The patented geometry is very simple, yet L/H units are highly successful and applied world-wide to many in-line mixing problems in pipe sizes from 1' through 24'. The L/H unit is used to introduce a very small amount of a low viscosity additive into a much higher viscosity melt stream.
It can be shown that if 'F' is the additive fraction where F = 0.01 for 1% then the A/t value for the L/H unit is 8/p 2F. In other words if F = 0.01 or 1%, then A/t = 81. This is clearly a big improvement over the value of p we get for a simple T inlet.