Gas Flow

[uncrichie]

Hi all. Another gas question. I have a regulator on my argon bottle that has 2 gauges. One is the tank pressure (high pressure) the other gauge controlled by a black plastic knob is the adjustable flow to my equipment.

I have seen other regulators fixed at 30 psi with a high pressure gauge and an adjustable verticle flow tube.

What is the difference between these two type gauges and is one better than the other? Uncrichie.

[Broccoli1]

Like this one?

http://www.brweldingsupplies.com/brands/Victor/brand_details.cfm?product_id=917&ID=20

[Roger]

One type has what looks like 2 round pressure gages. One gage is the High Pressure gage and the other is the flow gage. Flow gage is a pressure gage calibrated to indicate units of flow through a specified size orifice downstream of pressure gage normally located in regulator outlet fitting. The orifice size is in fine print on flow gage face and should be stamped on regulator outlet fitting. Look into outlet fitting to see orifice. A flow gage will indicate a flow rate when solenoid valve is closed (no flow) that is higher than set flow rate when solenoid valve is open and gas is flowing. So down stream back pressure will cause inaccurate higher readings. This makes sense when you know flow gage is pressure gage adapted to indicate flow.
Flow gages are rugged and give accurate readings regardless of gage angle.
Higher regulator set pressure up stream of orifice pushes higher flow rate through down stream orifice.

Flow meter is supplied by fixed regulator pressure required by flow meter calibration. Flow rate is set by valve downstream of flow gage. Flow rate is indicated by weight (ball) being pushed up by gas flow in transparent tapered glass or plastic tube with flow rate scale. The tube ID is greater at top. When welders solenoid valve is closed stopping gas flow, flow gage indicates no flow. This type of flow meter must have plumb flow indicating tube to be accurate.

[uncrichie]

Thanks for the information fellas. Broccoli, thats the one I was trying to describe and Roger thanks for the great explanation. Is one type of regulator better than the other? Thanks, Uncrichie.

[PentaWelder]

The picture that is provided by Broccoli1 is a fine flow meter-regulator. What is to be understood is that the circular dial is measuring the PSI rating that is in the tank and the vertical meter is measuring the amount of gas in CFH (cubic feet per hour) that is being used. Think of this as PSI being the speed at which your garden hose is pushing the water out and CFH being the amount/volume of water being expelled. To weld either MIG, you should need no more than 25-35 CFH. Welding TIG, yo should need no more than 15-30 CFH.

[weldgault]

They should be the same, or close, if the inlet pressure is the same you are adjusting from> John

[uncrichie]

Thanks everyone for all the information. Being both types are close to being equal I'll keep what I have unless I run into unexpected $$$. Uncrichie.

[Roger]

Using what you have is good idea. MIG welding can handle broad range of flow rates from frugal just enough to get good welds unless very slight allusive breeze to just short of high flow turbulence is causing weld problems. TIG welding has narrower flow rate range between those 2 points. A good flow rate is any that gives good welds but does't waste gas. Precise flow rate is not real important.

[Rocky D]

The biggest advantage in a flow meter is that you can see the gas flowing, by the ball moving...this makes it easy to tell if you have a leak somewhere, too.

[uncrichie]

Thanks again fellas for the info, your the bestest. Uncrichie.