Cutting Torch Question

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Hey y'all,Interesting issue I had yesterday with my OA torch. I was using a 000 tip on my Victor to cut some rather thin (3/32) metal. No change in setup from the last time I used it. I usually used 3-4 PSI gas and around 20psi for oxygen. Clean tip.When I went to set the acetylene pressure I noticed if i ran around 3-4 the regulator would "pulse" - if I jacked it up a bit to 5-6 it smoothed out. Kind of a cool effect with the torch lit at 3-4 with the pulsing, but hardly effective.What gives? Could the colder temperatures and/or moisture be the problem? Regulator calibration? I haven't had the regulator off for months &, like I said, nothing in my setup has changed. Even after going up with the pressure and returning to 3-4, it pulsed.Ended up running a little more acetylene than need to be to finish the job, but don't want to make it a habit.ThanksMike
Reply:Is the bottle running low?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Cold weather can cause that, if the cylinder is almost empty.   JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Thanks - yeah I'll check it when I get home , but i thought it was good to go - could be the colder temps reacting to emptier tank. last time I used it, it was fine - but about 30 degrees warmer!Thanks all!
Reply:Yeah, I had 120-130PSI in the tank - a little low - but it was also about 15-20 warmer today. It was back to it's old self. Smooth at 3-4 PSI.  Thanks folks.....
Reply:Originally Posted by mtncrawlerYeah, I had 120-130PSI in the tank - a little low - but it was also about 15-20 warmer today. It was back to it's old self. Smooth at 3-4 PSI.  Thanks folks.....
Reply:Will explain, in detail, if anyone wants to know.  JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Originally Posted by weldgaultWill explain, in detail, if anyone wants to know.  John
Reply:Yes, I would like it explained! Right on with the "more to it than that" comment. I guess where I was coming from was that for a given volume of gas at a colder temperature, won't I see less pressure at the regulator? Can't the pressure be used to measure changes or  "relative" amounts of gas in the cylinder? Please enlighten!
Reply:Did a little more checking - read a acetylene data file from Airgas - and I think I understand a little more about the determination of the amount of acetylene in the cylinder.Would like to hear your thoughts though John!Mike
Reply:I think John will talk about the weight of the dissolved acetylene in the acetone, and relate that to the capacity of the tank to find the amount of gas, the only reason I can think of pulsing is if something in the regulator is jamming, or if it's slightly off calibration and you only getting enough flow for it to pulse open and closed, You are probably running quite low on acetylene, go get it filled and see how much they put in.
Reply:Originally Posted by mtncrawlerYes, I would like it explained! Right on with the "more to it than that" comment. I guess where I was coming from was that for a given volume of gas at a colder temperature, won't I see less pressure at the regulator? Can't the pressure be used to measure changes or  "relative" amounts of gas in the cylinder? Please enlighten!
Reply:Thanks for the responses John!A little more info to my original question. My tank size is #4, 145cu/ft tank. I believe this subject is being covered in another post - can you tell me what I would expect to see when it's full? Thought it was around 250?Mike
Reply:Originally Posted by mtncrawlerThanks for the responses John!A little more info to my original question. My tank size is #4, 145cu/ft tank. I believe this subject is being covered in another post - can you tell me what I would expect to see when it's full? Thought it was around 250?Mike
Reply:Thanks John - Yeah pressure changes with temp make sense. To help me understand even more, given that the temps that I'm seeing here were around 10-20 degrees F - can you necessarily draw any conclusions about what I have remaining in the tanks given the 120psi I'm seeing, or will it just take further experiences over several refills?I just don't have a lot of history with acetylene use (at least not for many years), so I'm just trying to learn all I can...Mike
Reply:Originally Posted by mtncrawlerThanks John - Yeah pressure changes with temp make sense. To help me understand even more, given that the temps that I'm seeing here were around 10-20 degrees F - can you necessarily draw any conclusions about what I have remaining in the tanks given the 120psi I'm seeing, or will it just take further experiences over several refills?I just don't have a lot of history with acetylene use (at least not for many years), so I'm just trying to learn all I can...Mike
Reply:I Know it's not a true measure, HOWEVER, An older friend once told me this "formula", it is fairly accurate. This is a seat of the pants method, not for those that iron their underwear. With acetylene, you loose two ponds pressure for every degree below 70 degrees. One example, your tank shows 100# in the heated shop, you put the tank on the truck, drive a while at 20 degrees, you now show 0#.  Put the tank in the cab, heater on high, have a coffee, or two,  go back to work. Do not put it in front of the construction heater etc.Just my  opinion, not from a book, just from the road.Howes Welding Inc.www.howesweldinginc.com
Reply:Just a guess, no evidence that is true, but it could be as good as any other guess.   JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Here we go John,TW = 68.6lbs (Wasn't sure if the -.6 was part of the actual weight..check pic)Full Weight (minus the cap) = 76.8lbsDifference = 8.2lbs8.2lbs x 14.7cuft per lb = 120 cu/ft.Wow - I have plenty of acetylene left in this tank!  (Wait I better not celebrate yet...) Check my work - I even included a pic of the cylinderMike
Reply:That is the way it is done in an acetylene Plant!!  Good work and you are right.  Now if everyone would do that, we would, as a group, be better off than the LWS, who is trying to get into your pockets.  JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Thanks John!An invaluable lesson and I really appreciate your patience with my questions. Been reading some of the other recent related posts as well - nice work!Mike
Reply:Thanks, I hope I can be of more help in the future.   JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :