IEC TS 62966-3-2021 pdf Mechanical structures for electrical and electronic equipment – Aisle containment for it cabinets – Part 3: Aspects of operational and personal safety

3.8 lead time time between the alarm signal and the release of the extinguishing medium 3.9 aspirating smoke detector ASD high-sensitivity detector, which consists of a central detection unit, that draws air through a system of pipes to detect smoke Note 1 to entry: The sampling chamber is based on a nephelometer, that detects the presence of smoke particles suspended in air by detecting the light scatterd by them in the chamber. In most cases aspirating smoke detectors require a fan unit to draw in a sample of air from the monitored area through its system of pipes. 3.10 delay device device that is part of a fire-fighting installation designed to ensure that flooding does not take place until the fire alarm devices have been activated and the specified lead time has expired 3.11 extinguishing gas concentration value for the concentration of extinguishing gas present in the atmosphere of the area being flooded expressed as % vol 3.12 qualified person defined as a person who, by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training and experience, has successfully demonstrated his/her ability to solve or resolve problems relating to the subject matter, the work, or the project 3.13 hazard area containment area plus any adjacent areas that will be flooded with the extinguishing gas 4 Safety requirements of an aisle containment General safety requirements 4.1 The mechanical design of an aisle containment, consisting of cabinets, cover panels, doors and roof panels shall have adequate design considerations to prevent hazards to people. The mechanical parts of the aisle containment shall be free of sharp edges, burrs, etc., that could present a safety hazard to personnel involved in their assembly, installation, use or maintenance. The aisle containment roof panels cannot be walked on, therefore their design and appearance shall make this obvious to personnel working in the data centre.