Hi. I bought an old Union Carbide Linde regulator, which the seller told me was for oxygen. The regulator is one of the light duty types with the small 1.5" gauges and the blocky chrome body with the inlet going into the back of the regulator. I would like to use this regulator for argon. The inlet fitting going into the back looks like (from hand measurements) a 1/4" male NPT. I tried unscrewing it, and it is integral with the regulator. In other words, it holds in the valve spring.
I called up the local welding supply shop and they told me to bring it in. It seemed to be just a simple matter of putting the correct fitting, a CGA-580, on it, but they said that they had to check the threads. When I showed them the regulator, the fellow said that it would not work for argon, since the inlet gauge only goes up to 3000 psi. He said that oxygen and argon gauges must go up to 4000 psi, because the tanks can be filled to that pressure, and this little Linde gauge can "pop". He said that the gauge was probably for CO2, since a gauge that topped out at 3000 psi would be good for that. He then showed me an oxygen regulator they had for sale, and indeed, it went up to 4000 psi on the inlet gauge.
What is this little regulator useful for, if not argon and oxygen? Also, I looked for the 1/4" NPTF coupler required to connect to the standard CGA fitting with little success, but the breathing air and hydraulic shops carry them. Are these latter sources safe? They tend to have pressure ratings of 3000 psi.
Thanks, Eric