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  • Gas surges at start of flow

    So i decided to test the gas flow rate at the nozzle on some of out robotic welders (using this http://stores.ae-welding-industrial....tester-ck-gft/ ) and found that the flow was about 4-5 CFH less at the nozzle than the regulator. What I also found was there was a 2-3 second surge of gas that maxed out the flow meter, 50+CFH before dropping to the 35-40 range. There is a good bit of line between the regulator and the robot, about 25 feet, and its having an accumulator effect. Has anyone used one of those surge protectors with any results? Were there any downsides to this? Thanks.

  • #2
    These guys at NETWELDING claim to have a device that cures this problem..

    http://www.netwelding.com/Shielding_...l_Download.pdf

    .

    *******************************************
    The more you know, The better you know, How little you know

    “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

    Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

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    • #3
      Originally posted by H80N View Post
      These guys at NETWELDING claim to have a device that cures this problem..

      http://www.netwelding.com/Shielding_...l_Download.pdf

      I must say H80N, you are the man with a link for everything...
      Richard
      West coast of Florida

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      • #4
        Originally posted by Ltbadd View Post
        I must say H80N, you are the man with a link for everything...
        Those guys have been advertising on the net for many... many years...

        no idea if their product actually solves the problem...
        .

        *******************************************
        The more you know, The better you know, How little you know

        “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

        Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

        My Blue Stuff:
        Dynasty 350DX Tigrunner
        Dynasty 200DX
        Millermatic 350P w/25ft Alumapro & 30A
        Millermatic 200

        TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

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        • #5
          I would simply call your LWS and request a gas surge analysis. They more than likely will do this for you and for free - hoping you buy the appropriate equipment to solve the problem of course. YES you are using / paying for more gas than necessary. Victor and Harris both make products that will reduce the surge. Concoa makes a small orifice (similar to the one that is on the outlet side of your flowmeter) that you could install closer to the end of the line for cheaper. That will get rid of MOST of the surge, but not as much as the Victor or Harris product that has a regulator built in.

          Let us know how it goes!

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          • #6
            Physics

            Originally posted by iloveturbolag View Post
            So i decided to test the gas flow rate at the nozzle on some of out robotic welders (using this http://stores.ae-welding-industrial....tester-ck-gft/ ) and found that the flow was about 4-5 CFH less at the nozzle than the regulator. What I also found was there was a 2-3 second surge of gas that maxed out the flow meter, 50+CFH before dropping to the 35-40 range. There is a good bit of line between the regulator and the robot, about 25 feet, and its having an accumulator effect. Has anyone used one of those surge protectors with any results? Were there any downsides to this? Thanks.
            A surge of flow is hard to blame on the line between the regulator and the robot. If that line is acting as an accumulator, it would actually tend to smooth out the flow, not create a surge. The longer and larger the line, the greater the smoothing effect. A more likely explanation is that the regulator, like many regulators, leaks a bit. That means that the pressure in the line after the regulator is higher when there is no flow, than when the gas is flowing. A perfect regulator would have the same pressure, regardless of the flow rate, but perfection is not generally available.

            If you are using a fancy regulator with a flow meter, but no pressure gauge, then the meter is not going to show this effect. I suggest that you put a pressure gauge in the line between the regulator and the gas solenoid. What I think that what you will see is high pressure in the line when the gas is not flowing, and then an decrease in the pressure when gas is flowing. If the difference is extreme, I would replace the regulator, or perhaps rebuild it.

            I see this pressure effect in my own cheaper regulators, because I only have a pressure gauge and an orifice, not a true flow meter. I am looking at this as a physics problem; I am an engineer.
            Syncrowave 200, Millermatic 211, Victor torch, Propane forge....

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            • #7
              Raferguson - you may have to define "extreme difference" - my flowmeters have a static pressure (by design) of 50psi when there is no flow.
              "Beware of false knowledge; it is more dangerous than ignorance." ~George Bernard Shaw~

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              • #8
                The surges are real... We've done tests with balloons and flow rate testers at the end of the guns. Like the poster above said, flow meters deliver the flow rate at a preset pressure like 50 or 60PSI and use a small restricting orifice to regulate the flow. When the flow stops, the line between the regulator and the diffuser remains PRESSURIZED to whatever the regulator preset is. That said, when the next arc is initiated, all of the gas in the line between the regulator flow orifice and the diffuser is let out WITH NO RESTRICTION IN FLOW causing an initial surge. The length of the hose and hose diameter determine HOW MUCH gas is wasted in the surge. Another (preferably regulator) with a flow orifice as close to the diffuser as possible will cut down on the wasted gas in the surge.

                If you have a shop with quite a few arcs, or robots like the original poster's example, the wasted gas really adds up and you would quickly recover the cost of the extra equipment in gas savings.

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