is not the case with passive devices that are generally only electrically monitored with no ability to determine if smoke can actually reach the detection element. ASD systems incorporate more than one level of alarm. This allows an ASD system to provide very early warning of an event, prompting investigation at the earliest smouldering stage of a fire when it is easily addressed. Other alarm levels may be configured to provide fire alarm inputs to fire systems as well as releasing suppression systems. ASD alarm sensitivities are configurable and can be programmed to levels ranging from thousands of times more sensitive than a conventional detector, to much less sensitive. The detectors work best in non-volatile environments. They can also be used in computer cabinets to alert users to the overheating of computer cables or individual computer components. Installation and placement ASDs are suitable for environments where a highly sensitive rapid smoke detection capability is required. This makes them suitable in clean rooms; areas which contain goods easily damaged by fire, such as tobacco, electronic rooms and highly flammable liquid and gases. Often, normal point detectors will recognise the danger too late, as smoke often does not reach the ceiling quickly enough for a fire to be detected in a timely fashion. As they can be easily hidden, pipe networks are suitable in environments where point detectors can be considered aesthetically displeasing, such as offices, apartments and hotel rooms. This factor also makes them suitable in locations where point detectors can be easily tampered with, such as in correctional facilities. Despite their high sensitivity ASDs can be used in dusty or dirty environments as long as correct design, installation and maintenance processes are followed. Most ASD products can accommodate a broad range of environments and applications – from both confined and open spaces to the cleanest or dirtiest environment, including telecomm, control rooms, waste treatment, mining and more. See also Carbon monoxide detector Heat detector Smoke detector References External links Detecting smoke in air ducts Three Wavelength Integrating Active fire protection Detectors Fire detection and alarm Smoke Aerosol measurement