be able to get Ferro Flux, but that appears to now be unavailable. The stuff you want is called "anti-borax".  There are several makers on the web that sell it, one being Superior. Be aware that you don't want to breathe the fumes for an extended period, as there are health risks. However, in a well ventilated area, and not welding for hours and days on end, you should be OK. Personally, I have welded with it for years, and have suffered no ill effects. No risks like cancer, but the stuff has been known to cause lung and skin irritation.

 

Coat hanger will work fine, just scrape off the shellac, or whatever coating it may have on it.

 

I would ditch the check valves. If you want to ensure you don't have flash/blow backs, ALWAYS turn the oxygen off on the mixer FIRST, then the acetylene.

 

One MAJOR caution I forgot to include in my first post.

 

KEEP OIL ABSOLUTELY AWAY FROM THE OXYGEN TANK VALVE AND REGULATOR!!!!! 

 

Make sure your paws are not an oily mess when changing out your oxygen tank, and never let oil get near your regulator. If you somehow allow any type of oil to enter into the oxygen tank valve or regulator, you run a quite high risk of blowing the regulator up. The reason that this can happen is due to the "diesel effect". As you are aware, diesels operate without spark plugs because it was discovered that if you compress a liquid fuel (kerosene, oil) combined with air to a certain point, it will ignite on its own. The same thing can happen in your regulator. A minute amount of oil inside your valve or regulator can almost instantaneously heat to ignition when hit by 2500 PSI of pure oxygen. The results ain't pretty. It is rare that such an event happens in industry, as most folks who work with compressed air and oxygen are aware of the potential danger. It does happen occasionally though to persons who are unfamiliar with the risks, such as novice welders, backyard and basement mechanics and tinkerers, and scuba divers. Yup, divers. Many are not up on the diesel effect, and will carelessly stow or transport their gear, allowing oil to contaminate the tank valves and regulators.

 

Do yourself a favor and read up on torch welding, and familiarize yourself on the dangers. While there are risks with using such an apparatus, they are great tools that can be used safely when operated intelligently. 

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Thanks JD, The oil update was really surprising. Are you saying to put the flashback arrestors up by the regulators and remove the check valves. Do the flashbacks do the same thing? The only reason I asked about the flux again was because when I returned the leaky fuel tank I could not find the ferro flux in the store so I was hoping to get another source. Thanks for the info on the coat hanger varnish. I have learned alot here in this post, great forum and great guys. I am taking a welding course in Jan at the local Vo-Tech for 200.00 I get 24 hrs of class room and hands on. What size tip do I need for deck repair of brackets and sheetmetal repair?

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In all my years of using a torch set, I have never had arrestors or check valves on the sets I have operated. That said, I see the benefit. Whenever you have blow back, evidenced by a loud pop or bang accompanied by the extinguishing of the flame, hot partially unburned gas travels backwards through the tip and into the mixer. Although I have never seen it, I suppose if it is bad enough, it could travel all the way to the regulator. What check valves and arrestors do, is stop those sparks and gases at some intervening point. Makes the set safer, but in my mind performs a more useful function. That is to keep the carbon residue a blow back leaves from encrusting the innards of the passage ways. As for the difference between an arrestor and a check valve, I am not sure, but suspect they perform the same basic function, which is to prevent or limit gases from traveling the wrong direction in your torch passages.

 

While you can have flash back from holding your tip too close to the work, one of the biggest reasons is improper order in shutting off the flame. Again, turn the oxygen off first, then the acetylene.

 

As for the placement of the arrestors, follow the directions of the manufacturer, or ask your local welding jobber. My feeling is that whether you use the arrestors, or the check valves, I would want them as close to the mixer as possible. Since I have never used them, I just don't have the experience to say where the best position is.

 

The flux you want is Anti-Borax #1, and is made by Superior. This stuff has been around for decades and works well. My shop was opened in 1946 by my grandfather and his partner, and over the years we used both Anti-Borax and Ferro Flux products. On the welding shelf I still have a can of Anti-Borax that is probably 40 years old (we would buy several cans at a time). Still has about 1/3 of a can of flux in it, but quit using it as mice got into the shop and pissed in the can. Flux still works, but I can't stand the smell of burning rodent pee. Got another can. 

 

At any rate, the flux sold today is the self-same stuff, down to the antiquated labeling. I would get a can from these guys online:

http://shop.atlaswelding.net/

 

You may find the flux cheaper elsewhere if you want to look, but a little less than $9 a 1 lb. can sounds reasonable to me. I wish I could tell you to just go to your local welding supply, but you very likely will find they don't carry it. Columbus, Indiana is a very industrial city with a lot of shops and factories. Have several welding suppliers, but none carry Anti-Borax anymore. Not many folks left who know how to actually weld (not braze or solder) with acetylene, so it doesn't pay for them to keep it in stock. 

 

As for the tip, I would start with a medium sized one if you welding on the deck. the thin sheet metal found in the fender pan and hood will require one of the smaller sizes. If I remember correctly, most welding sets include either four or six tips. Pick one from the middle of the pack for the deck metal. I have long forgotten the tip sizes, and just select the one I need by the size of the hole. 

 

Another bit of advice. Although it is a little late, since you have already purchased your set, I suggest in the future that you limit any purchases of tips, mixers, regulators, and other hardware to one of the long time makers of welding equipment. The "big three" are Smith, Victor, and Harris. The first two firms are American, and Harris is Canadian. All three make fine products that will literally last you a lifetime. Victor and Harris may make or sell some cheaper models, and I would shy away from those, but overall, you cannot go wrong with them. The king, hell the emperor of torch outfits is Smith. Their top-line regulators and mixers are chrome plated, and beautifully manufactured components. Almost a work of art, and something you rarely see anymore. Of course the price reflects that high level of quality, but they are well worth the cost. I would look closely at the set you bought. It may very well have been made by Victor or Harris, and sold under another name. Try to find out who the real manufacturer is. Once you have determined who it is, and say it is Victor, you can then buy Victor tips and other parts, as they will likely interchange.

Edited by jdleach
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:text-goodpost: Guys ...being an HVAC dude like @ACman I am a brazing fan and do most of my repairs with off the shelf pre fluxed brazing rods. Thanks for the looog posts @jdleach learned a few things! :handgestures-thumbupright:

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Thank you very much for the compliment Jim, but I ain't no Guru. Just picked up from my grandfather and father a few things about welding, then tried to round out my knowledge with a lot of years of experience. Made a boatload of mistakes along way, but learned from them.

 

We used to use the pre-fluxed rods at the Shop, but gave them up. Cost was part of it, as they are more expensive, but the big thing was that they were constantly shedding the coating if they sat on the shelf for a long period of time (as can happen in a non-climate controlled environment. Changes in temperature and humidity would cause the flux to peel and flake away.), or the coating would get banged off. They are convenient though, as you don't have to have a can of borax powder beside you to knock over and spill (or rodents to piss in).

 

At one time, I used to read everything I could lay my hands on about torches and their uses. Things like "wrinkle bending" tubing, cutting cast iron with a cutting torch (it can be done, but not easily), how to actually WELD cast iron, and the differences between true welding, and some form of solder/brazing.

 

That last above is really interesting. Most skilled welders today do not know the difference between true welding, and some type of brazing. In a nutshell, true welding is when you apply the same, or similar type of filler rod to the puddle, and the filler and base metal actually mix to form a single mass. In brazing/soldering, the filler rod does NOT mix with the base metal, just simply adheres to it, much like a glue. Tin/lead and silver solder works this way, along with the various forms of copper/brass brazing.

 

Welding cast iron, true welding, involves the use of gray cast iron filler rod, not some nickel alloy. You mention to most welders that when they weld iron with a stick welder that they are not really welding, they will think you are a fool. Truth is, the only way I know to truly weld cast, is to use a torch set with gray-iron rod. Whenever you use an electric arc to weld cast iron, you can bet your sweet bippy the filler is a nickel alloy.

 

In arc welding cast, the nickel is deposited and acts in much the same way as brass in brazing. It bonds to the base metal, but does not actually mix. This whole bonding thing has to do with properties certain metals possess. The property we are concerned with is "affinity", or the ability of one metal to adhere to a dissimilar one. Brass has an affinity for iron-based metals, and so adheres to them at the correct temperatures. Lead/tin/zinc works that way especially well with copper-based alloys, although it also like ferrous-based as well.

 

Nickel likes cast iron. But nickel isn't cast iron, so you are not "welding" with it. If you were to cut through a cross section of cast that had been welded with nickel rod, you will see a clear demarcation, or line separating the nickel weld and base cast iron.

 

If you really want to hone your welding skills, try welding cast iron with gray cast rod. Damned difficult to do, but if done properly, when you are finished your part will not crack all to hell, and when you grind the weld flush to the part, you will not be able to tell where the weld begins, and the base metal ends.

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Just bought a pound of Anti Borax #1 15.00 shipped. You are a real expert and I feel very blessed to read your post.

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Thank you for posting Michael. Praxair is my jobber now, and has been great so far.

 

Used to use Indiana Oxygen exclusively for the family machine shop from the 1940s up until the mid-1990s. Around 1995 or so, IO began a policy of making all their customers prove they owned their cylinders. I remember taking my argon and CO2 cylinders down one day for exchange, and having the counter guy say I had to produce the receipt from when we initially bought the tanks. The guy knew me, my father, and my grandfather as well, so was familiar with our business. Told him that we bought the MIG cylinders sometime in the 50s, and I was sure we no longer had the receipt. Was told that if I could not produce said receipt, the cylinders would be seized, or I had to buy them again. Ask them to check their own files to find the records, and that request was refused.

 

Needless to say, I never unloaded those two tanks, told them where to stuff it, and have never been back. Still have those cylinders. I figure I will eventually cut them up for scrap. Indiana Oxygen will certainly not be allowed to steal them from me.

 

On another note. Since you work in the welding industry Michael, if you find any of the information I have posted to be in error, please do not hesitate to correct me. I don't weld as much as I used to, and some things are getting a bit foggy with time. I absolutely do not wish to steer anyone wrong.

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2 hours ago, jdleach said:

another note. Since you work in the welding industry Michael, if you find any of the information I have posted to be in error, please do not hesitate to correct me. I don't weld as much as I used to, and some things are getting a bit foggy with time. I absolutely do not wish to steer anyone wrong.

I'd say you pretty hit every point correctly so far  :chores-chopwood:! ... It's like high school all over again.:) Had the best teacher ever, he even taught my two older bothers and my song or three . Pretty munched forced to to retire aftrer 34 yrs . He was only in his 50's looked 35 . Walking talking Encyclopedia in all subjects . That's the type of teacher every kid needs.

 

@WHX8 I'd didn't use flux covered rods or any flux for that matter. :scratchead:Silver soldier 15% . 

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I meant for fixing :wh: thats what I use Jeff...yah on the money job 15% & nitrogen purge. 

I hear ya on the cylinder thing Jd....had a similar situation. ....where the sun don't shine.

Edited by WHX8
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