17 Combined thermal & acoustic lining It is standard practice to insulate ductwork internally for acoustic performance and externally for thermal efficiency. ArmaFlex materials can however meet both thermal and acoustic requirements through internally lining ductwork. By eliminating the need for an additional external insulation layer, this approach results in a significant reduction of material and labour. Eliminating acoustic bridging Wherever a direct physical connection exists, structure- borne sound, or vibration from the duct can pass to other parts of the building structure. So called ‘acoustic bridges’ are prevented by the introduction of resilient materials, like high density ArmaLoad sections between points of direct contact with the duct. Without using isolating and damping materials, in the worst cases all other acoustic treatment can be rendered ineffective as the noise follows the ‘path of least resistance’. Enclosure acoustics Compressors, pumps, air-conditioning units, heat pumps, generators and motors all generate large volumes of noise. Treating these pieces of equipment usingacousticenclosuresorcabinetsisahighlyeffective way of reducing the levels of noise experienced. When contained within any enclosure the noise associated with equipment exists in four distinct fields: • Internal airborne noise • External breakout noise • Enclosure wall vibration • Structure borne mounting vibration Lining enclosures Internal lining of enclosures prevents the build up of reverberant noise within the enclosure. This improves conditions inside the enclosure and also reduces the volume of energy able to break out from the enclosure. As such lining enclosures proves to be doubly effective – reducing noise both inside and immediately around it. Often the effect is even greater as lining materials also helps to restrict enclosure wall vibration. Selecting a sound absorbing lining Space may be restricted and so the need for good absorption at low thicknesses should be considered. Beyond acoustic performance alone, the health of any operative working in and around the enclosure must be considered, as must the potential that linings may come into contact with oils or other chemicals. Armacell manufactures a number of high performance sound absorbing materials suitable for internally lining enclosures. Due to the dust and fibre free nature of Armacell products, all of these materials are easily fitted in a single step without the need for additional facings and with no risk of fibre migration. Industrial pipework Heavy industrial pipework represents a major source of noise contamination on and around industrial sites and reducing this noise is a legal requirement in accordance with the ISO 15665 standard. The best way of preventing noise breakout is to apply a fully integrated, high performance, acoustic pipe insulation system – such as ArmaSound Industrial Systems. Aside from acoustic performance, this system also fulfils several roles as thermal insulation and provides a barrier against pipe corrosion. • Firstly, the use of a closed cell layer applied to the surface of the pipe minimises water ingress and the risk of corrosion under insulation (CUI) • Non-metallic coverings, such as Arma-Chek R, are available to avoid susceptibility to rust and/ or galvanic corrosion. Arma-Chek R is a tough, flexible elastomeric protective coating. The covering also provides a higher degree of compliance during installation to ensure better flexibility and improve sealing properties. The use of flexible elastomeric coverings also reduces low-frequency re-radiation effects that may be observed in practical application • The combination of a closed and open cell structure allows for a high degree of thermal insulation performance to be achieved. All components within ArmaSound Industrial Systems fulfil both acoustic and thermal roles, eliminating the redundancy associated with traditional approaches. Using an elastomeric covering reduces re-radiation effects resulting from transference of acoustic vibration into the outer ` surface • Additional acoustic benefits are realised around pipe supports and hangers through further reduction of structurally transmitted vibration. The combination of closed and open-cell technology, with an additional barrier covering, offers significant benefits for noise control engineers, specifiers and contractors In particular, high thermal and acoustic performance is combined with the reduced risk of under insulation and galvanic corrosion.