Contamination of Argon at the GTAW torch ?

[Capntom]

Our customer specification (RPS 184) states that we have to verify gas purity at the torch outlet. Either by O2 < 20ppm, Dew point < -40C or the subjective Titanium scratch plate.

We received a quote for a Vaisala Dew Point meter that we can install in-line upstream from the torch, but nothing "at the torch". How do other Aerospace or spec driven companies address this required?

 

[EdStainless]

I have seen the DP sensors mounted right at the torch-gas connection.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[unclesyd]

I once created a collection system for sampling at the torch tip. I took a side stream from the apparatus and it was analyzed for O2 and H2O for a time weighted average. Never found much of either.

Sampling at the torch tip is somewhat complicated as any effort to sample the gas creates a problem with stack type diffusion or aspiration.

You might want to look at this piece of equipment. Just make sure you don't have any leaks between the instrument and the torch.

http://huntingdonfusion.com/HFT/modules.php?name=Content&pa=showpage&pid=5

We made our own O2 scavenging system but used Dririte for the moisture aspect. We had this system on several welding stations but as stated above they had little to do.

http://www.drierite.com/default.cfm?goto_page=page4a.cfm