I use a Clippard low pressure relief valve. It vents the gas if your CO2 tank dumps on you.
One way to avoid having your CO2 tank dumping is to get a good quality regulator. Even easier than that is to get it refilled once it gets down low(last couple of pounds).
You can also just turn it off if you don't have time to go get it refill when you see that it's low on gas.
I think the main problem with CO2 is most of us don't remember to check the gauges until it empty or there is a problem,lol