Archive for March, 2013

Using Low Cost Seals can be a Long Term False Economy

Posted on: March 15th, 2013 by admin

Production processes utilising hazardous chemicals such as acids and amines, very often at elevated temperatures of 150°C or more, occur in a wide range of manufacturing industries including oil and gas, chemical, pharmaceutical and semiconductor. The combination of corrosive fluids and high temperatures can be particularly destructive for any sealing elements used in valves, pumps and other equipment forming part of a production process and associated pipework.

Interruptions to production processes through leaks and breakdowns resulting from seal failures can prove to be very costly, as well as having potential ramifications of causing environmental damage and jeopardising workforce safety.

The DuPont™ Kalrez® Spectrum™ 6380 perfluoroelastomer sealing parts are a non-black product specifically developed for chemical processes involving hot, aggressive amines. In addition, this product has an excellent overall chemical resistance and mechanical properties making it suitable for applications involving both static and dynamic sealing requirements. This cream coloured product is a prime choice for sealing operations with harsh aggressive chemicals, and it can withstand a maximum continuous service temperature of 225°C, with short-term excursions to higher temperatures also being permissible.

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Performance Enhancements for Mass Flow Controllers

Posted on: March 15th, 2013 by admin

Digital Mass Flow Controllers (MFC’s), as typically used in the semiconductor, chemical processing, food and pharmaceutical industries, are designed to both measure and control the flow of various gases and liquids. Applications also occur where MFC’s are used in analytical laboratories for High Pressure Liquid Chromatography. In many applications the gases and fluids are operating at modest temperatures up to 80°C, but can include aggressive media flows which necessitate the use of specialised chemical-resistant elastomer seals.

Most gas flow meters are equipped with seals made of DuPont™ Viton® fluoroelastomer. However MFC’s need O-ring seals and other custom parts that do not swell in the presence of more aggressive chemicals utilised within their wide range of industrial applications. The sealing specialist Dichtomatik Ltd, is an authorised distributor for the DuPont™ Kalrez® range of sealing products, designed to give extended performance when operating with the widest range of chemicals, even incorporating elevated temperature conditions. Tests undertaken with an MFC, fitted with DuPont™ Kalrez® Spectrum™ 6375 O-rings and custom parts, increased reliability of operation and the overall Meantime Between Failures (MTBF) of the equipment.

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High Performance Seals Extend DME Fuelled Transport Operations

Posted on: March 15th, 2013 by admin

Dimethyl ether (DME) burns much cleaner than diesel oils, and is also proving to be an economic and effective alternative fuel or fuel additive for use with gas turbines as well as petrol and diesel powered engines. However, the seals used on diesel engine injector tips must be specified to resist degradation where an aggressive alternative fuel such as DME is being used. Several elastomers and even fluoroelastomers (FKM’s) have been evaluated for use with DME powered engines, but operating temperatures above 100°C have led to seal degradation resulting in reduced engine performance and reliability.

However, the operation of diesel engines powered by DME fuel for commercial passenger transportation, with DuPont™ Kalrez® 6375 O-ring seals fitted to the fuel injectors, has achieved and maintained reliable engine performance without premature seal degradation. The broad chemical resistance of the Kalrez® parts, coupled with their high temperature compatibility enabled a significant improvement in engine performance as well as considerably extending useful operating life.

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‘O’ Rings Sweeten Sour Gas Processing

Posted on: March 15th, 2013 by admin

The Dupont™ Kalrez® Spectrum™ 6380 is a non-black sealing product that has been specifically developed for chemical processing applications involving hot and aggressive amines. Amine plants are operated throughout the world, typically in oil refineries and gas plants for the removal of H2S (hydrogen sulphide) from a product stream such as natural gas. New sources of oil and natural gas fields in the Middle East can incorporate up to 30% of H2S which is known as ‘sour gas’. However, the new, stricter environmental standards require ever decreasing contents of H2S, and the process of removing this contaminant from natural gas is commonly referred to as sweetening.

H2S is highly toxic and needs to be handled with care as it can cause embrittlement in metal equipment. Together with the harsh chemical environments and high temperatures that amine processes operate under, destructive swelling can occur with conventional elastomeric sealing components including fluoroelastomers (FKM) and perfluoroelastomers (FFKM). Loss of mechanical properties and extrusion of O-ring seals can result, leading to leakage and increased valve operating torques where seal face deformation has also occurred.

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