There are 3 classes to be considered when dealing with ASD systems.
Class A – Very High Sensitivity
This class can provide a very early warning when detecting smoke. These systems are relevant to high-risk locations, where staged responses to the multistage alarm conditions are clarified. This will guarantee minimum downtime of the protected locations in a fire-related incident.
Class B – Enhanced Sensitivity
Class B ASD systems are required to enhance sensitivity for purposes where additional confidence is mandatory for protecting a particular risk. The greater capability of such systems is used to counteract other risk factors in the protected area, such as extraordinarily high ceilings or significant air flows.
Class C – Normal Sensitivity
An ASD system that gives equal operation as standard point detection systems, meeting the requirements of the British Standards, EN 54-7.