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What's the smallest O/A you'd get?

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  • What's the smallest O/A you'd get?

    At home where I do most of my light (very) stuff I just stepped up to a 60 acet (I think, next smaller is a b I think) so I can use standard gauges. My Oxy is still an 80. But up at the camp I want a small o/a set. I have another buzz box and 110v mig and the O/A is missing. Real light work, cutting some small holes, heat to bend, maybe some brazing. I see the little 10 Acet and 20oxy kits, I know they are mostly for AC guys. But how much cut time can you get out of one? I like the size of them and a Victor set (real deal, with tanks) can be had on Ebay for $296 with free shipping. This comes complete with cutter and welding tips and regulators.

    But are these really to small even for light use and cutting?

    Thanks,
    Rob
    __________________
    HH140 and c-25
    Lincoln 220v AC buzzbox
    120/80 O/A
    Second Location
    HF 220v gasless mig
    Hobart AC Stickmate
    80/B O/A

  • #2
    I looked at the AC portable kit earlier this year just because it looked like a cheaper to buy the AW1A torch and regulators etc if you sell the tiny tanks. The problem I eventually saw was that the small ace tank is really too small to do a lot of cutting with because of the 1/7 rule on drawing the Ace tank down.

    You can estimate the time any Smith tip (don't know where online you get it for Victor) will burn from the consumption data in the Smith catalog. (link below). For the MC 12-00 tips supplied with the AC set, it looks like about 6 CFH of ACE when cutting.

    The MC tanks are 10 CF, so theoretically you can draw up to 1.4 CF in an hour without violating the rule. Since the 12-00 tip consumes about 6 CFH, you should be able to cut for about 14 minutes every hour, if I understand the rule. (*** Edit - keep reading this thread to see this is not the way the rule is supposed to be applied, according to pumpkinhead, who actually knows what he is talking aout. I don't want anyone blowing themselves up due to my misunderstanding a rule ****)


    Of coure the 20 CF oxygen tank would only cut for about 2/3 of an hour total with this tip's 30 CFH oxygen appetite.


    I should point out I don't have one of these, so this iis just what I have read and understand.

    http://www.smithequipment.com/produc...ges/page39.pdf

    By the way the gas consumption data on the tiny tips you can use with the AW1A also shows why the they don't consume much gas compared to a bigger torch, when welding on small stuff

    http://www.smithequipment.com/produc...ges/page44.pdf
    Last edited by smyrna5; 11-05-2007, 01:01 PM.
    Lincoln 175HD
    Miller Thunderbolt AC/DC
    Smith AW1, Dillon (Henrob) Mark III & Smith Quickbraze Little Torch

    Comment


    • #3
      Smyrna, et. al,
      unfortunately it's not like duty cycle (x min. use per time period), it is a steadfast rule, you can safely draw 1/7th the volume of the cylinder, i.e. to use the 00 tip you'd need 42CF minimum. this is due to the acetylene coming out of solution, basicly it's boiling out (bubbles) of the acetone, these bubbles, if too many are produced at a time, carry acetone into the reg., into the hoses, and out the tip, depleteing the cylinder of acetone, less solute/less acetylene can be dissolved, acetylene gas at pressures greater than 15psi, BOOM !!!!

      Comment


      • #4
        Well, I thought I understood the rule, but oviously I don't. So you are saying that you multiply the CFH times 7 to get the minimum size cylinder correct?

        I do need to understand it (as does everyone contemplating o/a), because at some point, I am pretty sure a set of tanks, gauges, and torch is going to make me an offer I can't refuse.

        I do remember deciding that the MC size cylinder would not be of much use for cutting, and wondered why they even include a cutting attachment with it.
        Last edited by smyrna5; 11-05-2007, 12:37 PM.
        Lincoln 175HD
        Miller Thunderbolt AC/DC
        Smith AW1, Dillon (Henrob) Mark III & Smith Quickbraze Little Torch

        Comment


        • #5
          i guess a good visualization is my old standby, the bottle of soda, think of a shook up soda with a twist off cap, if you were dilgent you could just crack the seal and let the gas slooooowwwwwly escape, you could also just remove it and take a Dr. Pepper shower, same thing is going on in the acetylene bottle, you can let the gas out so it just fizzes (correct tip for cylinder size), or use a too large tip and equate the removal of a cap and the ensuing acetone bath for your regulator/hose/torch. and just as after you took the Pepsi washdown, there is considerably less liquid in the cylinder (bottle).

          Comment


          • #6
            Originally posted by smyrna5 View Post
            I do remember deciding that the MC size cylinder would not be of much use for cutting, and wondered why they even include a cutting attachment with it.
            same reason the come with those nice shiny brand spanking new cylinders in that tote, cause it looks nice. then you take it to be filled (they come empty) and you get a set o' jugs that have been through he11. that and the fact they figure you'll eventually step up in tank size.


            Originally posted by smyrna5 View Post
            So you are saying that you multiply the CFH times 7 to get the minimum size cylinder correct?
            yes, typically you determine the largest tip you'll use then check the 'flow chart' (nyuck, nyuck) multiply by seven and get the size tank available that's larger than that number, that is to say if your number is betwixt two sizes you'd get the larger, even if it's real close I'D go larger.
            but remember a tip using large quantities of fuel also use large quantities oh oxygen, makes for a bad day cutting when you have a big ol' acetylene and a oxygen fart in a bottle.
            Last edited by Pumpkinhead; 11-05-2007, 12:55 PM.

            Comment


            • #7
              The Smallest??...

              "Good Enough Never Is"

              Comment


              • #8
                Now, that was funny Hotfoot!

                By the way, here is a tip chart for the Victor tips, but notice the way they explain the 1/7 rule:

                "Acetylene cylinder gas withdrawal should not exceed 1/7 (15%) of cylinders contents per hour. "

                No wonder I was confused, since people plaster this 1/7 interpretation all over the internet as if it were a duty cycle number. This misinformation wouldn't be so bad if it weren't a potential safety issue.

                ---> Victor Tip Chart

                At least the Smith Catalog correctly defines it the same way as pumpkinhead:

                http://www.smithequipment.com/produc...ges/page87.pdf



                Aye Chihuahua!
                Last edited by smyrna5; 11-05-2007, 01:52 PM.
                Lincoln 175HD
                Miller Thunderbolt AC/DC
                Smith AW1, Dillon (Henrob) Mark III & Smith Quickbraze Little Torch

                Comment


                • #9
                  Originally posted by Hotfoot View Post
                  The Smallest??...

                  I'm not sure those will even light a smoke!!
                  __________________
                  HH140 and c-25
                  Lincoln 220v AC buzzbox
                  120/80 O/A
                  Second Location
                  HF 220v gasless mig
                  Hobart AC Stickmate
                  80/B O/A

                  Comment


                  • #10
                    Originally posted by Pumpkinhead View Post
                    Smyrna, et. al,
                    unfortunately it's not like duty cycle (x min. use per time period), it is a steadfast rule, you can safely draw 1/7th the volume of the cylinder, i.e. to use the 00 tip you'd need 42CF minimum. this is due to the acetylene coming out of solution, basicly it's boiling out (bubbles) of the acetone, these bubbles, if too many are produced at a time, carry acetone into the reg., into the hoses, and out the tip, depleteing the cylinder of acetone, less solute/less acetylene can be dissolved, acetylene gas at pressures greater than 15psi, BOOM !!!!
                    How come they don't make a regulator that will not allow more than 15 psi?
                    Ed Conley
                    Screaming Broccoli, Inc
                    http://www.screamingbroccoli.net/
                    MM252
                    MM211
                    Miller Passport Plus, Spoolmate 100
                    TA185
                    SO 2020 Bender
                    Miller 125c Plasma
                    "Hold my beer while I try this!"

                    Comment


                    • #11
                      Originally posted by Broccoli1 View Post
                      How come they don't make a regulator that will not allow more than 15 psi?
                      BOOM

                      Regulator will go above 15 psi. Acetylene is not stable at higher pressure with safety margin breaking apart into different compounds with explosive force.

                      If your using your acetylene regulator to supply Propane you can set regulator higher than 15 PSI.

                      Comment


                      • #12
                        Originally posted by Roger View Post
                        BOOM

                        Regulator will go above 15 psi. Acetylene is not stable at higher pressure with safety margin breaking apart into different compounds with explosive force.

                        If your using your acetylene regulator to supply Propane you can set regulator higher than 15 PSI.
                        I understand the Boom part but why not make an Acy Regulator that does NOT go above 15 psi so there is no chance of BOOM ?
                        Ed Conley
                        Screaming Broccoli, Inc
                        http://www.screamingbroccoli.net/
                        MM252
                        MM211
                        Miller Passport Plus, Spoolmate 100
                        TA185
                        SO 2020 Bender
                        Miller 125c Plasma
                        "Hold my beer while I try this!"

                        Comment


                        • #13
                          There are regulators made preset to one pressure by tight tolerance and maybe shims to fine tune pressure. (I have one that doesn't need shims.) Then a relief valve to insure no over pressure. Both regulator and relief valve will fail in different mostly predictable ways sooner or later. Even the gage will fail that you use to monitor critical pressure. Now days scuba regulators manufactures require annual overhaul by trained certified repair person. The regulator can fail anyway in between repairs.

                          By having regulators set by hand adjustment while monitoring a pressure gage by trained weldor with each use. You should notice when regulator doesn't hold adjustment setting, gage sticks, notice leaks, and your able to set pressure to your exact needs often much lower than 15 psi and higher when not using Acetylene. This is safer and should shift much of the liability away from manufacture. I say maybe because of USA's twisted civil law and I just saw the movie.

                          Comment


                          • #14
                            Originally posted by Roger View Post
                            There are regulators made preset to one pressure by tight tolerance and maybe shims to fine tune pressure. (I have one that doesn't need shims.) Then a relief valve to insure no over pressure. Both regulator and relief valve will fail in different mostly predictable ways sooner or later. Even the gage will fail that you use to monitor critical pressure. Now days scuba regulators manufactures require annual overhaul by trained certified repair person. The regulator can fail anyway in between repairs.

                            By having regulators set by hand adjustment while monitoring a pressure gage by trained weldor with each use. You should notice when regulator doesn't hold adjustment setting, gage sticks, notice leaks, and your able to set pressure to your exact needs often much lower than 15 psi and higher when not using Acetylene. This is safer and should shift much of the liability away from manufacture. I say maybe because of USA's twisted civil law and I just saw the movie.
                            Thanks- makes sense
                            Ed Conley
                            Screaming Broccoli, Inc
                            http://www.screamingbroccoli.net/
                            MM252
                            MM211
                            Miller Passport Plus, Spoolmate 100
                            TA185
                            SO 2020 Bender
                            Miller 125c Plasma
                            "Hold my beer while I try this!"

                            Comment


                            • #15
                              Originally posted by Pumpkinhead View Post
                              i guess a good visualization is my old standby, the bottle of soda, think of a shook up soda with a twist off cap, if you were dilgent you could just crack the seal and let the gas slooooowwwwwly escape, you could also just remove it and take a Dr. Pepper shower, same thing is going on in the acetylene bottle, you can let the gas out so it just fizzes (correct tip for cylinder size), or use a too large tip and equate the removal of a cap and the ensuing acetone bath for your regulator/hose/torch. and just as after you took the Pepsi washdown, there is considerably less liquid in the cylinder (bottle).
                              Nice.

                              Couldn't have said it better, if I could have thought of the analogy!

                              Back to Rob's question: The mini-pack sets are not really intended for cutting chores. They are mostly utilized as heat sources for sweating pipes, tubing, etc.

                              Still, for limited applications, they can be effective. Don't plan to cut rebar all day with one of these kits, but if you need to cut some hinges from a gate, or similar tasks, they work okay.

                              The 1/7th rule is important, but you [B]can[B] violate it for brief periods before acetone percolation occurs. I've used a #4 Victor cutting tip on a 40 CF C²H² jug for five minutes or so with no ill effects, but I wouldn't want to push it much past that.

                              Hank
                              Last edited by hankj; 11-08-2007, 01:57 AM.
                              ...from the Gadget Garage
                              MM 210 w/3035, BWE
                              HH 210 w/DP 3035
                              TA185TSW
                              Victor O/A "J" series, SuperRange
                              Avatar courtesy of Bob Sigmon...

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