pcv valve

[panzerschrekk]

I have a question regarding the pcv valve in this how-to: http://www.mazdas247.com/forum/show...ow-to-MS3-Catch-Can-Install-with-tons-of-pics

Just to be 100% sure: this valve stops air coming from the green side from going to the orange side. But lets through the orange side to the green side?

 

[concept]

PCV valves are almost always check valves, in that they allow air flow in one direction, only. That direction is typically to the intake manifold.