A321
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Distraction; Troubleshooting
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed
Aircraft
After climb out; we set up a restroom break. When I pulled my O2 mask out of the compartment; the hose blew off. I was able to reattach it; but while the First Officer was in the lavatory; the hose blew off again and this time; the retaining ferrule blew off and I was unable to find it. I wasn't able to reattach the hose and the oxygen was flowing out at full pressure. I turned off the crew supply and arranged a phone patch to maintenance operations. Upon conferring with maintenance; we agreed that we could not continue. We [advised ATC] and returned to our departure point where an overweight landing was made. If I had to guess; I'd say some pilots probably remove the mask incorrectly by pulling on the hose; rather than using the red release tabs. Whatever the cause; the hose was loose enough that when I went to put the mask on; the oxygen pressure blew the hose off its connection to the mask.
A321 Captain reported that an oxygen mask malfunction resulted in a diversion.