Re: propane instead of acetylene

Posted by TomTex on December 13, 2007 at 06:32:06 from (12.74.214.20):

In Reply to: propane instead of acetylene posted by n8terry on December 12, 2007 at 15:17:06:

I have cut and pasted the following for you guys. Tom

I'm looking at Northern Tools Generico torch and tank kit with a 20# O2 tank and a 10# acetylene tank and I have a question: how often will I be running back to get the tanks re-filled if I'm doing some cutting of 3/8-1/2 mild steel and maybe heating up stuck nuts?? I know I won't use it enough to lease the tanks. I appreciate any feedback and Happy Memorial Day!" Steve in CT

"A couple things on this one.
First, most all Generico stuff is interchangeable with Victor, from tips to valve seats and regulator diaphragms. I've been using Generico regulators for about 7 or 8 years now on a daily basis with no problems yet.
I don't like acetylene very much and prefer to use LP for 99% of everything I do. If you are wanting to use LP, you need to know a few things. First, you must use type "T" hoses with LP. The normal hoses used with acetylene will become soft and blow out after time exposure to LP gas. Anchor brand hoses are cheap and to be honest with you, they are the best I have ever used, remaining pliable in extreme cold is their biggest plus for me.
Next, you need a torch specifically designed for use with LP or it will not work properly. The Harris type "F" is designed for use only with LP/MAPP (MethylAcetylene-ProPadiene) gas and is the only one I have found that will mix the LP/O2 to give a proper burn at the tip. One of these will run you about $140 with a #2 cutting tip. The best part of the Harris design is that the rose bud tips screw right onto the cutting torch tip threads so there is no changing handles.
Using LP takes some getting used to because setting the flame for different uses is slightly different from that of acet. For cutting, you need to use an oxidizing flame (very short light blue pre heat cone). LP cuts much faster, thicker and cleaner than acet once you have the proper torch/tip combo and get the feel of how to set it. One of the biggest plus sides to using LP is that you don't get the popping and blow backs when cutting dirty/rusty steel like acet does.
LP does require slightly more O2 than does acet but the end result is that you get much more cutting power for the same amount of O2 as with acet. fuel gas. LP is also much safer too. Acet can self ignite when in gas form in the hoses/regulator if the gas pressure gets over 21 psi, LP will not even if the line gets full bottle pressure because of a regulator failure or operator error.
The myth that LP takes longer to pre heat or start cutting comes from those people who either used the wrong torch or the wrong flame setting. Too much gas at the tip will cause you to have a cold pre heat flame. Too much O2 will cause a cold flame and make the cutting very slow and sloppy. In most cases of guys complaining about LP not being as good as acet comes from them trying to use equipment that is not designed for LP use. The Victor and Smith adapter tips for use with LP on a torch handle designed for use with acet will not produce a proper LP/O2 mix and the flame and performance will suffer greatly. Properly set, I can hold a cut with LP on my Harris torch 2" to 6" from the work piece where with acet, you will loose the cut when the tip gets 1/4" or more from the work piece.
The kerf of the cut from LP is also much easier to clean especially when cutting rusty steel. In most cases, I can cut heavy thick rusted steel with LP and do all the cleaning easily an quickly with a chipping hammer. Grinding is rarely ever required even if MIG welding the steel with solid wire. When done properly, the cuts from LP are confused with those made by plasma cutters.
For all the heavy duty cutting I do, I have yet to need a LP tip bigger than #2 and as a matter of fact, I don't even own any other size tips for it except for the rose buds. Adjusting the O2 pressure will control the thickness of the steel you cut while maintaining the same pre heat flame size and setting. I have made cuts on steel 10" thick that were clean and smooth with a standard #2 cutting tip but using 80 to 90 psi of O2 pressure. Yes, you do use more O2 but you are not using any more fuel gas for the heavier cutting as you need to do with acet. You save time because you don't need to constantly change tip sizes for changing material thicknesses. I rarely change O2 pressure settings because the cut valve on the Harris torches allows you to feather the O2 cutting pressure at the handle. This takes some practice but is a real time saver once mastered.
Now as for the tanks. A 20 pound LP tank will last for about 20-30 of the biggest O2 tanks known as the 292 size (the ones that are 10" in diameter and stand 5' high). A 3 or 5 pound LP tank is sufficient for any DIY'er uses unless you are running a large rose bud tip for long periods of time. You can buy the medium sized O2 tanks from most any gas supplier for about $150. What you need to ask BEFORE you buy:
1- will they exchange the empty for a full one or only fill your tank?
2- If they will only fill your tank, how long is the turn around time (time you wait to get the tank back)?
3- Are they going to charge you for the hydro test on the tank when it comes due (most run about $35)?
Just FYI, most gas suppliers will exchange your tank if purchased from them and not charge for hydro testing and will offer you a transfer or buy back option if you move from their service area because some suppliers will confiscate tanks that are not branded with their name while other don't care or will do a dealer swap. You don't want to shell out $150 for a tank, move away from the area only to have to purchase another tank at the new location.
Some words of advice. Don't slack on price and size of the equipment. Get yourself a 16" Harris torch, the big heavy duty two stage Generico regulators, Anchor brand type "T" 50' twin hoses in 1/4" ID diameter and either Harris, Goss or NTT LP tips. If you decide to go with acetylene, get the heavy duty two stage regulators, 1/4" ID twin hoses and the Generico acet torches are fine with either Generico or Victor tips. Don't limit yourself to smaller hoses or a light duty torch because you will regret it down the road. The cost difference between going heavy duty and light duty for the entire set-up will be less than $100 and well worth the extra start up cost when you do not become limited by the size of the equipment.
As for me, the only things I use acet for is flame spray build-up using powdered metals and some very special cast iron welding where I need to add carbon in order to get a proper weld process. I brass and silver braze, solder and cut with the same #2 cutting tip. It takes time to get used to it and learning how to set the flame and gas pressures to get the tip to do what you want but once the learning curve is over, you save more time than you can imagine and don't need to have pile of specialized equipment to get the same type and amount of work done. If you have any specific questions, feel free to email me directly." Mark Kw

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