In Australia we call the tubes " siphon tubes " unfortunatly they all come stock as ridgid metal or plastic, but I am using a different approach ,some years back I experimented with liquid CO2 ( for fire extinguishment ) CO2 and N2O have some similar prpoerties ( liquidfied gas under pressure and similar cryogenic properties ,I needed the bottles to lay sideways ( horizontal) but with the siphon tubes also horizontal the best I could achieve was a 50% use of the liquid ( because the siphon tube at that point was out of the liquid so with some lateral thinking the flexable siphon tube was born , I have 2 types ,one requires the bottle to be "indexed " to the location of the valve outlet , the other finds its own level both work well , with my experiments on my nitrous bottles 10deg +ve of the horizontal is about optimum ,strange that no one has used this before ? lets see if my other "strange " ideas produce the fastest nitrous bike period come March
Hawkwind