One-way flow is permitted by a "check valve", akin to elecronics' diode.
The 'aerator' of metal balls that looks like an airstone is sometimes called a "muffler", since by increasing the area through which the exhaust flows, and by calming its turbulence, the lous "Pshhh!" is quietened.
suggetion - do your machining on another planet, so you get no shavings near electronics or pneumatics.
