The folks at Harris should be the ones to talk to; nobody knows more about their equipment than they do.

Unofficially, it's my impression that a greater volume of He will pass through a given size orfice than Ar;the calibration would in that case be off, but, by a convenient coincidence, the amount of He required to shield is also greater by a similar amount. I have been told an Ar flowmeter will work with He, but the guy also swears he saw Elvis at the 7-11. I dunno what the heck would go on with a He/Ar mix except that if the threads fit you could get the gas out of the bottle..

I dont know the model 355, but you may be able to change an orfice- it looks like an adapter or tube between the regulator valve itself and the tank fitting- but why give it all that wear and tear? If its a super accurate meter you would defeat your purpose. Each time you break the assembly apart you risk getting debris past the filter.

So, I guess I left you where you came in, except to consider wear and tear and risk of damage each time you convert the meter, if conversion is indeed required.

regards
d

It should work fine with both mixes. As dee mentioned, the calibration will be off for the different mixes. But there won't be enough change for you to notice in your welding unless you are skating the edge with a minimum flow rate. I would suggest running practice beads to verify adequate shielding (no porosity) but everyone usually does that whenever they turn on the machine anyways.
CHGuilford

Thanks every buddy now I have more knowledge on this I really don’t care if its calibrated right just as long as it will work with both gasses and I have Emailed Harris this question to thanks