Flowmeter vs regulator? Interesting results.

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Ok so I've been chasing a bad argon coverage issue on my tig welds. I had posted this thread when I first thought it was a contaminated tungsten electrode: Bad tungsten causing sparks and porosity on mild steel?After a lot of back and forth, I got some great results from new consumables (both new stubby collet body and new stubby gas lens body worked perfectly). However, in my search I found some info regarding how regulators tend to be less accurate than flow meters. I bought a cheap flow meter on Amazon (probably a big mistake here, but I'm cheap). It arrived today and I set out to do some testing with the primitive equipment I have on hand. I figured I'd post it here in case it's amusing to anyone or just to get your opinions on it. I wanted to test both devices to see how accurate they are. I set both of them to 25 scfh and measured the volume of gas they dispensed over a controlled period of time. I measured the gas with some super high tech equipment: balloons around the cup of the tig torch

. I pressed the pedal for 15 seconds and collected the gas in the balloons. Then I measured the diameter of the balloons and calculated the volumes. Turns out the flow meter is off by nearly 40%! I know this is not a great test, but the regulator was almost exactly correct.

      

      

So I know I totally could have bought one of the flow meters that you pop onto the cup of the torch. But if I get a cheap one from ebay, how do I know it's correct? I'll be back to square one. As ridiculous as this method is, it actually produced some interesting results lol. What do you guys think? Guess I'll return the crappy amazon flow meter.
Reply:While it would be nice if the cheap "stick it over the cup" flow meter was accurate, for your test it could give you an indication of the difference in volumes as long as it was consistent. If you keep on practicing TIG you will eventually recognize inadequate gas coverage and meter/gauge be damned you'll turn it up or learn to turn it down to what is sufficient. In your current experiment you need to have your balloons calibrated to ensure that one is not holding at higher pressure than the others. Always fun to experiment though.

---Meltedmetal
Reply:

Originally Posted by Meltedmetal

While it would be nice if the cheap "stick it over the cup" flow meter was accurate, for your test it could give you an indication of the difference in volumes as long as it was consistent. If you keep on practicing TIG you will eventually recognize inadequate gas coverage and meter/gauge be damned you'll turn it up or learn to turn it down to what is sufficient. In your current experiment you need to have your balloons calibrated to ensure that one is not holding at higher pressure than the others. Always fun to experiment though.


Reply:

Originally Posted by Meltedmetal

While it would be nice if the cheap "stick it over the cup" flow meter was accurate, for your test it could give you an indication of the difference in volumes as long as it was consistent. If you keep on practicing TIG you will eventually recognize inadequate gas coverage and meter/gauge be damned you'll turn it up or learn to turn it down to what is sufficient. In your current experiment you need to have your balloons calibrated to ensure that one is not holding at higher pressure than the others. Always fun to experiment though.


Reply:

Originally Posted by Oscar

Or simply run the experiment about 10x with each balloon to ensure some kind of consistency, and then swap the balloons with respect to the regulators and run another 10 trials.  Then get averages and compute final figures.
Reply:There's always a regulator whether it's a flow gauge or a flow meter. The set outlet pressures can vary greatly and these pressure differences could throw a loop in your experiment. A simple hand held gauge on the nozzle would tell the CFH.https://www.norco-inc.com/2381755/Pr...-32_Flowmeters
Reply:

Originally Posted by Mach_Zero

There's definitely a bunch of experimental error in this methodology. I could reduce the error significantly by using a large trash bag or much larger balloons. If I run the test for 60 seconds or greater, the timing error is reduced (I just don't want to waste that much argon!). But yeah I don't think the back-pressure from the balloons will have a significant effect on the test since the torch side of the regulator/flowmeter run at pretty high pressures. But with that being said, I doubt there's that much error. And even without the balloons, I was already skeptical of one of the devices because I could tell they were very different. Holding my hand up to the torch while it was reading 25scfh was very different for each device. But I just didn't know which device was wrong. And that's what prompted the balloon test lol.
Reply:Personally I wouldn't worry about initial numbers. Do some test welds. If a number 7 cup takes 18 cfh instead of the recommended 14 so be it. After you confirm what works use your test gauge to verify your cfh settings
Reply:Edit:As I see Dave has already mentioned,Your test will never match unless they are both the same pressure when not flowing gas. The initial dump from a 30 psi reg compared to one at 80 would be huge even at exact same verified flow rate settings.
Reply:So the question is which one is accurate?Weld like a "WELDOR", not a wel-"DERR"

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Reply:

Originally Posted by M J D

Personally I wouldn't worry about initial numbers. Do some test welds. If a number 7 cup takes 18 cfh instead of the recommended 14 so be it. After you confirm what works use your test gauge to verify your cfh settings
Reply:Also if I wanted to get crazy about it (which I have been known to do), I could also test at different flow rates and plot the error through the range of flow rates. Maybe the flow meter is accurate at 10-15scf and not so much at higher flow rates? But at this point I don't really care. I'm satisfied with knowing that the regulator is pretty close and I'll just keep using that. From there I can just adjust the flow depending on the results of the weld. But it's nice knowing when I set it to 15scfh, it's not at some completely different flow rate.
Reply:You will get further with your welding by welding practice rather than science experiments.
Reply:

Originally Posted by M J D

You will get further with your welding by welding practice rather than science experiments.
Reply:

Originally Posted by Mach_Zero

Turns out the flow meter is off by nearly 40%!
Reply:You probably considered this, but most of the cheap flow meters have more than one scale for different gases/mixes so you have to make sure you're using the correct one.  Also, some tell you to read off the bottom of the ball, and some the middle of the ball.  The wrong scale and the wrong spot on the ball could really throw off your numbers...just a thought.Check out my bench vise website:  http://mivise.comMiller Syncrowave 250DXMillermatic 350P with XR AlumaProMiller Regency 200 with 22A feeder and Spoolmatic 3Hobart Champion EliteEverlast PowerTig 210EXT
Reply:

Originally Posted by Mach_Zero

Well I guess that's why I'm a scientist and not a welder

But anyway I thought it was interesting and felt like maybe someone else would find it interesting too.
Reply:

Originally Posted by Mach_Zero

Well I guess that's why I'm a scientist and not a welder

But anyway I thought it was interesting and felt like maybe someone else would find it interesting too.
Reply:

Originally Posted by Kelvin

I doubt that.


Reply:

Originally Posted by Oscar

I had a feeling you were somewhat like me.  Just the fact that you whipped up that excel/spreadsheet told me you're familiar with data analysis and what not.  Just the fact that you know which variables even exist, can vary from reality, and need to be checked says that you will learn pretty quickly.  It's this kind of analysis that will eventually make you more self-aware of both the big-picture and the micro-details.  The vast majority of "help me" threads are a result of the beginning user not knowing what can even go wrong in the first place; the self-analysis is not there just yet.  They don't know what to check and how to check it.  I have a feeling that won't be you all that much.BTW, I'm the resident mad scientist AFAICT.


Reply:your experiment is interesting, but the data is completely flawed unless we know the regulators upstream of the flowmeters were both set at identical pressure.Since the US style is to integrate a pressure regulator into a flowmeter with a single pressure gauge indicating tank pressure, we have no way of knowing.You can have a higher flowrate at lower pressure and it may inflate a balloon less than a low flowrate at high pressure.Just saying, there's a variable which you have no control of, and also no way to measure it.Over here, the flowmeters are nearly always sold separately to the regulators - and you set them independently. It's better for tinkering, but worse for getting it wrong - it's too easy to crank the pressure up and end up with a whole load of start-up surge.

Originally Posted by Meltedmetal

If you keep on practicing TIG you will eventually recognize inadequate gas coverage and meter/gauge be damned you'll turn it up or learn to turn it down to what is sufficient.
Reply:Interesting experiment.This is the flow checker I use.

I use it to get repeatable results no matter what meter I'm using.If you get one, it'll also help you verify your testing methods for you - since you are looking at differences in flow.Nice thing is no wasted time wondering if the rate you wanted is what you are getting.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:

Originally Posted by Munkul

your experiment is interesting, but the data is completely flawed unless we know the regulators upstream of the flowmeters were both set at identical pressure.Since the US style is to integrate a pressure regulator into a flowmeter with a single pressure gauge indicating tank pressure, we have no way of knowing.You can have a higher flowrate at lower pressure and it may inflate a balloon less than a low flowrate at high pressure.Just saying, there's a variable which you have no control of, and also no way to measure it.Over here, the flowmeters are nearly always sold separately to the regulators - and you set them independently. It's better for tinkering, but worse for getting it wrong - it's too easy to crank the pressure up and end up with a whole load of start-up surge.
Reply:

Originally Posted by Mach_Zero

I'm having trouble understanding this. What does the upstream pressure have to do with the flowrate downstream? The purpose of these devices are to offer a specified flowrate at atmospheric pressure. They should all be calibrated to produce the desired flowrate no matter what their upstream pressure or internal design looks like.
Reply:

Originally Posted by G-ManBart

The Harris 355 flow meters that I put on my TIG welders are all set for 20PSI delivery pressure.  The Victor on my MIG is set for 25PSI delivery pressure.  I don't think they would work well at atmospheric pressure.

Originally Posted by Mach_Zero

Right, this one works at 50psig. But the torches are all at atmospheric. So their purpose is to ultimately deliver a flow rate at atmospheric, right? Unless I'm fundamentally misunderstanding something (which is completely likely lol). I was just trying to say that the balloon shouldn't create a significant enough backpressure to change the results.
Reply:

Originally Posted by 12V71

The balloon is not a reasonable comparison by any means, A ball type flowmeter reads flow passing the ball. A twin gauge flow meter reads pressure flowing though an orifice. Totally apples and oranges at the outlet. Any backpressure will null and void the results.
Reply:None of this matters. They are both flowmeters and if working properly and set to same flow then they will flow the same. If they don't then the simply aren't calibrated identically.  The issue is you starting from closed state to inflate balloon. You need to check the pressures of each reg/flow meter while they are capped up. If they are not the same it will not fill a balloon identically. A 30 psi would surely fill the balloon less than a 80 psi regulated flow meter.
Reply:

Originally Posted by danielplace

None of this matters. They are both flowmeters and if working properly and set to same flow then they will flow the same. If they don't then the simply aren't calibrated identically.
Reply:Sounds like you got it all figured out. With this analysis you should have no issues whatsoever 🤣.
Reply:

Originally Posted by M J D

Sounds like you got it all figured out. With this analysis you should have no issues whatsoever 藍.
Reply:

Originally Posted by Mach_Zero

I'm sorry but I respectfully diagree. A balloon creates negligible backpressure and these devices both operate at much higher pressures.1. Even without a balloon, when both are set to 25scfh, it is immediately apparent that the flow is different when listening to the flow at the torch and feeling the flow with my bare hand. The results of the test coincide with the feeling and sound of the flow. The flow meter set to 25scfh is barely audible, while the regulator set to 25scfh both feels and sounds like a lot more argon is rushing out of the nozzle. 2. The balloon causes negligible back pressure and these devices operate at greater than 50psig. As you can see, the balloons don't even inflate halfway. The pressure reached within the balloon is much less than 1psi.3. If these devices were that sensitive to the smallest bit of backpressure, then switching from a 12ft torch cable to a 25ft torch cable would drastically change the flow of the regulator/flowmeter. 4. The flow meter floats the steel ball depending on the flow achieved in the vertical flow gauge portion of the meter. If I apply significantly back pressure, it would cause the flow to decrease which would not float the ball as high. This didn't occur and I made sure the ball height was the same while the test was conducted.
Reply:

Originally Posted by 12V71

When you have been paid to do this stuff for 40 years get back to us.
Reply:

Originally Posted by Mach_Zero

Well instead of being dismissive, I'd appreciate it if you could explain to me why I'm wrong. I love learning about all this stuff so please point out what my misconceptions are.
Reply:

Originally Posted by Mach_Zero

Well instead of being dismissive, I'd appreciate it if you could explain to me why I'm wrong. I love learning about all this stuff so please point out what my misconceptions are.
Reply:

Originally Posted by 12V71

Your balloon test doesn't prove anything because of the backpressure. Get one of those "at the cup flowmeters" and prove it to yourself. Stop overthinking.
Reply:

Originally Posted by Mach_Zero

Right, this one works at 50psig. But the torches are all at atmospheric. So their purpose is to ultimately deliver a flow rate at atmospheric, right? Unless I'm fundamentally misunderstanding something (which is completely likely lol). I was just trying to say that the balloon shouldn't create a significant enough backpressure to change the results.
Reply:

Originally Posted by Mach_Zero

This matters precisely because it identified that the new device is not calibrated correctly or just not functioning properly. The flowmeter operates at 50psig and the two gauge regulator operates at 100psig. But this does not matter. The balloons will produce negligible backpressure and will not alter the flow. We are not measuring pressure here, we're measuring total volume and calculating the average flow for those 15 seconds. There is no way the balloon will have a significant enough pressure to change the flow of these regulators. I agree the specifics aren't too important. But the bottom line that I'm arguing with these tests is as follows: the new flowmeter does not produce flow consistent with the scale/gauge. That's it. It's wrong.
Reply:

Originally Posted by G-ManBart

I don't think the gas coming out of the end of the torch is at ambient pressure at all.  It has to be higher than ambient pressure to displace the air we don't want around the weld puddle.  I've used flow meters and regulators calibrated from 20PSI to 80PSI output and there is a very obvious difference at the torch end between those extremes.  I've used a number of Victor 2425 flow meters in the past (25PSI output) and always liked how they work.  The tech specs on them actually cover back pressure, and it doesn't even take a balloon to cause issues:https://www.esabna.com/us/en/product...flow-meter.cfm"A regulator equipped with a flow gauge is not accurate when a back pressure in excess of 2 PSIG exists at the outlet. Back pressure is caused by a restriction in the equipment downstream of the flow gauge. Metering valves, kinked hoses or even very long hoses are restrictions that can cause back pressure. In applications where back pressure in excess of 2 PSIG can be expected, a regulator equipped with a flow meter should be used. WARNING: High gas withdrawal rates may cause regulator freeze up and will require cylinder manifolding. Consult your gas supplier."
Reply:

Originally Posted by Mach_Zero

This is a good idea to have the same flow checker as a reference no matter what. Because even if it's wrong, you still have a reference and follow the same device each time. But this experiment was also to troubleshoot some issues that I was having. If you bought a regulator and you had to turn it up to 50scfh to get a decent weld, wouldn't you wonder if there was something wrong?At least as a beginner that doesn't have confidence, it's easy to wonder if I'm doing something wrong or if the meter is wrong. And that's where I believe the value of these tests lies. I was able to verify that this new flowmeter is completely off so I don't have to wonder if it's a technique issue. It's easy for an experienced tig welder to hear or feel the gas flow at the cup and know that it's too low or too high. But a beginner like me has no experience to reference whether it's too low or high. And all I have is the number on the regulator until I gain experience. And do you think it would be best for a beginner to learn on a damaged flowmeter that I have to turn it up to 50scfh to get 15scfh? I think that would be a terrible idea so that when I get a new machine I'll turn it up to 50scfh and wonder why the torch sounds like an air compressor blower lol.
Reply:Backpressure is vitally important to your results, as different flowmeters are calibrated at different downstream pressures.The best comparison will take backpressure totally out of the equation. A balloon provides backpressure, and worse - it's unknown, as balloons vary.As Dave said, a peashooter flowmeter at the torch will provide the best comparison, with absolutely zero unknowns. It doesn't matter how it's calibrated. It just matters that you use the same peashooter in the same way. Do that, and we'll accept your findings.Murphy's Golden Rule: Whoever has the gold, makes the rules.
Reply:

Originally Posted by MinnesotaDave

Your entire post is explaining why people should have a flow checker like the one I showed...
Reply:

Originally Posted by Kelvin

Way moar fun to argue about dopey Mythbusters so-called "methodologies"

than actually, like, do any welding ... get with the program, Dave!
Reply:

Originally Posted by MinnesotaDave

Oh sorry!  

I think the regulator was originally factory calibrated at a different longitude and latitude than the flowmeter.  I also believe the atmospheric pressure was different on those calibration days due to the massive thunderstorm that was blowing in out of the Rockies.The angle of the sun in relation to the calibration facilities at (high noon) was also different due to the latitude and the different months of the year.Once the balloon test is done under the same conditions, and in the same locations on the Earth, I think the results can probably be trusted.


Reply:Shoulda seen the guy on another forum who seemed to think that with a HAND micrometer, he could accurately measure to within +/- 0.1 micron (this is about the diameter of a single coronavirus virion)...
Reply:

Originally Posted by Kelvin

Shoulda seen the guy on another forum who seemed to think that with a HAND micrometer, he could accurately measure to within +/- 0.1 micron (this is about the diameter of a single coronavirus virion)...
Reply:Gas collection by water displacement might be more accurate and controllable:https://chem.libretexts.org/Bookshel...r_Displacement
Reply:Must have took the OP 3 days to even turn the machine on after figuring out if his electrical supply is compatible with the machine. Sorry but this has to be one of the most ridiculous threads ever posted where the OP isn't just being stubborn but trying to justify it. Curious why he didn't use a durometer to check if each balloon is the same hardness.
Reply:I can't believe barometric pressure and altitude weren't accounted for.
Reply:Interesting thread, I mean you guys ganging up on the op. My observation: balloons aren't calibrated or traceable.  I would have used condoms.  More reliability that way. Condoms should be from the same lot tho.  Also, you need a sample of at least three condoms.  More is better but that would be a waste of time in my opinion. Kinda like reading this postAnyway, carry on, no need to lock the thread. At least not on my account?I did use a condom with helium.  I thought I got scammed on clist day after so I filled a profilict (spell?) rubber with helium.  I don't remember the brand but the rubber floated for three days. Came down slowly after the. Helium is good.  It's not oxygen ated either. Another thing, I thought I had leaks plural, so I bought a pea shooter for tig torch end. No leaks found.  I feel much better because I have to buy gasses.