Link above lead me to a number of good sites. I will stick to 15 lbs
because it was noted in a number of places that the Acet regulators
are designed to function at these low pressures.

The info on tank manifolds did indicate that free Acet at higher
pressures was common in a proper designed manifold but why mess around
if its not needed.

One thing for sure, 15 lbs is the max out of the regulator to the
torch. If it flows at substantial rates the gas is very unstable.