Phak1, you're incorrect. This PCV valve is not a simple check valve
Your right, but I was trying to simplify it‘s operation, not knowing your degree of knowledge on the subject. The amount of air flow, at all different engine speeds and loads is critical to proper operation.
The PCV valve will also protect the engine in case of a backfire, which will force the PCV valve closed, so that the backfire flame can't reach the crankcase.
Here is a very simple illustration of a PCV valve that explains it’s operation.
