True Alarm photoelectric sensors use a stable, pulsed LED light source and a silicon photodiode receiver to deliver consistent and accurate low power smoke sensing. Three user selectable sensitivities for special applications are available for each individual sensor, 0.2%, 0.5%, and 1% per foot. Standard sensitivity is 1.25% to 3.1% per foot. The fire alarm control panel runs an algorithm that can vary the sensitivity for normal applications between 1.25% and 3.1% per foot. Note: Fixed sensitivity settings higher than 1.0% per foot are not UL268 7th Edition compliant. The sensor head design provides 360° smoke entry for optimum response to smoke from any direction. Due to its photoelectric operation, air velocity is not normally a factor, except for impact on area smoke flow.