Oxy/acetylene cutting tip question

[Tracs]

Hello,

I have a nice Harris torch and big tanks of Oxygen and Acetylene I got a year ago. I have never used it until last week.

When I originally bought a tip they gave me a #2. I never noticed. I was trying to cut some 3/8" steel plate and was having a heck of a time. It would start cutting and then stop. It didn't matter if I went slow or fast.

I now have a #0 tip.

Would using the #2 tip with 40psi Oxy and 7psi of Acetylene have been way too much for the 3/8" plate and that is where my problems were coming from?

I don't have anything to cut to try out the #0 tip. Was just wanting some confirmation.

 

[Mr_fixit]

I'd use a 0 tip on 3/8". I think the only size tips I ever used were 0 and 00. so my guess is maybe. My guess is also that you need to learn the proper technique of heating and then cutting.

 

[royce]

Tracs,
A #2 Harris tip is designed to cut 1" through 2" plate
A #0 is designed to cut 3/8" through 5/8" plate
If you google Harris tip chart it will show the tip sizes, gauge settings and travel speed.
Hope that helps.

Royce

 

[gearhead1]

Royce,

I’m just curious since you do a lot of fab work, do you use propane or acetylene?

 

[royce]

Royce,

I’m just curious since you do a lot of fab work, do you use propane or acetylene?

I use acetylene, I have worked in shops that used propane, but always preferred acetylene.

Royce

 

[joe49]

Clean the #2 tip, pressures are on high side for tip and the tip size is larger than needed for 3/8'' but should work. If you still have trouble you likely need practice.

 

[dr_clyde]

Yeah, #2 is for sure a bit big for that thin of steel.

I run a #0 or #1 for general shop cutting tasks.

I also much prefer acetylene vs propane. Acetylene is still relatively cheap and I use the torch often enough for fine soldering and brazing work that its not worth the effort to swap out for propane to just save a few bucks here and there.

If you're doing a TON of heating, propane is capable of producing more BTUs/hr than acetylene for a given cylinder size, as there isn't a withdrawal rate limit on propane. The TEMPERATURE of acetylene is hotter, but you get a higher VOLUME of heat out of propane.

For just general shop use, there isn't enough of a cost difference to warrant the hassle of propane IMO.

 

[Kaizen]

Op was this a new setup or used? If used maybe hose or regulator causing drop in pressure randomly. Also I’m assuming you have had the tanks standing for at least a few days right?


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[MoonRise]

A Harris #2 6290 cutting tip is way oversized for cutting through 3/8" plate.

As mentioned, it is sized to cut through 1-2" thick plate.

Pressures for a #2 6290 tip are 40-45 psi O2 and 10-15 psi acetylene.

It is going to flow 20-30 cfh of acetylene, so you should run that sized tip with AT LEAST a 140-210 ft3 acetylene cylinder (or the equivalent capacity of manifolded cylinders) to stay under the 1:7 acetylene flow safety rule.

It is also going to flow 20 cfh of O2 for the preheat flames, and jump to 180-195 cfh when you hit the cutting lever.

If you have a two-piece 6290AC (two-piece heavy-preheat) tip, the #2AC tip calls for 40-65 psi O2 flowing at 161-252 cfh when you hit the cutting lever and acetylene pressures of 8-15 psi with 18-36 cfh of acetylene on the preheat flames.

That means a minimum acetylene cylinder size (single or manifolded) of 126-252 ft3 for the 1:7 acetylene flow rate safety rule.

If you have a different model cutting tip that you were/are using (Harris makes Victor-style stuff too), then you would have to look up the pressures/flows for those tips.

 

[Tracs]

Op was this a new setup or used? If used maybe hose or regulator causing drop in pressure randomly. Also I’m assuming you have had the tanks standing for at least a few days right?


Sent from my iPhone using Tapatalk

Hoses and regulators are new. Complete torch was refurbished by a welder supply company. Tanks have been standing for a year.

 

[Tracs]

A Harris #2 6290 cutting tip is way oversized for cutting through 3/8" plate.

As mentioned, it is sized to cut through 1-2" thick plate.

Pressures for a #2 6290 tip are 40-45 psi O2 and 10-15 psi acetylene.

It is going to flow 20-30 cfh of acetylene, so you should run that sized tip with AT LEAST a 140-210 ft3 acetylene cylinder (or the equivalent capacity of manifolded cylinders) to stay under the 1:7 acetylene flow safety rule.

It is also going to flow 20 cfh of O2 for the preheat flames, and jump to 180-195 cfh when you hit the cutting lever.

If you have a two-piece 6290AC (two-piece heavy-preheat) tip, the #2AC tip calls for 40-65 psi O2 flowing at 161-252 cfh when you hit the cutting lever and acetylene pressures of 8-15 psi with 18-36 cfh of acetylene on the preheat flames.

That means a minimum acetylene cylinder size (single or manifolded) of 126-252 ft3 for the 1:7 acetylene flow rate safety rule.

If you have a different model cutting tip that you were/are using (Harris makes Victor-style stuff too), then you would have to look up the pressures/flows for those tips.

I switched to a #0 tip.

I don't know the capacity of the acetylene tank. The Oxygen tank is medical grade from a buddy and has a tag that says it filled to 3.37 m3 (120 cu ft).

I don't know the science behind gas withdrawal, but I hope I won't have a problem with the size of tanks I have.

 

[ItsNemo]

I switched to a #0 tip.

I don't know the capacity of the acetylene tank. The Oxygen tank is medical grade from a buddy and has a tag that says it filled to 3.37 m3 (120 cu ft).

I don't know the science behind gas withdrawal, but I hope I won't have a problem with the size of tanks I have.

Acetylene isn't something you should just hope you won't have problems with...take the time to learn. The 1:7 rule means you shouldn't draw more than 1/7th the tank capacity.

See:
https://www.harrisproductsgroup.com/en/blog/2019/august/what-is-the-1-7-acetylene-rule.aspx

 

[harley jim]

Looks the same size as mine. Like others have said tip is a bit large. You need to heat your metal until it is red before you hit the oxy lever. Practice will make the difference. Get some scrap and practice.

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[MoonRise]

That acetylene cylinder looks like a 75 ft3 one.

Absolutely read and understand the 1:7 rule for the acetylene withdrawal rate.