I was looking for a quick way to disconnect my gas hose and wished my 250EX had the standard 5/8" "B" Argon connector so I just added my own. I used the hole that was already present on the bottom of the welder to secure the gas solenoid with one screw which is good enough.
I used the PVC hose for the connection inside but used some crimp clamps I had but the clamps that came with the welder will work in a pinch. I used tie wraps to ensure the hose will not contact anything that will get hot or any screws.
I used the "B" Size 5/8" Right Hand Gas Fitting to 1/4" NPT Male, type AW-15A and got a 1/4" NPT with a barb that was the next size up from a 1/4" along with about 4, SS fender washers from Home Depot. I used a step drill and vacuumed up all the shavings.
I forgot to install the brass nut on the solenoid so I tie wrapped to hose inside so I don't loose it in the future if needed. I turned on the gas and then off and watched for leak down before reassembly...all good! A Little Teflon tape never hurts.
Now the hose connection is standard and I can add length, or a "Y" for a He tank if wanted in the future if needed.