Affordable Compressor Water Filter
With the one I made of pipe I was unable to notice a difference regarding the inlet and outlet. I hooked it up both ways and couldn't determine if one way is better than another. It's currently hooked up with the bottom as inlet but I sandblasted on a humid day for two hours one way and switched for two hours and accumulated almost the exact same amounts of water in my manual drain water separator. The main thing is to get the air cooled down so it can't hold the water beyond your filter.