O-ring tube fittings require a smooth, flat seating surface. The seating surface must be perpendicular to the axis of the threads. Use this guide to install o-ring tube fittings. Simply follow the steps listed below:
1. Finger tighten the o-ring tube fitting into the port.
2. The "squeezing" effect on the o-ring can be felt during the last quarter (1/4) turn.
3. Lightly tighten with a wrench, and the tube fitting is installed.