BS EN 50411-3-4:2019 pdf free.Fibre management systems and protective housings to be used in optical fibre communication systems – Product specifications.
1.2 Operating environment The tests selected, combined with the severity and duration, are representative of indoor and outside plants for above ground environments defined by EN IEC 61753-1: category C: Controlled (indoor) environment; -category A: Aerial (above ground) environment. 1.3 Reliability Whilst the anticipated service life expectancy of the product in this environment is 20 years, compliance with this document does not guarantee the reliability of the product. This can be predicted using a recognized reliability assessment programme.
1.4 Quality assurance Compliance with this document does not guarantee the manufacturing consistency of the product. This can be maintained using a recognized quality assurance programme.3.6 fibre management system FMS system to control, protect and store splices, connectors, passive optical components and fibres from incoming to outgoing cables Note 1 to entry: A fibre management system is intended for installation within a protective housing. Note 2 to entry: A fibre management systems is often called an “organiser”. 3.7 free breathing housing protective housing that allows a free exchange of air with the environment Note 1 to entry: Limited water ingress and/or limited dust ingress is possible. Free breathing housings are not intended for use in areas that are subject to flooding or water immersion. Free breathing closures are used in aerial environments for the interconnection of cables. Note 2 to entry: A free breathing closure may look like a sealed closure, but it is not designed to hold a varying overpressure or underpressure caused by temperature changes or atmospheric pressure changes.
3.8  microduct small, flexible lightweight tube with an outer diameter between 3 mm and 16 mm.3.12 passive optical component optical component or assembly which does not require any source of energy for its operation other than optical input signals, or controls the dynamic or static characteristics of optical signals using a source of energy Note 1 to entry: A passive optical component never generates an optical gain of signal power. Note 2 to entry: Examples include optical attenuators and passive branching devices.BS EN 50411-3-4 pdf download.