Originally Posted by fritz1
I have a Mya that leaks at the purge valve at the weld it never purged worth a dam, if I exhale near the hose tip you can see the leak at the valve weld so my two Chinese are dust collectors
What Mya do you have? Every Mya I've come across does not have a welded purge valve. They're threaded into the chamber and sealed with an o-ring just like the hose ports are. Your o-ring may just be bad.
The bad purging however is because of the common chamber design. You can vastly improve it by making a purge tube out of brass or aluminum. You could also make a ghetto/temporary solution using a straw with one of those bendy necks.