Download or read book Performance of Elastomeric Components in Contact with Potable Water written by Thomas D. Rockaway and published by American Water Works Association. This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: For years the use of rubber gaskets, valves, hydrants, and fitting have been successfully widely used. However, recently an increase of elastomer failures has been noted. While the degradation appears to be coincident with a disinfectant change from chlorine to chloramines, other factors including temperature and pH and are believed to play roles. This research initiative was intended to clarify the factors that contribute to elastomer degradation and provide a quantitative method for predicting the performance and life expectancy of in-service elastomer components.

Download or read book Elastomeric Compounds Degradation and Associated Water Quality Concerns in Drinking Water Distribution Systems written by Raja Mohan Nagisetty and published by . This book was released on 2009 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, chloramines have preferentially been used in place of chlorine as disinfectant, as a result of increasing health concerns and USEPA regulations associated with disinfection by-products (DBPs). While the switch to chloramines generally has been beneficial, subsequent to this change, several utilities have reported problems with substantially higher rates of elastomeric compound failures in their water systems. To predict the long-term performance of elastomers within the water systems, accelerated degradation experiments were conducted at the combinations of three temperatures (23°C, 45°C and 70°C) and three chloramine concentrations (1-, 30-, and 60 mg/L concentrations) for natural rubber, neoprene rubber, ethylene propylene diene monomer (peroxide-cured), ethylene propylene diene monomer (sulfur-cured), styrene butadiene rubber and nitrile rubber. Elastomer degradation was characterized by mass change, volume change, breaking stress, breaking strain and hardness. Using a time-temperature superposition (TTS) principle the accelerated test results were 'doubly-shifted' (temperature and chloramine concentration) to service conditions to generate long-term performance curves. As TTS technique was not suitable for mass change data, aqueous chloramine diffusion into styrene butadiene rubber and natural rubber was analyzed using Fick's second law of diffusion to develop long-term mass intake prediction curves. Diffusion coefficients were calculated for 1 mg/L chloramine concentration at three temperatures (23, 45 and 70°C) and also for 23°C, at three chloramine concentrations (1, 30 and 60 mg/L). For 1 mg/L chloramine concentration, activation energy for diffusion of SBR and natural rubber were computed to be 51.13 kJ/mole and 77.29 kJ/mole, respectively. Also, concentration profiles were developed to understand the extent of penetration along the elastomer thickness over time and temperature. To investigate the water quality concerns as a result of accelerated elastomeric compounds degradation, accelerated degradation tests were conducted in aqueous chloramine solutions and then the solutions were analyzed for organic compounds using SPME-GC/MS. The water quality concerns that could arise because of these elastomeric compounds degradation were discussed with relevant literature review in this study. Considering the reports of elastomeric compounds failure in chloramines disinfectant water distribution systems, this study would provide better tools for water industry in managing the risks associated with elastomer failure.

Download or read book Distribution Water Quality Issues Related to New Development Or Low Usage written by Yakir J. Hasit and published by American Water Works Association. This book was released on 2006 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many water utilities deal with water quality problems in the distribution system due to low water usage. This study uncovers the many problems of low usage and reports on the variety of mitigation practices used by North American utilities. An included CD-ROM provides decision support software to help utilities systematically weigh the costs and benefits of a variety of best management practices (BMPs) for mitigating the water quality issues caused by low usage and thus cutting down on customer complaints and higher distribution costs.

Download or read book Elastomer Degradation in Water Utility Systems Via Loss of Carbon Black Observed with Atomic Force Microscopy written by Randolph Norman Schoenbaechler and published by . This book was released on 2007 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of monochloramines in the potable water supply industry has been selected as the disinfectant method of choice due to a longer term of effectiveness and less toxic by-products than the previous choice of chlorine. In spite of the benefits exhibited by the use of monochloramines much greater rates of elastomer degradation have been noted in the water industry. The modes of attack by monochloramines on the rubber parts are still poorly understood. A common ingredient in nearly all elastomer formulations is carbon black. In addition to its role as a filler material, carbon black is also known to add strength and durability to the elastomer. Degradation of average particle size showing that carbon black particles dissolve into the invasive liquid medium can be observed using phase images produced by atomic force microscopy. The nanoscale size of the carbon black particles makes the use of the AFM an ideal investigative tool. Elastomeric properties of the rubber coupons exhibit similar trends to the degradation of the carbon black material in the polymer matrix. Diffusion coefficients approximated by use of a simplified form of Fick's second law also shows a similar trend. Use of monochloramines as a disinfectant by the water supply industry produce fewer toxic by-products and maintain a longer useful potable water life than chlorine; however, rapid degradation of rubber parts will continue unless more suitable formulations can be found.

Download or read book NBS Special Publication written by and published by . This book was released on 1968 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plastics and Rubber International written by and published by . This book was released on 1979 with total page 918 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Performance Fillers 2007 written by and published by iSmithers Rapra Publishing. This book was released on 2007 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Kinetics of Sulfur and Peroxide Cured EPDM Rubber Aging in Chloraminated Water written by Jahnavi Valleru and published by . This book was released on 2006 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elastomer degradation when exposed to chloraminated potable water is dependent on a number of poorly understood factors. Temperature and chloramine concentration are both believed to play roles, however, they have not been adequately defined. In order to estimate the material performance and predict the service life of elastomeric parts, knowledge of degradation modes, rate constants of the aging process and their activation energies is useful. EPDM elastomers are used in numerous applications which require resistance to ozone attack and weather due to their stable, saturated polymer backbone structure. Accelerated aging experiments were conducted on both EPDM - S and EPDM - P at three concentration levels and temperatures. Tensile properties are used to study the extent of degradation through a 30-day aging period which are used to estimate the crosslink densities of both the materials. A rate expression is developed based on the rate of change in cross link densities. The rate constants are estimated and they are used to estimate the activation energies and frequency factors using an Arrhenius relationship.

Download or read book Management of Industrial Cleaning Technology and Processes written by John Durkee and published by Elsevier. This book was released on 2006-07-21 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: More stringent quality standards and environmental/safety regulations as well as new process and chemical technology have changed industrial cleaning from a "wet and wipe application to a valued and demanding process operation. This book will help cleaning operatives, designers of equipment, metal finishers, industrial chemists and decontaminators understand the value and demands required within the industrial cleaning process and an environment of continuing change.* Covers all aspects of modern cleaning technologies, helping readers to understand basics of cleaning, equipment used, techniques and possible changes to come within the industry.* Includes environmental regulations and the basis for modern cleaning technologies, ensuring the reader is up to date on cleaning chemicals and their affects.* Covers testing for cleanliness, ensuring cleaning operatives, technicians and end users understand how to achieve the demands required within the industrial cleaning process and an environment of continuing change.

Download or read book Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1979 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Building Technology Publications written by Center for Building Technology and published by . This book was released on 1979 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Publications written by United States. National Bureau of Standards and published by . This book was released on 1979 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Publications of the National Bureau of Standards 1978 Catalog written by United States. National Bureau of Standards and published by . This book was released on 1979 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Materials Performance written by and published by . This book was released on 1999-07 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Publications of the National Bureau of Standards Catalog written by United States. National Bureau of Standards and published by . This book was released on 1979 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Role of ANSI NSF Standard 61 and Third Party Certification in Providing Safe Drinking Water written by David A. Gregorka and published by . This book was released on 1990 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NSF Drinking Water Additives Program is the model for health effects evaluation of products and materials in contact with drinking water, including buried plastics pipe. One of the standards developed by the program, ANSI/NSF Standard 61 (Drinking Water System Components - Health Effects), covers the toxicology of indirect additives to drinking water for all types of potable water contact products and materials, including plastics pipe. For many years, NSF Standard 14 (Plastics Piping Components and Related Materials) has been the model toxicological and performance standard for plastics pipe, serving regulators, users, industry, and the public. Although it remains a viable standard, health effects in NSF Standard 14 are now addressed by reference to ANSI/NSF Standard 61.