Thanks for that. All good to know. I had wondered if bottle tests also test the reg as well, as that's obviously very important too. But it sounds from what you've said if the reg is going to fail then the burst discs in the bottle do their job. So as long as the bottle is looked after everything else should look after itself.The low and high describes there relative position, ie pre or post regulation.
If the physical tank is over pressurised / gets left in the sun and pressure increases etc the high side burst disk will rupture and vent the tank.
If the reg is supercharging, ie it needs a service and is outputting way over its design the low side will rupture.
Most regs also have cross drilled threads so if you somehow start to unthread a reg from a tank it will vent the tank before the reg could be possibly sent flying.
As I'm old I may be wrong but in the early years of air being used, it was all co2 before, not all regs had all the safety features but all regs marketed now will.
The energy involved in tanks is something to be given the utmost respect.
Treat the tank well, as above a tank cover is a great option.
If the reg is misbehaving have it serviced by a professional.
If the tank exhibits any damage have it checked professionally.
Never put any for of oil in the reg.
Never try to override any of the safety mechanisms.