Thread: Regulator/Flowmeter question...

Hey guys, after not having access to one since I left the museum six years ago, I managed to score a nice old school square wave TIG machine (Hobart Tigwave 250 AC/DC) for a song. It's in great shape, everything works as it should, very happy camper here.

Now, friend and member pieces en regalia picked me up a regulator/flowmeter at an estate sale today for nearly nothing. I had to take it apart and get some green goo out of it before it would deliver gas, but it seems to be working properly now. It's an old Linde with all four scales on the flowmeter (CO2, 75/25, Ar and He), constant 50psi. Now here's the question... It's been a long time since I ran a TIG and I remember it starting with a hiss, but this almost seems like the regulator may be building excess pressure in the line, as there is a definite puff of gas at the torch when the valve opens.

The flow comes up to the proper pre-set level and then slowly drops back when the gas valve closes. Is this normal, or should I have the neighbor with the regulator rebuild shop have a look at it?

I quit useing flowmeters years ago and just use a 2 stage oxy regulater.

Much easier to rebuild

Sounds like your seat is deteriorated

"Sounds like your seat is deteriorated "

Hey, no need getting personal. lol

I have a torch and regulator rebuild shop literally 100yds from the house here. I'll give him a holler and see what he says.

I have some gas regulators, but want a flowmeter so I don't blow out a bottle of gas without knowing it.

Originally Posted by Mike C.

I have some gas regulators, but want a flowmeter so I don't blow out a bottle of gas without knowing it.

Me too.I got fed up with constant shouts of "need another bottle" always after 5pm.
Fitted a new regulator and flowmeter and the savings are dramatic.Too many welders are not happy unless they can hear the hiss a 100 yards away.

Yep i normally use a flow meter, set the regulator to give me desired max flow normally about 18 tops with flow meter fully open, then regulate flow meter from there, i hate the hiss! The lower the line pressure the beter the flow control and the longer the bottle lasts.

If you want to really make the most out of a bottle have a look at switching from a standard ceramic to a gas lens, makes a fair diffrence as you can run a bit less flow for the same amount of real world shielding. + a gas lens will help keep a air cooled torch running a fair bit cooler too :-)

Got a giggle out of the guy at work running 60cu ft/min because the "wind was blowing his arc". He was trying to patch up an oil soaked hydraulic tube. I tried to explain he was probably sucking air into the weld at that flowrate, but he knows a lot more about this than I do I guess. I'm not buying the gas there, so whatever.

I may have to experiment with your idea adama. I have a couple of inert gas regulators and could take the flowmeter off this set reg and install on one of them. Literally a three minute swap and can always switch back in another three minutes if I don't like it.

If you use a 2 stage reg the seat lasts longer and the presure stays constant throughout the life of the bottle

To make a 2 stage victor oxy reg into a flow meter all you need to do is change out the inlet nipple and add an orifaced outlet nipple and a gage calibrated to the size oriface (all redialy available at the welding store)

measuring pressure drop across a "hole" for want of a better word is not exactly precise. It is cheep and easy, but any error in the gauge and you can have a large flow difference. Equally any error in the orifice and you can have a significant error, yet still measure the pressure drop. Using a regulator to approach the flow then fine tune it with a flow meter just works better in my experience. The lower the pressure you can run the whole lot at the further your gas will go, especially if your doing a lot of short start stop type welding. Gotta remember every time you double pressure you double the volume of gas flowing, ie if your flowing 2 cubic feet a hour at 2 bar you actually flowing 4 cubic feet a hour when it expands at the nozzle back to atmospheric pressure (1 bar near enough for this example).

I do agree about a 2 stage regulator being nice, but in the real world i find i only have to tweek it a couple of times as the bottle gets low. A bottle will often last me a month or so, hence its not exactly a vast time cost issue. Add in im often changing flow based on nozzle and job and its pretty irrelivent. On a robotic welder though on solid production, yeah well worth while!!