A cap assembly for a self-priming IV set valve includes a body portion that is configured to be removably connected to the IV set valve; a hydrophobic filter that is mounted to the body portion; and an actuator having a free end that is configured to either puncture, move or displace a valve element of the IV set valve. A fluid passageway is disposed either in or along the actuator. When the cap assembly is mounted to the IV set valve, the actuator either punctures, moves or displaces the valve element of the IV set valve such that air and liquid within the IV set valve can flow through the fluid passageway and onto the hydrophobic filter, whereupon the hydrophobic filter of the cap assembly prevents the passage of liquid through the hydrophobic filter while the hydrophobic filter permits the passage of air there-through and into the atmosphere.