Iris valves - GIFs

[Jon]

I still don't fully understand the use cases for iris valves. In what applications do you need that precise control over fluid flow? Can the valves even close 100%? Are they typically used in conjunction with gate valves, so that the gate valve acts as an isolating valve, and then the iris valve controls the flow precisely?

However, they play prominently in science fiction movies, and their operation is aesthetically pleasing.

Here's a nice GIF of an iris valve opening.



And here's an iris valve opening on a trash can. Not exactly of critical use to society, but still cool.