Need a new guage for my 75/25 tank

[woodlandfarms]

You would not believe what happened, whlie transferring my mig welder from the old cart to the new cart somehow the tank came loose from the old cart and fell over. I about plotzed. My hands were full with the mig welder, and I was sure the tank was secure but something caused it not to be I guess.

Anyway, so the hose outlet connector snapped off. I guess I could tap it out, get a new cap, but I am thinking maybe I should just but on a new guage. Anyone have any suggestions? I am not sure if there are different types, but this is for my 75/25. It has 2 round guages. Nothing special (pretty cheap I am sure).

 

[MinnesotaDaveChalmers]

These HTP flow meters are $27 and work just fine:
HTP Argon CO2 Mig Tig Flow meter Regulator Welding Weld Flowmeter | eBay

 

[woodlandfarms]

This is the same guage I have for my Tig setup (it was part of a scratch start package). Is there a reason that these flow meters are better / more desired than the needle version?

 

[BukitCase]

Yeah, they actually measure FLOW - usually the needle types work OK, but they can only measure PRESSURE so there are assumptions used - like the restrictions in the gas line, torch, etc - if you change ANY of these, then the pressure DROPS in the entire flow path will likely NOT be the same as they WERE, so neither will the REAL flow be.

The float type is calibrated unto itself, because the flow tube is tapered very accurately and so is the WEIGHT of the float that's in it, so as long as that meter is flowing the same molecular weight of gas it was designed for, it doesn't matter what the REST of your flow path is doing; if the flow isn't actually at (say) 20 CFH, then the float won't read 20CFH. It will read whatever flow is actually going thru the meter.

IOW, you could have a PLUGGED gas hose downstream from your needle type gauge, and it will LIE to you and make you think your gas is OK (Til you look at the weld, that is)

In actual practice, they both work - it's just that the float type is more believable... Steve

 

[Shield Arc]

Is there a reason that these flow meters are better / more desired than the needle version?

When we built an outfall down river from the Bonneville dam. We used 1/16-inch dual shield to splice the 10-feet in diameter, 1-inch thick wall pipe. The welding crew were all ship yard welders from Portland. They insisted on flow meters.

 

[yomax4]

The regulator might be repairable but at the prices they go for these days is it worth it. I use flow meters but the flow gauges are fine too. Anywhere in the 15-35 cfh will get you welding so how accurate do you have to be. Also don't forget to install a fix'd orifice fitting on the back of your welder to help stop the woosh of wasted gas when you pull the trigger. Or you can buy a gas saver from Harris or an SLR100 from Victor but all you really need is an inert fitting with the tiny pin hole in the outlet as compared to the 1/4" passage on most regulators.

 

[woodlandfarms]

Well, I think I learned something new today. Argon and Co2 Flow differently. I got the guage everyone recommended and noticed one side said argon, the other Co2. Co2 had subtly different markings than the Argon side....

 

[dragoneggs]

Well, I think I learned something new today. Argon and Co2 Flow differently. I got the guage everyone recommended and noticed one side said argon, the other Co2. Co2 had subtly different markings than the Argon side....

Wondering also about flow gauges. I've only had dial gauges (C25) and know nothing of the higher tech gauges for Argon?

 

[BukitCase]

As I mentioned earlier in this thread, the float type flow gauges have a tapered tube - inside that tube is a CALIBRATED weight (some are just a "BB", but the weight and SHAPE, along with the taper of the tube, are what determine what the reading will be at any given flow. Those factors are chosen during design, along with the RANGE of flows for the particular application.

Float type flow meters will ONLY WORK ACCURATELY if the gas (or liquid) being measured is the SAME SPECIFIC GRAVITY that meter was designed for, because a HEAVIER gas/liquid will cause the float to rise higher in the tube at any given flow rate than a LIGHTER gas/liquid.

In actual practice, C25 gas (which is 75% Argon) is close enough to the same molecular weight as pure Argon not to change the reading by much - but pure CO2 is enough different to change the reading noticeably.

The dual scale on some float type gauges is there to compensate for different weight gases and is workable for welding purposes, but would NOT be used anywhere an EXACT reading was needed.

Bottom line - EITHER type gauge will be "close enough" for this purpose. The ONLY time the float type is better is if you get a blockage in your gas delivery system AFTER the gauge - under THOSE conditions, the needle gauge will LIE TO YOU, because it's only reading PRESSURE that's set by the regulator. You can see this for yourself if you have the needle type - squeeze the trigger on your MIG torch and set flow to 20 CFH, then RELEASE the trigger - your "flow" gauge will read MORE "flow" than it did while you were setting it. (Even though there's NO FLOW AT ALL when you're not welding)

This is because that type gauge is NOT reading FLOW, it's only reading the PRESSURE DROP across your entire "delivery system", including hoses and torch. If you were to disconnect the hose right where it comes out of the gauge, that gauge would read a LOT LESS and be flowing a LOT MORE gas, because that needle type gauge is NOT READING FLOW AT ALL.

If you were to do that SAME experiment with a FLOAT type flow gauge, the "BB" would be slammed against the TOP of the tube, because REAL FLOW is the ONLY thing a float will measure.

Pro's and cons - the float type flow meters will probably be more accurate, more useful in troubleshooting if you're having gas problems, BUT are more susceptible to damage if bumped - The needle type are OK for most usage, NOT quite as delicate, but WILL LIE to you under line blockage conditions.

Sorry this got so long-winded, I spent the last 35 years of my "indentured servitude" trying to explain to management why there are places where that $17 flow meter can NOT replace the $1700 one I spec'd (not exagerating)... Steve

 

[yomax4]

Some of the higher end flow meters have the tube with the float inside a square rotatable glass that has the calibration on each side for either Nitrogen, Argon. Co2 and Helium.( if you are using Inert gas) Yes they are very different in where the ball floats. Flow gauges which really can be very accurate like mentioned will not let you know when there is a leak. leaks should be infrequent though but they do happen. The flow gauges are very inexpensive to make so that's what you usually get with your welder. I have 2 mig units on my rack and use one tank with a Victor dual flow meter. Has 2 tubes with separate controls.