Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | AUGUST 2015 | 31 In the know Getting to grips with... mechanical seals Sealed with style Advances in modular component seal design have raised the industry standard by enabling confi gurable component seals to be built to order M echanical seals are found on most rotating equipment such as pumps and mixers to prevent the leakage of liquids and gases from escaping into the environment. It is best, therefore, to see the pump as only part of the system – and its performance and reliability is directly linked to that of the seal. A mechanical seal consists of two principal components. One component is stationary and the other rotates against it to achieve a seal. There are many types of seal, TOM BROADBENT, PROJECT MANAGER, AESSEAL ranging from simple single spring component designs to considerably more complex cartridge seal types. The design, arrangement and materials of construction are essentially determined by the pressure, temperature and speed of rotation and product being sealed. The component seal ranges available today incorporate seals to suit a wide range of applications in the water and wastewater sector. These seals are used in large volumes and, as the name suggests, are supplied as separate rotary and stationary assemblies for installation on site. What are component seals? Component seals consist of multiple parts including rotor, rotor face, stationary face, springs, O-rings, gaskets and seal gland. Each of these needs careful handling and considerable care and skill during installation. As a result, component seals incur greater potential for assembly errors, for example, incorrect spring setting (resulting in improperly loaded faces), dirt or grease contamination on sealing faces and damage to sealing components due to mishandling. All of these have the potential to result in premature, or immediate, failure of the seal. One of the major limitations with component seals historically, therefore, is that they were time consuming to install. Another consideration was that if conditions on site were not ideal or there was added time pressure to get equipment up and running it may have resulted in any one of these factors further compromising the seal's performance and the pump's reliability. Where are component seals used? Component seals are commonly used across a variety of industries; the type that is used depends on the pump type and its compatibility. For the water and wastewater sector, they are commonly used in sewage and water treatment applications. The most common type of component seal used in these applications are bellows-type seals. A selection of diff erent component seals

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