2Biz & others,
I am still waiting for the day where some of us put our "brains together" & do a computer simulation showing every scenario of "tricky" flow issues. In other words showing within transparent hoses flow to & from all our combined components that happens normally & when a check valve fails etc.
Maybe someday one of us with even low level skills of 3D Max or open source Blender etc. will volunteer. There are ton of tutorials on YouTube ... it actually would not have to look that pretty ... it just seems it would be a better way of showing the internal what-evers when it comes to check valves.
No no no ... not me ... I am not a person totally "spaced out" on Virtual Reality.