Oxy/Acetylene Cutting torch Questions

[CAROLINA CUMMINS]

howdy,



I've used an oxy/acetylene torch a few times, but never had one until recently. Sorry if these questions sound stupid, but I've never had to set up one from the ground up before. Figured ya'll would know as good as anybody.



I received the torch outfit for Christmas, a Harris(Lincoln Electric) like you can get at Home Depot. A friend works at National Welders Supply, so I bought the tanks and cart off him. I went with the 160 cu ft oxygen and 80 cu ft Acetylene. Should last me a while.



Now, for my questions. The kit came with 3/16"x12. 5 ft hose; well I had to get a longer hose so I bought a 1/4"x25ft hose, is this OK? Any difference in performance or ??? Do I need to go back to 3/16"



And, the hose fittings in the regulators seeped some when I was checking for leaks with soapy water. I tightened them up and the Acetylene quit, but the oxygen still seeps a little. I'd like to stop it completely but not sure what would be acceptable to seal the fitting with? pipe dope? teflon tape?



Flash arrestors? The torch came with check valves on the torch handle, should I put some on the handle; regulators or both??



Thanks,



Steven

 

[formula]

Steven,



The larger diameter hose will be fine. It's a good thing to go up a size when making the hose longer. Makes for less restriction. Only possible drawback is that the hose is heavier and a bit stiffer, but you'll get used to that. On my setup I have a 50ft hose that's 25ft of 3/8" going into 25ft of 1/4".



You should not use any kind of sealant on the hose fittings. They're a ball and socket type of setup that just uses a metal to metal seal. If you've got a leak, don't just tighten it up more. Disconnect the fitting and check both seats to make sure they're clean and don't have any nicks and scratches on them. They should not require much torque to get a good seal.



Flashback arrestors are good, however you must take into account that they produce a drop in pressure that must be compensated for by upping the pressure at the regulator. I have a set of flashback arrestor / check valves on my torch handle only.



As far as the probability of having a flashback... ... . If you operate the torch properly, it'll likely never happen. Also, if your torch mixes the preheat oxy/acetylene in the tip, then that further helps prevent a flashback. What you need to watch out for is to not shove the torch head into an area where the flame shoots back at it or there is a lot of reflected heat. This isn't so much of an issue with a cutting torch, but if you use a rosebud that's a much different story.



Also, to save the life of your torch and make it operate safely you should not run the preheat at anything less than maximum. If you need less preheat, get a smaller cutting tip. The same goes for any tip, such as a welding/brazing tip or a rosebud. Running it too low will cause the flame to burn too close to the tip and overheat it, burn it out prematurely and possibly cause flashback. As an example... . I can run my big rosebud heating tip for several minutes and grab the torch head with my bare hand and it's only slightly hot to the touch.



Happy cutting,

Sean

 

[CAROLINA CUMMINS]

Thanks Sean,



That helped explain alot.



I kinda figured no sealant on the hose to reg/torch handle fittings, but this fitting is the one that threads into the regulator and then the hose threads onto that. It looks to be plain pipe thread. It's not leaking a whole lot, soapy water was the only way I saw it, but I would rather it not leak at all.



As for the flashback arrestors, how much adjustment in pressure is needed?



Thanks, Steven

 

[TowPro]

What was the saying "Ox before Gas and up goes your (butt)

 

[SRadke]

One more thing, NEVER, NEVER, NEVER but any kind of petrolium based product on or near the parts that see high pressure oxygen. Things go "boom". Also, NEVER let the acetylene pressure in the hose get above 15 psi, things go "boom" there as well.



-Scott

 

[CAROLINA CUMMINS]

Thanks for the advice guys,



In my welding course/and book also, the no petroleum based lubricants was highly stressed. We went over alot of safety, but some of the stuff like hoses(size/length) and such weren't went over a whole lot. I guess that's kinda learned by experience.



Thanks



Steven

 

[SRadke]

I didn't catch that you had taken a class, that's good idea. I run across a lot of people who just jump in and they have no idea about the safety. You should be in good shape.

 

[formula]

The only thing that I would use on the pipe threads is teflon tape. Anything else the oxygen could react with and well... ...



When you remove the regulator to hose nipple, check the pipe threads, on the regulator too, to make sure they don't have flat spots or threads ground off from cross threading or whatever. If you need a new nipple, any welding supply shop should have them for a couple of dollars.



As for the pressure drop associated with the flashback arrestors, I don't recall exactly what it is. I think it's something like 2 psi or so. There should be some literature that comes with them which gives you this info.



Sean

 

[KWentling]

Everything I've read and been told is to have arresters at the regulators also (last line of defense). Never heard of the pressure drop through an arrester. Never noticed it if there is one. I own two Victor Journeyman sets and work with numerous sets at work. Good information in this thread.



Kim

 

[formula]

IIRC, the pressure drop is in part flow rate dependent. This page from the Western catalog has some info on flow and pressure drop.....



http://www.westernenterprises.com/enterprises/PDFS/wi25.pdf



Sean

 

[RT66DOC]

Don't forget to close the regulator before you open the tank. Especially the 02. I'm talkin' from experience here, Gents. :-laf

 

[CAROLINA CUMMINS]

Thanks guys,



Yeah, I had to take a welding class which was part of my associates degree. Kinda hard to learn welding in a class with about 15 people in a shop designed for 8. So, we kinda did a lot of cutting outside



This info helped alot, just what I needed. Thanks





Steven

 

[sstefanini]

When I worked off a rig I had 100' of 3/16" hose which would cut 1/2" thick pipe no problem. I like the small hose as its much lighter to work with and roll up.

 

[formula]

As far as cutting tips go, 1/2" is quite small. That's why you can get away with 100 feet of 3/16" hose.



Sean

 

[Vulcan]

Yup arrestors at the torch handle are the way to go. Too bad you did't set your torch up for propane instead of acetylene, its a heck of a lot cheaper.

 

[TowPro]

A lot of my friends who have garages are using Propane instead of Acetylene, There Insurance co's give them a discount if they keep Acetylene out of the building.

Yup arrestors at the torch handle are the way to go. Too bad you did't set your torch up for propane instead of acetylene, its a heck of a lot cheaper.

 

[formula]

yah, propane itself is cheaper. However, it's not necessarily of any advantage or overall cost savings. Propane requires about 3x the volume of oxygen that acetylene does. It has a lower flame temp. The heat of a propane flame is mostly contained in the outer part of the flame. This makes for longer preheats when cutting and piercing. It also means that on thin material you will get more heat distortion due to the longer preheat. Propane is not real good for gas welding and brazing due to the flame characteristics.



Then there's the equipment... . To change to propane, you're going to need all new tips for oxy/propane, a new fuel gas regulator, new hoses (if your hose is for acetylene only) and perhaps a new torch.



It all depends on your application. I'd recommend staying with acetylene. It is certainly the most versatile fuel gas.



Sean

 

[CAROLINA CUMMINS]

I heard about propane being cheaper, but then I also read about it using alot more oxygen.

I don't know how much most places charge for a fill, but I can get them filled for about 24 dollars-80cu ft acetylene and 6. 50-160cu ft Oxygen. That big of tanks will probably last me a while; after I get done playing :-laf



Thanks, Steven

 

[Ol'TrailDog]

Don't forget to close the regulator before you open the tank.

Now maybe we just have a "What we have is is a failure to communicate" :-laf (from Cool Hand Luke for the elders amongst us) But we have just created a bomb (if I may use that word?)



I was taught and always... nay... religiously:



When finished:

1) Close the Acetylene valve. release the Acetylene pressure at the torch/tip. Spin OUT the Actylene regulator so there is no pressure, i. e. spun out. Turn off the Acetylene valve at the torch/tip. Plus I always check to make sure there is no pressure when turning it back on.



2) Next turn off the O2. release the O2 at the torch/tip to flush the torch/tip. Turn off the O2 at the tip. Spin OUT the O2 regulator so there is no pressure.



I've heard of folks cranking up pressure (closing the regulator) unwittingly. The next dude who turns on the Acetylene valve... . oh, surprise... . it was cranked up past 15 psi



pushing up daisies. You never know who has been messing with the tanks, e. g. the next door 7 year old rug monkey.



To start: Not a good idea to stand in front of the gauges peering at the little dials - stand to the side

1) Check the O2 regulator is not closed, i. e. not turned in, and the torch/tip valve is shut. Open the 02 and adjust the pressure. flush the tip with a psst.



2) Check the Acetylene regulator is not closed, i. e. not turned in, and the torch/tip valve is closed (actually you did this when setting the O2 in step 1 out of habit). Open the Acetylene and set the pressure.



3) Set the Acetylene at the tip for the appropriate flame. Then set the O2 at the tip for the intended purpose, cutting, welding, or heating.



Let the "flame" wars begin. :-laf

 

[formula]

OTD,

That's all good procedure. Backing off the regulator set screw is something that so many people don't do, but should be done. Just as you stated, you need to shut off the tank, bleed the line and THEN back off the regulator screw.



Sean