cylinder valve

Lately, a few Coltri Sub Cylinder valves, without any provision of Burst Disc on one side, is doing the rounds. How safe would it be to try these valves out? And what could have made Coltri Sub release a valve without the safety feature of a burst disc?

I’m in the uk and trying to find (another) Apeks manifold as well as o ring service kit for one I already have, but as I trawl the uk websites I’m noticing a sort of shortage, it’s annoying as the Apeks valves are really good quality in my opinion, and I’d rather stay with what I have, I do know...