Interesting to see the Y bottle i rent holds 5m^3 = 8 hours at 10lpm
So if a W is another 11 hours and only costs £4 more for a refill and £7 extra a year to rent...it looks like i need to move up a size.
Why not check out Air Products new cylinder half the size of the traditional W bottles but the same capacity.
Even has its own gauge and a fast fit connector.