Sorry I've only just seen this post!

It's a good question. The bottle burst disc is a saftey device made to prevent over pressure from rupturing the bottle. As illustrated in your example, the disc will rupture and vent the entire bottle in the event of over pressure.

A pressure relief device will open whenever the pressure exceeds a set level. In an enclosed space this may be a safety benefit, however experience shows that burst discs rarely fail and normally only when the bottle pressure has been exceeded due to overfilling. Although unlikely, a pressure relief device could also freeze potentially leading to a hazardous situation. Whereas a burst disc has no moving parts so is less likely to fail in a combat environment and if so, safely.

Bottles should be handled wearing gloves to prevent the risk of burns especially as the bottles themselves can freeze.