A discharge assembly used with a fire suppression delivery system comprises a nozzle having an outer nozzle surface and inlet and discharge ends. The inlet end receives fire suppression agent and the discharge end dispenses fire suppression agent through an orifice. A blow-off cap has an open-ended cavity shaped to receive the discharge end of the nozzle and cover the orifice. The cavity includes an interior cap surface located in close proximity to the outer nozzle surface of the nozzle when the blow-off cap is mounted on the discharge end of the nozzle. A receptacle is formed in at least one of the outer nozzle surface of the nozzle and the interior cap surface of the blow-off cap. A retention element fits within the receptacle and engages the outer nozzle surface and interior cap surface, providing a predetermined amount of retention resistance to retain the blow-off cap on the nozzle.