Portable O/A torch question

I recently pulled out my portable Victor O/A torch after several years and went to the welding supply store for some new bottles. When I got home, I couldn't hook up the new acetylene bottle because it had damaged threads. I took just the bottle back to the store and exchanged it, but on the way home it tipped over. Before hooking it up, I cracked the valve to blow out any dust and attached the regulator. I opened the tank valve and then when I tried to open the regulator valve, the regulator made these weird puff-puff-puff noises and the low pressure needle jumped up and down. I then shut everything down and purged the system. I asked around and it was suggested to me that it was probably the acetone. Is this a problem that will sort itself out as the acetone settles back down, or do I now need to have the regulator serviced?

Also, I am a little rusty, so I would like to ask if I have the proper start-up/shut-down procedure. Step one, make sure that the regulator valves are closed. Step two, open the O2 all the way and open the C2H2 about 1/4 turn. Step three, open the acetylene valve on the torch about 1/2 turn and open the regulator valve until the low pressure needle reads 3-5 psi (I want to cut 1/8" and 1/4" mild steel) and then close the acetylene valve on the torch. Step 4, open the O2 valve on the torch body all the way and open the O2 valve on the cutting attachment about 1/2 turn. Step 5, open the O2 valve on the regulator until the pressure is about 20 psi with the O2 lever depressed and close the valve on the cutting torch. Step 6, open the C2H2 valve about 1/4 turn and light the torch. Step 7, open the O2 valve on the cutting torch until the flame is neutral.

Shut down: Step one, close the O2 valve, followed by the C2H2 valve. Step 2, close both tank valves. Step 3, open the C2H2 valve about 1/2 and release the gas until the low pressure needle drops to 0 psi. Step 4, close the C2H2 regulator valve followed by the C2H2 torch valve. Step

5, open the O2 valve on the cutting attachment about 1/2 turn until the O2 pressure drops to 0 psi. Step 6, close the regulator valve, followed by the valve on the torch body and then the valve on the cutting attachment.

Is that correct?

Thanks for your help, Rob Dennett

Reply to
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Here are the written notes that go with Ernie's gas welding class. Enjoy - GWE

Oxy-fuel welding/heating/cutting/soldering/brazing class



Acetylene cylinder is low pressure, light wall construction, filled with plaster saturated with acetone, acetylene is dissolved into the acetone. Analogous to soda water, when bottle cap is removed, gas bubbles out steadily for a long time until finally exhausted. Dissolved acetylene is stable, safe, gaseous acetylene is very unstable and explosive and DANGEROUS. There is a maximum rate of acetylene withdrawal which must not be exceeded, often cited at 1/7 the tank capacity. For example, a tank holding 330 cubic feet has a maximum withdrawal rate of 47 cubic feet per minute. Attempting to withdraw acetylene in excess of this rate will draw acetone along with the acetylene, with nasty effects like large pops. An acetylene tank approaching empty can be detected by little green flashes in the flame; this indicates tiny amounts of acetone being drawn out and the tank should be taken out of service and refilled. letter designations MC originally used to fuel motorcycle headlamps B originally used to fuel bus headlamps (acetylene headlamps) Oxygen cylinder is high pressure, just gas, very heavy wall construction. two kinds of cylinders, industrial or medical same gas, medical cylinders cleaned to much higher standards cylinders are never mixed; mixing cylinders can lead to huge fines other LP gases LP means liquid petroleum, and includes propane, chemtane, MAPP, flameall and also propylene and propadiene; all basically sexed up propane. All LP gases come in low pressure cylinders like propane, and in fact you can swap propane 25 gallon (aka "100 pound") propane cylinders for Chemtane cylinders at Central Welding. Chemtane is a little more expensive than propane, much cheaper than acetylene.

"Rental" cylinders and "Ownership" cylinders are 2 completely separate entities. Rental cylinders will have a welding supplier's name imprinted or embossed on the "Head-Stamp Ring" on top of the cylinder. These cylinders can NEVER be owned, ever ever ever. If you buy one used and try to have it filled, it will be seized by the supplier and returned to the supplier on the head-stamp. Many of the less expensive cylinders seen on craigslist are actually rental cylinders, although the seller often denies this. A useful strategy is to program the number of a local welding supply into your cellphone before you go look at a set of cylinders. If there is any writing on the neck ring, call the welding supply while you are standing in front of the cylinders. Many sellers have a remarkable change in attitude when you look up at them and inform them that the welding supply wants to know where they live so they can call the sheriff. When you do get owner cylinders and swap them for full ones, save the receipt from the welding supply. When it comes time to sell the cylinders such receipts end all discussion about owner/rental.

Ownership cylinders can have a blank Head-stamp ring, a military head-stamp (USN, USAF), a school head-stamp (Univ. Wash., South Seattle Comm, Coll.) or a private company head-stamp (Boeing, Caterpillar). With ownership cylinders, you don't necessarily own THAT CYLINDER, but rather A cylinder OF THAT SIZE. You simply swap your empty cylinder for a full one, the same size, at the supplier, and pay for the gas.

All cylinders must be hydro-tested every 7 years. If you buy used ownership tanks that are out of date, you will have to pay for a hydro-test before a supplier will accept them. The supplier will send them out and charge you for the test. If the cylinder passes they simply give you credit for a tank of the same size, and you pay for the gas. You can request the same tank, but you will have to wait for it to be sent out, filled and returned. Usually 2-3 weeks. Tanks have not changed for over 70 years. You will occasionally find high pressure cylinders in the US with German Swastikas on them. These were seized military tanks from WWII, and will be around for a long time since they were built more heavily than most cylinders.

All fuel gas cylinders have left-hand threads except A, B and MC acetylene tanks. A, B and MC cylinders are a holdover from the old days when they were used to power Automobile, Bus and MotorCycle headlights.

MC tanks are the smallest acetylene tanks used, and are popular with jewelers and plumbers. B tanks are one step up and are popular with jewelers and hobbiests. A tanks are very rare, and are in-between B and MC in size.

Welding Cylinder Data (cap. in cubic feet)

Oxygen Tank Designator Capacity Height Dia. K 251 51" 9" S 156 46" 7 3/8" M 125 47" 7" Q 92 30" 7 1/8"

Acetylene Tank Designator Capacity Height Dia. #5 350 45" 12" #4 150 38" 8" #3 75 29" 7"

Fuel gases:

Acetylene: made from dripping water on calcium carbide, acetylene used to be user- generated for everything from toy "carbide cannons" to household gas installations which had an acetylene generator in an outbuilding, generally a blockhouse about 100 feet from the main home with 3 walls made of concrete blocks and the 4th wall (the one that faced away from the house) made of wood so that if the acetylene exploded, the wood wall would fail and the blast energy would be directed away from the home. Acetylene generators were also used in industry and are still around as quaint period pieces, but insurance practices now dictate that acetylene production all be done in large plants. The welding gas industry would love to see acetylene go away entirely because of the astronomical insurance costs associated with handling it, but it is necessary for welding as no other gas has its attributes of heat without excessive amounts of elemental hydrogen being introduced into the weld metal.

very expensive fuel only fuel gas appropriate for welding steel

Propane/Chemtane/MAPP/Propylene/Flameall: (LP gasses) not suitable for welding, best choice for heating or cutting use same regulator as acetylene propane is a much cheaper gas than acetylene


some tips on looking for quality inspect end of key inexpensive regulators have flat tip good regulators have cone tip next step up is the best general quality found - a ball bearing swaged into end of key. some high end regulators have tip shaped to fit between 3 ball bearings large diameter diaphragm -> more precision control Victor, Airco, Smith regulators are good brands old Union Carbide regulators are "Rolls Royce", but very heavy It often makes sense to buy high quality older 2-stage regulators and pay to have them rebuilt (Seattle has an excellent torch repair vendor; Hansen & Miller in Ballard) as this can be about as expensive as buying medium- quality regulators new and can give much better quality.

Single Stage regulators slowly decrease their output pressure as the tank pressure declines.

Double Stage regulators adjust for the dropping tank pressure to maintain a constant output pressure.

Single stage regulators cost less to buy and repair.

On high pressure cylinders always crack the valve slowly, doing it fast breaks down regulator seats. If a regulator is leaking out the overpressure valve it usually means the seats have been damaged.

Some inexpensive (Harbor Freight) regulators, the diaphragms aren't finished cleanly so they stick. This leads to pulsing of the pressure so you will see instability in the flame cone. It can make these difficult to work with.

Both acetylene and propane cylinders use a CGA 510 connector (aka a POL fitting) so you can generally use an acetylene regulator on a propane tanks but most acetylene regulators are set up for the range 2-15 psi so if you plan to use more propane than that you should either get your acetylene regulator modified to use a stronger spring and different gauge or you should use a regulator set up for propane. In addition, once you use a regulator for propane (which leaves tarry residue inside) you should not go back to acetylene with that regulator, as the acetylene gas can react with the tars and this is dangerous. (This last according to Victor customer support.)


Smith Nickel plated, excellent welding torches, straight cutting torches have a strange feel to them. Fuel is mixed in cutting tip. High quality gear, very expensive. Tips are expensive because they are made such that they have no exposed seats and as such are much less likely to be damaged. Ernie feels their valves are somewhat less robust than others.

Airco Once king of the industry, Airco (the company) got broken up, part went to Concoa and part went to Koike. Both now make torches and Koike is said to make very good Airco tips. Fuel mixed in tip. Ernie feels their valves are also slightly less desirable. Airco tips are expensive and have exposed seats. Airco combo torches are available in the smaller 700 series, and the larger 800 series. The 800 series has stainless steel threads where the tips and cutting attachment connect, making them much more durable than most other torches that have brass threads. The 800 series also have bigger stronger valves than the 700 series.

Victor very common, parts everywhere, cutting tips least expensive. Fuel mixed in torch body. Best valves available. In their combo torches, the 315 is larger, heavier, has much better valves. The 100 is small, light, and thus easier to store. The 100 has variants: the thread on top can be smaller (indicated by the prefix J i.e. J100) or larger for the plain 100 series. The J100 handle takes a 1250 or 1260 cutting attachment and the 100 handle takes the 1350 attachment. Modern Victor torches (indicated by FC suffix) have flash arrestor/check valves built in, which can be more compact than separate flash arrestor modules but these can clog and sometimes they can't be cleaned so this can lead to an expensive repair.

The smallest generally available torches are called 'aircraft torches' since they were once used to weld aluminum aircraft skins. They make excellent jewelry torches. The smallest torch available is the Smith Little Torch, which has synthetic sapphire orifices in the smallest tips.

Torches are generally made of brass, a soft metal, except the larger industrial cutting torches which can have manganese bronze, monel or even stainless steel heads. Any threads which are exposed are subject to being damaged by careless handling such as being banged around in a toolbox. Therefore such threads should never be exposed; something should always be threaded onto them. DIT stores their cutting torches attached to torch leads. You can cut the connecting nuts off old torch lead before discarding it, and use the nuts to protect exposed threads on both torches and regulators.

On combination torches, do not tighten the nut which secures the welding tip or cutting torch attachment more than finger tight, even if it has wrench flats. The wrench flats are intended for disassembly if the nut doesn't come off easily. Tightening the nut with a wrench can be tough on the O-rings.

O-rings are generally Viton material (Victor uses Hypalon - chlorosulfonated polyethylene - according to an older "Welding, Cutting & Heating Guide"), but may be in proprietary sizes. O-rings should be inspected periodically for cracks or to see if they have lost their roundness in cross-section.

If a cutting torch pops the first place to look is at the tip. The tip seat may be damaged, or the tip may be out of round, or the seat may be dinged. If the tip is damaged, replace it. If the tip seat is damaged, take the torch in for repair, it can generally be reamed true, except for Smith cutting torches, which can't be reamed if the sealing edge is damaged.

Hoses & Connectors

Hose types Twin-lead welding hose comes in 2 grades Grade R is for use with acetylene only Grade T is for use with any fuel gas including acetylene

Hose size 3/16" ID hose OK for welding & maybe light cutting short length of 3/16" hose compacts for storage in a toolbox not suitable for rosebud heating or heavy cutting 1/4" ID hose is common in many shops, OK for welding and most cutting 3/8" is the largest size used with most torches, for very heavy cutting, i.e. over 4" 1/2" or larger hose may be needed for extremely heavy cutting or heating

Connectors Any scored connector (the flat faces where the wrench fits have a line scored across all of them, like it's "wearing a belt") has left hand threads. Torch leads come in A and B sizes (and larger). B size is 9/16-18 and A size is 3/8-24. B size fittings can be used for 3/16", 1/4" or 3/8" hose. A size fittings are used on 1/8" or 3/16" hose for very small torches.

Generally, fuel gasses use LH threads except for A, B and MC bottles which do not. Quickchange connectors are available at a price, and these are a great convenience and Ernie uses them, but cautions, "IF you have to break down your setup or swap torches often, quickchange connectors are great. If your setup never gets taken apart then skip them.

Obviously oxygen and fuel gasses should not be allowed to ever mix in the hose; a mixture of oxygen and acetylene can be very explosively unstable indeed for example. To this end, there are two types of safety devices commonly used. The first is a set of check valves. Check valves allow gas flow in only one direction. Installed at the torch, check valves can prevent unsafe situations. For example, suppose a user draws enough oxygen out of a depleted cylinder so that the oxygen pressure drops below the fuel gas pressure. In that case the fuel gas could back-flow into the oxygen line, which can be extremely dangerous. Flash arrestors are designed to extinguish a flame internal to the torch, preventing the flame front from reaching back into the hose. Flash arrestors are much more expensive than plain check valves, but they often include check valves.

Many currently made Oxy/fuel-gas torch models have built in check valves.

Strikers Conventional These use synthetic flint and steel to generate a spark. These strikers are very inexpensive and can last for many years. The steel generally doesn't wear out, and the flints are renewable inexpensively. What goes wrong with conventional strikers is that they get bent or rusty. Piezoelectric Ernie loves these. He says they never wear out, ever. If they stop sparking, a sharp rap on the welding table will always make them spark again. Neither striker technology works very well if wet, but the conventional striker at least works somewhat while the piezoelectric type basically doesn't work at all if wet. Keep them dry. It is strongly discouraged to light a torch with a disposable lighter, although it is done a lot, perhaps foolishly.

Eye protection Gas welding and cutting requires a #5 lens. Brazing and silver soldering requires a #3.

Aluminum gas welding requires either a Gold coated didyminum or gold coated cobalt lens. Old fashioned plain cobalt or didymium lenses are very dangerous since they do not block UV. There is also a special aluminum welding lens made by

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called the TM2000.

Gas welding rod Don't mix up gas welding rod and TIG filler rod. TIG filler rod is designated ER70S-2, and gas welding rod is designated R45.

How to connect, ignite, extinguish & shut down an O/A torch; best practice Connect the regulators and hoses Ensure the regulator key is completely released (unscrewed until slack) Briefly crack each cylinder in turn before attaching the regulator to remove any debris in the valve head Attach the regulators to the tanks, attach the hoses and then again crack each cylinder valve and turn in the regulator key to allow gas to flow for a short time to blow any debris from the hoses, then back the regulator key back out and shut off the cylinder Attach the torch Slowly crack each cylinder in turn until tank pressure shows. Open the gas cylinder about one full turn; open the oxygen cylinder all the way until hand-tight against the top. (This stops oxygen from leaking.) Slightly open each valve on the torch in turn, adjusting the regulator to the desired flowing pressure, then shutting off the torch. With a solution of dishwashing soap in water, leak-test the connections. The torch is now ready for lighting. Slightly open the torch fuel valve and light the torch. Continue opening the torch fuel valve until the soot just disappears from the flame. Then slowly adjust the oxygen valve until the desired flame (carburizing, neutral, oxidizing) occurs. The torch is now ready for welding. Shut off the torch by first shutting off the fuel. However, if a cutting torch pops out and a loud "singing" sound is heard from the torch it means the flame is burning inside the torch body and in this case the oxygen should immediately be shut off first. To shut down the torch and regulators, first extinguish the torch (as above) and then shut off each cylinder in turn. After shutting down each cylinder, open the respective valve on the torch to bleed the pressure out of the regulator and then spin out the regulator key until all the spring pressure is released and the regulator key spins freely, then shut the torch valve. The system is now properly shut down and ready for disassembly or storage.

How to ignite an O/LP torch All of the above procedure is correct but it is often easier to light an oxygen/LP torch if a small amount of oxygen is allowed to mix with the LP fuel gas before lighting. Harold (from Hansen & Miller) asserts that the best way to light an O/LP torch is to slightly open the fuel valve, light the flame, then add a little oxygen, then open the fuel valve some more, then again add more oxygen, then open the fuel valve to the final setting and then finally adjust the oxygen valve for the correct flame.


Torch setup, connection & lighting on several fuels & torch types

Torch welding basic techniques on 16 ga. sheet steel

Flat bead don't wear gloves, bend the welding rod about 75°, hold torch in your right hand and the welding rod in your left (assuming you're right- handed), weld right to left (forehand), using the torch to make a puddle, then dipping the rod directly into the puddle briefly then pulling the rod back out, then immediately engaging the puddle with the torch again. The torch and wire should more or less line up, with your hands out of line. In that way, the welding gas will reflect and act as preheat. Pic:

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Butt joint tack both ends first, otherwise similar, but the edges will melt a lot faster than a flat bead Tee joint need more heat than a butt joint, tack both ends first, also here you're joining an edge to a flat, so the edge will want to melt first, so keep the heat more on the flat and make sure to add the filler rod to the back of the puddle. The torch flame moves rapidly back and forth along the joint to keep the weld puddle fluid. Outside corner joint uses a smaller flame than a butt joint; tack both ends first, arrange so joint is horizontal and at top of vee, don't need any filler rod, just wash the puddle along with the torch Lap joint worst case for edge/flat difference, here flame is aimed 1/8" from edge of top piece, while filler rod is added between the flame and the edge. Be very aggressive in feeding the filler rod or the top edge will melt away.


Cutting tips Cutting tips are often fouled right at the tip with slag. It may be possible to hold the lit tip against a piece of pine until sufficient heat builds up in the tip to cause it to pop out, which often forces the fouling slag out. Often a tip is slightly dirty and can be cleaned with a set of tip reamers. Tip cleaners should be used very gently and carefully as they perturb the precision tip geometry.

O/A These are one-piece tips, generally made of copper. O/LP These are two-piece tips, which are not always made of copper. The inner piece is generally recessed slightly from the outer part. Although there are many types of tips made for different LP gasses, they are often similar and may work acceptably if interchanged between different LP gasses. In other words, a MAPP tip may well work well with propane or chemtane or propylene.

Never ever use any LP tip with acetylene, it will melt the end off.

Some safety issues

Hot fragments can still be red-hot on the floor, and they will melt right into and maybe even through your boots. Watch carefully where you step, and it doesn't hurt to have a blacksmith-type slack tub around full of water, so if you do get a "hot foot" just dunk in your whole foot, boot and all, fast!

Falling cut-off steel can be heavy, sharp and red-hot, a wicked combination.

Hot slag (sparks) hold a lot more heat than welding spatter - a built-up ball of slag dropping on you can make a 3rd degree burn.

Loose threads on jeans can ignite, it's a real good idea to have a fire extinguisher in the area, test it regularly, and know how to get to it and use it.


Victor Acetylene Cutting Tip Chart

- Cutting Tip Series 1-101, 3-101, 5-101

METAL TIP OXYGEN FUEL SPEED KERF THICK. SIZE PSIG PSIG I.P.M. WIDTH 1/8 000 20-25 3-5 28-30 .04" 1/4 00 20-25 3-5 27-30 .05" 3/8 0 25-30 3-5 24-28 .06" 1/2 0 30-35 3-5 20-24 .06" 3/4 1 30-35 3-5 17-21 .07" 1 2 35-40 3-6 15-19 .09" 2 3 40-45 4-8 12-15 .11" 3 4 40-50 5-10 9-12 .12" 4 5 45-55 5-10 8-11 .15"

CAUTION: AT no time should the withdrawal rate of an individual acetylene cylinder exceed 1/7 of the cylinder contents. If additional flow is required, use an acetylene manifold system of sufficient size.

Airco Acetylene Cutting Tip Chart

Metal Cutting Oxy(psig) Acet.(psig) Hand(ipm) Machine(ipm) Thickness Size #

¼ 0 30 3 16.0 - 18.0 20 3/8 1 30 3 14.5 - 16.5 19 ½ 1 40 3 12.0 - 14.5 17 ¾ 2 40 3 12.0 - 14.5 15 1 2 50 3 8.5 - 11.5 14 1½ 3 45 3 6.0 - 7.5 12 2 4 50 3 5.5 - 7.0 10 3 5 45 4 5.0 - 6.5 8 4 5 60 4 4.0 - 5.0 7 5 6 50 5 3.5 - 4.5 6 6 6 55 5 3.0 - 4.0 5

Gas pressures are for hose lengths up to 25?. Increase pressure for longer lengths of hose.

Rob wrote:

Reply to
Grant Erwin


(snip lots more good stuff)

Grant, it isn't quite this clear cut. My cylinders (Mnpls area) have various supplier's marks on the headstamps. I swap MT's for fulls, but the supplier(s) and I agree that I own a certain number of various sized cylinders. If I want to get them filled at a different supplier then I merely need to transfer ownership records to that supplier -- which is just a matter of a phone call from supplier to supplier. They do that routinly, no hassle at all. I do not pay any lease charges.

The smaller ones (40 cu ft and under) don't have that requirement; about anyone will fill them and there is no record of ownership.

Reply to
Don Foreman

You're right, Don, but the text is what Ernie teaches and it's a real good place to start. He teaches people to be leery buying used welding cylinders. It is possible that a used cylinder with raised lettering on the neck ring is an owner cylinder, but generally it isn't.


D> >

Reply to
Grant Erwin

This can't be right. Should that be 47 cubic feet per HOUR? I can't believe you can empty an Acetylene tank in just 7 minutes!


Reply to
Jon Elson

Yup. Certainly a good practice would be (as you alluded) to ask the seller where he gets them filled and then call that place (before buying them) to inquire about what must be done so you can get them filled later. If the seller balks at that, walk away from it.

Reply to
Don Foreman

Nice catch. Corrected. - GWE

Reply to
Grant Erwin

If you lay an acetylene bottle on its side you are not supposed to use it until it has been sitting upright for up to 24 hours. The time varies from different sources. Some say for as little as four hours. Randy

I took just the bottle back to the store and exchanged it, but on the way home it tipped over

Thanks for your help, Rob Dennett

Reply to
R. Zimmerman

Yes, but if I did, do I just need to wait 24 hours, or does my system need servicing?

Thanks, Rob Dennett

Reply to


Thanx for Ernie's notes on welding. I printed them and stuck it in the "welding dept." of my shop. Ernie, if you are reading -- many thanks to you for the original material.

Bob Swinney

Reply to
Robert Swinney

You should be OK. The torch will probably sputter a little until it gets the acetone out of it's system... I loaded mine up once trying to run a big rosebud on tanks that were too small (actually, it works OK when the tank is nearly full, but, when it gets much below a half, it starts drawing acetone...) and seem to have suffered no ill effects. And a buddy of mine had an employee try to use up the last bit of acetelyne and had put a significant amount of the acetone through the torch before he caught him. It didn't seem to hurt the torch any, but the gas vendor was none too happy...


Reply to
Jerry Foster

Well, I finally got the opportunity to fire it up, but the flame pulsed stronger and softer. Is this just a case of acetone needing to burn itself out?

BTW, I was looking at wikipedia's page on oxyacetylene welding and cutting and it recommended shutting off the acetylene valve first. I couldn't remember which one I was taught, so I followed those instructions, which caused a nasty pop. I thought that one should probably shut off the O2 first, but again, this might be an acetylene problem. Is it?

Thanks for your help, Rob

Reply to

It sounds like a regulator problem to me. Can you borrow a known-good acetylene regulator to try?

Shutting off the acetylene first is the recommended procedure UNLESS you are using a real big heating tip, in which case it might pop loudly. In that case, what I do is to step from one valve to the other until both are low, then shut off the oxygen first.


Reply to
Grant Erwin

Sounds like a leaking diaphragm.


"Deep in her heart, every moslem woman yearns to show us her t*ts" John Griffin

Reply to

Is that something that can be repaired? What is it likely to cost?

Thanks for your help, Rob

Reply to

Cost to repair a given regulator would depend on what brand it is because of availability of parts. Some can't be repaired. In my area, rebuilt name-brand regulators can often be found at the welding store for under $40 with no tradein.

Reply to
Don Foreman

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