Kidde ionisation smoke alarms with test kidde 9040lsb this ionisation smoke alarm from kidde has been designed with a host of excellent features including a testreset button which can be used to check the alarm operation ionisation sensing alarms may detect invisible fire particles associated with fast flaming fires sooner than photoelectric alarms photoelectric alarms may detect visible fire particles associated with slow smouldering fires sooner than ionisation alarms kidde 9040lsb