Off the shelf Air valve required!

[Liquid]

I'm looking for a cheap valve designed to fit in a 1" diameter plastic or aluminium tube. An airflow designed to create a vacuum in a cup at one end of the pipe, and an air-moving fan is at the other end creating the pressure difference. The sorts of air velocities we are talking about are tens of metres per second.

This valve has to be driven by simple, small servos, and itself be compact. It does not have to have wonderful sealing properties or many complicated enhancements. I'd be looking at designing my own simple butterfly otherwise.

Thanks in advance for anyone who can give a fellow engineer a hand!