Let's say I have a pipe followed by a reduction and then another smaller diameter pipe continues. Using conservation of mass, the flow through the smaller diameter pipe will have higher velocity. If I apply Bernoulli to this system, while higher velocity, the smaller diameter pipe's flow has lower static pressure.
So this means if I have pressure gauges installed both before and after this reduction they would measure different pressures? And the pipe wall design should be different (eg. each side should take into account different pressure values)?