Flow meter

  1. John_d1974 Member

    Messages:
    31
    Location:
    Fife
    Stupid question I'm sure but do you really need a flow meter on your regulatlor? Surely the dial on the regulator is accurate enough?
     
  2. daleyd

    daleyd Member

    Messages:
    7,101
    Location:
    Wrexham, North Wales
    I always thought the dial on the reg outlet is a pressure gauge, not a flow meter? It will give a very approximate reading of flow but nothing like as accurate as a proper flow meter.
     
    Maker likes this.
  3. Hood

    Hood If it walks like a duck....

    Messages:
    12,581
    Location:
    Carnoustie, Scotland
    A flow meter allows you easier adjustment in my opinion but I don't even go by the flow on them and use a peashooter on the torch to get the flow right.
     
  4. Paul.

    Paul. Moderator Staff Member

    Messages:
    6,640
    Location:
    Northampton. UK
    Regulator dials are not that accurate for flow, I use flowmeters on my welders and they vary quite a bit from the dial, a peashooter is a cheap way of setting flow, to use it with a mig you'll need to temporarily flip the tension roller off to disable the wire feed.
    https://www.weldequip.com/gas-flow-tester.htm
     
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  5. Robert Mullins Member

    Messages:
    109
    Location:
    Salisbury, uk
    A peashooter is best, it shows how much gas flow is exiting the shroud/nozzle: keep your shroud clean, spatter build up can disrupt this flow, or cause the gas to swirl and induct non inert gases into the weld pool:
    Also, when your there, check your gas diffuser condition, it's purpose is to spin the shielding gas, create a vortex, so that as it is emitted from the shroud it 'hangs' together and is more efficient at shielding the weld pool, use only as much gas as you need, otherwise your paying to vent it into the atmosphere, I can assure you, that the suppliers do not mind
     
  6. Richiew Forum Supporter

    Messages:
    1,129
    Location:
    Teesside, England
    Sample of one but my peashooter flow meter and regulator dial match each other perfectly. I was hoping to save some gas with it but alas no.
     
  7. minimutly Member

    Messages:
    1,493
    Location:
    Pembrokeshire Wales
    Someone will have to explain how this peashooter on the torch meadures gas flow more accurately (better?) than a conventional rotameter or tapered flow gauge?
     
  8. The flow gauges on the regulator can be a bit out, the advantages of a pea shooter are they are more accurate plus they show you what is coming out of the end of the torch, if there is a big difference between the regulator and pea shooter readings this can be a good indication of blockages or leaks in the system
     
  9. minimutly Member

    Messages:
    1,493
    Location:
    Pembrokeshire Wales
    Blockages and leaks. You can't have one without the other surely. Still not convinced you can be sure its more accurate, but I expect if the two read the same, ergo, everything is good. Plus you don't have to look around behind you to check.
     
  10. You can have a blockage without a leak and vice versa quite easily, and as for the accuracy of what’s coming out of the torch, people can only tell you the facts, what you do with that information is totally up to you
     
  11. minimutly Member

    Messages:
    1,493
    Location:
    Pembrokeshire Wales
    Yes you can have a blockage without a leak, in which case the peashooter will read exactly the same as the bottle flowmeter.
    And where do these facts come from - are there specs for the accuracy of these things?
    You might think I'm being picky, but just saying something doesn't make it right, 20 odd years as an instrument technician makes me allways consider these questions. So far no answers.
     
  12. Hood

    Hood If it walks like a duck....

    Messages:
    12,581
    Location:
    Carnoustie, Scotland
    I will try and do some tests today but I have always found that I need more flow on the flow meter to get the desired output from the torch. Now I am talking Mig here with an 8m push pull gun. That in itself should make no difference but it seems to, possibly because there is more hose for the gas to have to travel through so possibly more pressure build up which then leads to more leaks along the way :dontknow:

    We will see what I can find. :D
     
  13. hotponyshoes Member

    Messages:
    3,377
    Location:
    Somerset. Uk
    After messing about with beer systems for a few years then I can confirm the length of the hose does make a difference due to the back pressure of what's already in the tube and the resistance from the tube itself.
    Obviously has a lot more effect on fluids than gas.
    If you swapped a 3m torch for an 8m one and did not change anything else I expect the reduction in gas flow would be noticeable by an experienced welder.
    That's presuming the flow on the 3m torch was bang on in the first place.

    I'm not sure that a pea shooter is inherently any more accurate than a regular gauge?
    A pea shooter looks much simpler to construct so could possibly be made more accurate for the same cost as a gauge. A pea shooter works on a precise size/weight ball and a couple of precise holes in something. A gauge is more like a mechanical watch

    I'm not sure how accurate you need to measure it for practical purposes anyway?
    If you have instructions/procedures that say the weld must be done at 14.4lpm then a calibrated pea shooter at the torch would be the way to go.

    I have a few jobs that I repeat now and again, I have notes on the welder settings and they include the flow rate. I use the pea shooter for convenience but my welders have gas purge buttons.
    If I had to disconnect the wire drive it might not be done the same way.
    At home I regularly swap the same bottle between the mig & tig and just give the regulator a turn up or down when I swap over. Every now and again I lean round the back and see if it is somewhere close.
    A few other lads use the welders for various jobs and it's quite common for somebody to start welding then shout 'turn the gas up a bit'.
    Nobody ever asks for it to be turned down!

    Some of my stuff is food grade so I will check the gas on that but I'm not good/confident enough to just jump into a job like that so after setting the welder/gas I will do a test piece first anyway. If i noticed the tungstan was a bit hot after the weld but the weld itself looked ok I would either increase the post flow or increase the gas. To be honest it would depend which way the welder was facing as to what I adjust!
     
  14. hotponyshoes Member

    Messages:
    3,377
    Location:
    Somerset. Uk
    I would say repetablitly is probably more important than absolute accuracy on a gauge anyway?
    (Unless you are working to a spec)

    If you know a certain job welds fine when whatever gauge you have read 8lpm and another job works at 12lpm you want the gas to come out at that rate whenever the gauge is reading that rate.
    It does not really matter to me if the gauge reads 8lpm but its coming out of the torch at 9.24lpm.
    As long as I know next time I want to weld the same thing I set the gauge to 8 and it works just as well as last time.

    There are so many other variables with welding. Any figures you look up are only going to be a starting point anyway. For a lot of jobs the initial settings or "+ a little bit" may well be more than good enough.

    If I was setting up a production line and using loads of gas I would be doing some test pieces/runs to see what the minimum flow rate would be to produce the desired finish and the regulators would be getting locked off at that.
     
  15. Hood

    Hood If it walks like a duck....

    Messages:
    12,581
    Location:
    Carnoustie, Scotland
    Ok, set the flow meter on the Tig, it has an 8m WP20, to 10lpm on the flow meter and tested with 3 different peashooters, all came out as close as I could say to 10lpm.
    Put an 8m WP18 torch on and that read the same on the pea shooters but the actual flow meter was now approx 11lpm. :dontknow: So if I adjusted the flow meter to read 10lpm then the peashooter would be under.

    I swapped the Tig to another flow meter and got exactly the same results.

    Mig next.
    Set flow to 20lpm with the peashooters and the flow meter was reading 24lpm approx, so quite a difference there. The flow meter however says for C02 so that could make a difference. I only have one flow meter here that can read over 14lpm so can't test out others.
    Next I put the Mig onto one of the smaller flow meters, set the flow meter to 10lpm and the peashooter was only 8lpm or so. That more or less ties in with the previous results, 2lpm difference for every 10lpm.


    So conclusion..

    I could probably just set the tig using the flow meter but better accuracy if I use the peashooter depending on torch.

    For Mig then I really need to use the peashooter if I want an accurate flow. In reality I can tell quite easily when the gas is a bit on the low side so I could turn it up. I can not really tell if it is too high though (within reason) so without adjusting as I do test welds to turn down until too low then turn up again slowly I could be using too much gas, a peashooter lets me know quickly if I am there or not.
    Obviously as a lot of my welding is outside then I sometimes have to turn up the flowrate but as said I soon know if it is too low so I can adjust without being wasteful in these situations.
     
    Munkul, hotponyshoes and Wallace like this.
  16. Very few of the gauges on regulators are spot on, some are better than others, restrictions can be caused by fittings, connections, solenoid valves, hoses in the torch etc, I am in no doubt you have superior knowledge and experience but I spend a good amount of time going around large fabricators measuring and monitoring actual flow rates using a calibrated digital flow meter at the gas shroud and what it says is coming out of the torch is very rarely what is indicated on the regulator for whatever reason, I guess I must just be unlucky
     
    Hood likes this.
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