A catheter assembly includes a catheter hub defining an interior cavity and a catheter tube extending distally thereof. A rigid actuator extends proximally in the interior cavity and supports a seal member thereon. The seal member includes a central membrane, a distal portion, and a proximal portion. An hourglass shaped actuator cavity is formed in the distal portion and receives a barbed end of the actuator. The outer surface of the seal member is in partial circumferential engagement with the catheter hub to define an air path that allows fluid communication between areas of the interior cavity distal and proximal of the seal member. A punch tool is provided to form a tri-slit in the membrane of the seal member.
