Gas solenoid vs Gas valve on MIGS

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I am wondering what the reason is behind installing a solenoid valve on higher end machines? Are they consider more reliable/leak proof to gas valves?  Are they normally installed inside the chassis or at the gun? (i'd imagine the gas delay would be detrimental if they're in the chassis, or are they also paired with a mechanical valve at the gun?)I guess the only way I see them as being helpful is in that they would deliver instantaneous flow when open (thus preventing weld contamination when starting the arc) but with the caveat of the solenoid being at the gun and not the chassis.  What am I missing?
Reply:The solenoid in mine is in the chassis and gas only flows when the trigger is pulled. I don't know much about all the other machines, just mine. I can't see any delay in the gas at arc start. I suppose if I laid the gun on the floor for a few minutes the gas might run out of the hose causing contamination on arc start. I've never tried that. I don't understand why anyone would need/want a mechanical valve. My solenoid valve will hold high side pressure for several days after the tank is shut off. I call that very reliable. Did I answer your question(s)? I also wasn't aware mine is a "high end" machine. I figure since it's 6-7 yrs old it's a dinosaur LOL.                                             MikeLast edited by mla2ofus; 09-17-2011 at 07:17 PM.Ol' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:In my experience, spool guns and some push-pull guns use a valve in the torch, whereas most 'standard' MIG guns use a cabinet mounted solenoid that opens with the trigger switch (of course, there are exceptions). Why, I can't say...
Reply:Originally Posted by mla2ofusThe solenoid in mine is in the chassis and gas only flows when the trigger is pulled. I don't know much about all the other machines, just mine. I can't see any delay in the gas at arc start. I suppose if I laid the gun on the floor for a few minutes the gas might run out of the hose causing contamination on arc start. I've never tried that. I don't understand why anyone would need/want a mechanical valve. My solenoid valve will hold high side pressure for several days after the tank is shut off. I call that very reliable. Did I answer your question(s)? I also wasn't aware mine is a "high end" machine. I figure since it's 6-7 yrs old it's a dinosaur LOL.                                             Mike
Reply:There is no delay as the hose from the solenoid to the gun is already full of gas so when the trigger is pulled the gas is already flowing out the nozzle.                                      MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Originally Posted by mla2ofusThere is no delay as the hose from the solenoid to the gun is already full of gas so when the trigger is pulled the gas is already flowing out the nozzle.                                      Mike
Reply:Originally Posted by chingonthat's what leads me to believe that there's probably an arc delay.  Gas has gotta travel thru the hose.  Might be less than half a second though.  I don't see how the hose could be full of gas if there's no valve upstream
Reply:Originally Posted by SandyIt isn't signifacantly lighter than air so it doesn't flow up out of the hose during short periods of the idle state. It is not signicantly heavier than air so it doesn't flow down out of the hose during short periods of the idle state. It does not evacualte the hose. It simply lays there waiting, and there is always a slight quick puff/burst which nearly instantly purges any tiny bit of air that might be near the end or in the nozzle.