Infusion systems (100) and related methods involving a catheter hub (102) and a male Luer connector (106) or a male closing cap (180) connectable to the catheter hub (102). The catheter hub (102) can be part of a catheter assembly (340) with a needle (342) and needle hub (344) and can include a valve (252), a valve opener (254), and a needle guard (366). The male Luer connector (106) can include a collar (108) that is fixed or rotatable relative to a male Luer tip (110). The collar (108) can have a conically shaped body. The catheter hub (102) can have a body having two centerlines that are angled to one another, or the male Luer connector (106) can have a body having two centerlines that are angled to another, or both the catheter hub (102) and the male Luer connector (106) each can have a body having two centerlines that are angled to one another. A support feature (146) can support the male Luer connector (106).
