Welding Tips and Tricks

I have four flowmeters with a helium scale on them. All of them hardly provide low flow accuracy below 20 CFH since the scales basically start at 10 CFH and the 20 CFH mark is around 1/2 inch from the bottom of a 6 inch scale. I want to know if I am at 5, 8, 12, 15 etc. Anyone know of a low flow scale range flowmeter providing great accuracy?

Hello Polobbie,

I faced the same issue a while back although I use Argon and not Helium. Welding flow meters are NOT laboratory instruments so I decided to employ a laboratory flow meter. I purchased a Dwyer 0 - 20 CFH meter from evilbay. The meter was calibrated for air and according to the documentation the adjustment factor for Argon was 0.8. Because Argon is denser than air, a lesser flow of Argon is needed to raise the float ball by a given amount. 10 CFH on the air scale corresponds to 8 CFH of Argon. I relabeled the scale for Argon as shown in the first picture.

I have only a flow regulator. As shown in the second picture I connected the output from the regulator to the input of the flow meter. The outlet of the flow meter goes to the welder. The valve shown next to the flow meter is a bypass. If I need more than the 16 CFH which the flow meter will provide I can open the bypass valve and set the flow based on the regulator.

All in all it has worked very well. I generally use a gas lens and a small cup for little bench top welding projects. The 8 - 16 CFH range is where I normally operate and I can set that with good precision using this setup.


Ken

p.s. For Helium the adjustment would be in the other direction as it is less dense than air. For example 10 CFH air on the flow meter might correspond with 14 CFH Helium or such. I do not have the calibration factor sheet handy at the moment. A laboratory type flow meter should come with its own sheet or it would be available on the vendor's web site.

Ken