Handling a real-world issue on the MX90

I was doing some practice dives on the MX last week. The planned dive was drop down to around 160 on scooters at Ship Rock on Catalina Island, then slowly spiral up around the pinnacle into the shallows for around a 60 minute dive (to match up with the boats required schedule)

We had practiced a bunch of skills in mCCR2, but up until that point, the only real issue I had experience was water in the exhale counterlungs and some leaks in the BOV

We descended through some cruddy (but still around 10 feet or so) vis.

As I hit about 110 feet, I pressed the O2 injector and ... the thing stuck on, constantly injecting O2 into the unit. There was a very audible sound of the O2 injecting at a decent rate (even through my 12MM hood) but it was not enough to seriously mess with my buoyancy (as a fully depressed button would do)

Thanks to the skills we had practiced, I was able to disconnect the O2 via the QC4 disconnect almost instantly, and exhale at least some of the bad gas from my nose.

I OK'd my buddies to let them know I was fine, and pushed some diulent through the unit to lower the PPO2.

Gently, I re-connected the O2, ready this time to disconnect instantly. I didn't hear anything, and things seemed fine. I signaled the team to proceed with the dive, thinking maybe some debris had gotten into the mechanism.

I deliberately did not inject any O2, and monitored my PPO2 constantly, as I knew that my 18/45 on its own could not deliver a PPO2 over 1.0 at the 120 depth we were at.

Over the next 60 seconds or so, the PPO2 slowly crept up again, so once more I disconnected and signaled my buddies.

At this point, I realized that I didn't have an effective signal for "My O2 has gone nuts" as one buddy attempted to help me reconnect the O2. I settled for signaling that my O2 bottle was broken with the traditional 1-finger salute.

I called the dive, and stayed on the loop up until around 50 feet where I went to the BOV and finished the ascent.

This ended up being mostly a non-issue, thanks to the practice we had done in class.

Of course, I could also have elected to feather on/off the O2 bottle as needed if this was a cave dive, or if we had some real deco to do (or needed to scooter home). Since we were close to the boat, that wasn't necessary.

On the boat, the button was pretty sticky, and I verified that my 50% bottle also had the same issue (removing the O2 bottle as the problem).

I managed to "fix" it on the boat, and it was fine for the next dive, but the next day I had a continual O2 creep that was manageable, but still cut our dive 10 mins or so short.

I serviced the injector and everything seemed perfectly fine. Clean as a whistle inside

Nick