You may want to consider piping the system with sweeps rather than elbows.
A sweep is a bend with a much larger radius and smoother inner surfaces
than an elbow. They are much less likely to clog and will reduce the air
flow far less than plumbing elbows.

Right

You will need to use adapters to change from the light drain piping
usually used to the schedule forty piping in which the sweeps are
available.

No adapters are required. The real BI vac piping is thinwall ~2" PVC and
there are 3 or 4 sizes of 90 o corners from 6" sweeps to tight 90's. All
the fitttings are standard BI couplings but it isn't compatible with any
other pipe size, PVC or ABS.

One strange thing I found: Kenmore/Sears makes (or has made & branded
Kenmore) BI vac systems but you can't buy one at Sears in the USA.

You CAN buy them in Canada..at least 5 different models/capacities and
they're hundreds cheaper than the other "name brands" sold in the US. A
friend from WA state went to Canada and got an upper end Kenmore model (
adjustable height (4) power head, bigger motor (3 stageIIRC) and it came
with an extra hose and spare set of tools just for the garage) for $ 300
less than a lower grade brand name in WA.

My wife is on her third one now and wouldn't be without one. I've installed
them all.