Glad you asked! You need to use them on both outside and inside for maximum effect. Use an input pipe (purple X) on the side the fluid comes from, and use an output pipe (yellow O) on the side the fluid goes to. Then you should set your fluid connection to transfer mode (in the correct direction) and transfer speed to the slowest you need. The slowest setting, 120 ticks per transfer, still gives you a throughput of 1250 units of fluid per second, which is more than enough for almost any application (an offshore pump produces only 1200 water per second).
