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 | | A QUESTION OF SOUND | | | Saint-Gobain Pipelines | | 23/10/2006 | | | New acoustic test proves cast iron is the clear leader!
Following on from its thought provoking and successful `Burning Question' campaign which proved that, in tests with plastic-based systems, cast iron is the safest choice for above ground drainage systems in the event of fire, Saint-Gobain Pipelines raises another hot topic - the question of noise generated by above ground drainage systems.
The debate about the comparative sound qualities of various materials for soil, waste and rainwater systems has itself, at times, been fairly noisy. However, following independent testing to a new European standard BS EN 14366, recently introduced, Saint-Gobain Pipelines is aiming to silence the opposition with results offering what is described as definitive proof that cast iron is the quietest material.
'Hearing is Believing' comes hot on the heels of the damning evidence against the use of plastic-based drainage systems in the event of fire, in particular for multi-storey buildings because of the risk of fire spread down the building due to ineffective fire collars. The announcement of the acoustic test results launches a new campaign from Saint-Gobain to prove unequivocally that cast iron should form the material of choice for above ground systems in all public and commercial buildings.
Mike Rawlings of Saint-Gobain Pipelines says: 'The code of practice applied in the UK covering sound insulation and noise reduction for buildings, BS8233: 1999, suggests appropriate criteria and limits for different situations but the code doesn't cover the requirements for wastewater systems. This in turn has led to ambiguity in the claims made for relatively new materials about their sound performance when being compared to cast iron. The new European standard BS EN 14366: 2004, however, specifies a method for laboratory testing. Therefore, in the future all materials should test to the criteria laid down by this standard and the results of these tests will recognise a true comparison between materials. Saint-Gobain is the first to test to BS EN 14366 supported by Certification and emerges as the clear leader by a considerable margin.'
UK building regulations for noise in residential buildings call for an airborne sound insulation value of between 43 and 45dB for separating walls, floors and staircases. While this guidance is given for wall and floor types, little is offered again in the way of recommendation for waste, soil and rain water pipes within the fabric of the building. However, the evacuation of waste, soil and rain water naturally generates airborne noise passing through the pipe wall and system vibration coming from seals and supports.
BS8233:1999 provides guidance for minimum noise requirements by building type and methods of sound insulation to reduce levels.
Used in conjunction with the new standard BS EN 14366, which specifies methods for the laboratory measurement of airborne and structure-borne sound produced in wastewater and rainwater installations, a more accurate judgement can be made by the specifier as to which material is best suited for the application. The standard applies to pipes with natural ventilation, made of any standard material in commonly used diameters up to 150mm. Mike Rawlings continues: 'The European test method has been laid down by CEN/TC 126, a working group representing a cross section of materials.'
Saint-Gobain Pipelines submitted its Ensign cast iron system to be tested to the new standard in the independent IBP laboratory in Stuttgart, one of only two laboratories in Europe capable of undertaking such tests. When the Ensign cast iron system was fitted with acoustic dampeners to the standard ductile iron brackets, the noise level achieved 15dB at a flow rate of 4 litres per second generated through the system. Comparisons made against the new materials tested to the same criteria showed cast iron was up to 10dB quieter than HDPE and 5 to 6dB quieter than twin-walled PVC. To put this difference in perspective, it is Noise x 2, or in terms taken from a plaster board supplier: 'In order to increase sound insulation of a solid partition or wall by 4 to 5dB, the mass must be doubled.'
Independent tests carried out by acoustic engineers in Australia compared cast iron to PVC and stainless steel, resulting in cast iron being identified as some 13-14dB superior in acoustic qualities. So, cast iron really is king when it comes to sound attenuation.
Cost is an argument frequently raised in the cast iron vs the rest debate. However, the cast iron manufacturer counters the low-cost claims of plastics manufacturers with the fact that installed cast iron systems can compete on price. Mike Rawlings: 'When looking at the cost of a cast iron system, you need to factor in simplicity of installation and that there's no need for additional sound insulation, and the fact that cast iron is proven to be the best in the event of fire - again without additional protective measures. Other materials require more insulation so their costs rise.'
In addition, all other plastic-based and stainless steel materials require more brackets, a fact commonly identified in BS EN 12056-2 code of practice for gravity drainage, quoting cast iron one bracket every 3 metres, plastic materials one bracket every one metre and stainless steel one bracket every 2 metres.
The evidence from the Saint-Gobain tests carried out to the new standard BS EN 14366 at independent laboratories is conclusive that cast iron is the quietest material for soil, waste and rainwater systems.
Concludes Mike Rawlings: 'Cast iron is 5dB quieter than the best organic systems, 10dB quieter than HDPE and 13dB quieter than stainless steel. Hearing is most definitely believing!' | |
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