Yeah that would suck. I'd avoid pressurizing until that valve is closed!Very secure. The TC is rock solid and the jar is held on by its own ring band. I found a place called EcoJar and bought heavy duty stainless steel jar rings. I also use NorCal CO2 anti suck back lids so I was familiar with the fitment.
But whoa is me if that sucker did fall out and 11G of beer spills out....damnnn.