Central vac airflow
Not always. There are many factors that can effect central vacuum airflow such as the hose. Here's some baird meter readings from my Broan CV-40B for example these were taking pulling the hose right into the central vac
Broan 1 1/4 wire enforced: 0
Aerus wire enforced (unknown diameter larger than 1 1/4): 2
Crushproof 1 1/4: 2
Hanmi 1 3/8 crushproof: 4
The installation of the central vacuum can also effect it's airflow the length of the run, the diameter of the pipes, the number of turns in the pipe.
My central is fairly old and doesn't have the power of modern units i know a beam 225c will pull a 5.5 on that hanmi hose which rivals even my best canister, and that's their basic model.
