Regulator/Flowmeter issue

admin

I recently purchased a Miller Syncrowave 200.I set it up in my shop and all was good.The next time I checked . . . the tank volume showed zero pressure in the tank!!But I was still able to dial 20 cfh on the flowmeter and lay down some welds.Is the one gauge broken?  Or can the tank have leaked down low enough to read zero but still have enough left for approx. 15 minutes of welding?I can't decide if I should be pissed that I just had a full tank of Argon leak out . . . . or I should just be irritated that I need to swap out the one gauge.
Reply:The gauge may be bad, but I'd check some other potential causes before replacing it.  Your should be able to get near rated flow until the high side pressure approaches the low side pressure.  The high side gauge graduations may be so large or actually start above the required low side pressure, to the tank appears to be empty, but you still get flow.  The regulator diaphragm could be leaking. The tank valve stem seals could also be leaking.  My brand new argon tank was delivered with a leak at the threaded connection of the valve to the tank.  Take the tank to your gas supplier and ask them to refill the tank and leak check it.  Mine LWS filled and fixed it for free after I lost the second tank full.   If it's not leaking after refill, take it home, connect it to welder, open valve and set flow, and then leak check all connections and fittings with soap-water solution.  The tank valve should be full open in use (back-seated), and full closed when not in use.    Also, if you leave tank valve open and regulator set and then shut off the welder, the solenoid valve in the welder is the only barrier to prevent leakage.  I just lost most of small tank of Tri-Mix gas this way on my Lincoln SP-135.TeddCoHTP Microcut 400 & Invertig 160DC  Smith Dual Guard MD-510 OA Rig  Lincoln SP135+  Hobart Stickmate LX 235/160