scholarly journals Chlorinated Water Induced Aging of Pipe Grade Polypropylene Random Copolymers

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 996 ◽  
Author(s):  
Joerg Fischer ◽  
Paul Freudenthaler ◽  
Reinhold Lang ◽  
Wolfgang Buchberger ◽  
Susan Mantell
Keyword(s):  
Fatigue Crack ◽  
Potable Water ◽  
Crystal Form ◽  
Hot Water ◽  
The Other ◽  
Random Copolymers ◽  
Waterborne Diseases ◽  
Water Pipes ◽  
Round Bar ◽  
Effect Of Chlorine

Polypropylene random copolymers (PP-R) are common materials for pressurized hot water pipes. In many pipe systems, potable water is disinfected by chlorine to prevent waterborne diseases. This paper deals with hot chlorinated water induced aging of two PP-R grades with varying morphology. One material had a conventional monoclinic α crystal form (PP-Rα), whereas the other was explicitly beta-nucleated resulting in a trigonal β crystal form with a fine spherulite structure (PP-Rβ). Micro-sized specimens with a thickness of 100 µm were used for aging experiments at 60 °C in chlorinated water with 5 mg/L free chlorine, and aging indicators were monitored for exposure times of up to 2000 h. On the other hand, superimposed mechanical-environmental tests were carried out by using cracked round bar specimens with a diameter of 14 mm to determine the fatigue crack growth (FCG) resistance of both PP-R grades at 60 °C in non-chlorinated and chlorinated water. PP-Rβ was found to outperform PP-Rα with an about 30% higher time-to-embrittlement value of 2000 h. Furthermore, PP-Rβ exhibited an enhanced FCG resistance in both non-chlorinated and chlorinated water. The effect of chlorine content on the deterioration of the FCG resistances was significantly more pronounced for PP-Rα.

scholarly journals Inhibition of scaling water of Tiznit region by "LEVALL®10".

2019 ◽  
Vol 8 (4) ◽  
pp. 283-289 ◽  
Author(s):  
Said Ben-aazza ◽  
Abdallah Hadfi ◽  
M'bark Belattar ◽  
Said Mohareb ◽  
Naima Hafid ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Water Treatment ◽  
Potable Water ◽  
The Other ◽  
Ecological Effect ◽  
Water Pipes ◽  
Other Hand ◽  
The One ◽  
New Generation ◽  
Carbonate Deposits

Combating the formation of calcium carbonate deposits in potable water pipes presents a challenge for water treatment systems, The use of inhibitors is one of the best techniques to prevent or delay the formation of these deposits. It is therefore essential to find a new generation of scale inhibitors, which is distinguished, on the one hand, by a better inhibiting effectiveness of calcium carbonate, and, on the other hand, by their ecological effect due to the respect of health and environment norms.

Structure Effects and Related Polymer Properties in Polybutadiene. I. Preparation and Characterization

1964 ◽  
Vol 37 (1) ◽  
pp. 169-185 ◽  
Author(s):  
M. Berger ◽  
D. J. Buckley
Keyword(s):  
Melting Temperature ◽  
Transition Probabilities ◽  
Benzene Solution ◽  
Amorphous Polymer ◽  
Crystal Form ◽  
The Other ◽  
Random Copolymers ◽  
Trans Content ◽  
X Ray ◽  
Melting Temperatures

Abstract Stereoregular polybutadienes, of both high trans and high cis contents, were isomerized to provide polymers of varying cis-trans content. These isomerizates were used to study structural effects on physical properties. The isomerizations were carried out under photosensitized conditions in benzene solution at 25° C. The reaction was controlled to deliver polymers over the range 0–95 per cent trans content. This range was selected to provide crystalline and semicrystalline polymers whose structures could be examined in terms of sequencing or blocking by established x-ray techniques. Isomer contents were measured accurately by infrared traces. Isomerizations reached an equilibrium of 77 per cent trans regardless of whether the reaction started with high trans or high cis polybutadienes. Intrinsic viscosity was found to increase regularly with trans content in conformity with the larger size of the trans unit. ηsp/c versus c relations were observed to give a complicated form and this subject was deferred for further study. Crystallinity decreased regularly with reduced trans content as the equilibrium of 77 per cent trans was approached. Continued isomerization at the point of equilibrium produced a completely amorphous polymer. The melting temperatures of the crystalline polymers were studied in detail by x-ray camera and counting techniques. These polymers exhibited two crystal forms. One form was stable up to 60° C and invariant with cis-trans content in the range 80–95 per cent trans. Below 80 per cent trans the melting point of this form decreased with further reduction in trans content. The melting temperature of the other crystal form was dependent on trans content and decreased with decreased trans content until it coincided with the melting temperature of the other form. The distributions of trans and cis units and sequences of them were calculated through construction of matrices of transition probabilities. Copolymer theory was invoked to calculate pseudo reactivity ratios for the trans and cis forms. The melting temperatures of the two crystals were found to follow the predicted curves for random copolymers, although not simultaneously. This behavior is discussed. The crystallinity of the isomerizates of high trans content was found to be similar to block copolymers in spite of the fact that the method of their preparation would require that they be characterized as random. The importance of a crystal transition in this case is stressed along with the general effects due to the amount and type of the noncrystallizable unit.

scholarly journals Potable Water Hygiene from the Stagnation of Water Point of View

2020 ◽  
Vol 64 (4) ◽  
pp. 328-335
Author(s):  
Jana Peráčková ◽  
Dominika Juhošová
Keyword(s):  
Water Quality ◽  
Water Supply ◽  
Stagnation Point ◽  
Potable Water ◽  
Point Of View ◽  
Hot Water ◽  
Factors Affecting ◽  
Water Pipes ◽  
Water Point ◽  
Definition Of

Potable and hygienically suitable water supply is important for both residential and commercial buildings. The contribution focuses on potable water hygiene and quality from the water stagnation point of view. Stagnation of water is very dangerous phenomena because it causes the change in water quality. Proper routing and arrangement of cold and hot water pipes can significantly reduce the risk of water stagnation. In the paper, the classical trunk-and-branch installation system with the hygienically more suitable alternatives are compared. The paper also provides the definition of potable water, basic factors affecting its quality and basic rules for its control.

scholarly journals 1227. Replacement and Rerouting of Pipes to Remediate Intractable Contamination of Potable Water Fixtures in a Pair of ICU Rooms

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S441-S441
Author(s):  
David M Carroll ◽  
Angela V Michelin ◽  
Melanie J Craig ◽  
Johnathan J Johnson ◽  
Jonathan N Yoo ◽  
...  
Keyword(s):  
Potable Water ◽  
Cold Water ◽  
Hot Water ◽  
Small Scale ◽  
Water Pipe ◽  
Water Heater ◽  
Water Pipes ◽  
Clinical Center ◽  
Immunosuppressed Patients ◽  
Hospital Construction

Abstract Background “Green” construction approaches may place hospitals at risk for long-term contamination of potable water, presenting hazards for immunosuppressed patients. Remediation may be needed to manage these unanticipated consequences. An indolent, 11-year cluster of Sphingomonas koreensis infections at the NIH Clinical Center was traced to potable water. During the investigation, 4 sinks in 2 ICU rooms were found to have intractable contamination. Despite replacement of sink fixtures, faucet swabs and water continued to grow S. koreensis, and mean free chlorine residual (FCR) from the sinks was 0.27 mg/L (goal > 0.5). We undertook a major project to replace and reroute sections of pipes leading to the sinks (Figures 1 and 2). Methods Hot and cold water pipes were removed from the sinks to the supply pipes and replaced. Pipes were rerouted so that hot and cold water supplying the sinks returned in a loop to the domestic hot water heater to eliminate 10-meter drop-down sections of dead-leg pipe. Automatic faucets were replaced with manual faucets. Faucet biofilm was swabbed and cultured monthly for S. koreensis. Environmental samples were cultured on sheep blood agar for 5 days. Yellow colonies were subcultured and identified by MALDI-TOF MS (Bruker). Results Demolition of the wall behind the sinks revealed hot and cold water piping containing stagnant water. Water pooled in cold water pipe had heavy growth of S. koreensis; water from the hot water pipe could not be collected. Hot and cold water FCR for the sinks after piping changes averaged 0.74 and 1.07 mg/L, respectively, compared with 0.27 mg/L simultaneously from automated faucets in unmodified ICU rooms. Faucet cultures were negative for S. koreensis after replumbing, and have remained negative for >6 months. Conclusion New hospital construction strategies appear to increase potable water contamination risks; novel remediation approaches are needed. Replacing contaminated water pipes and rerouting pipes to minimize stagnation eradicated longstanding contamination of 2 ICU sinks. Although the experiment was conducted on a small scale, it demonstrates that plumbing flaws that jeopardize patient safety can be corrected through multidisciplinary collaboration and creative plumbing strategies. Disclosures All authors: No reported disclosures.

Comparison of Stratification in a Water Tank and a PCM-Water Tank

2007 ◽  
Author(s):  
A. Castell ◽  
C. Sole´ ◽  
M. Medrano ◽  
M. Nogue´s ◽  
L. F. Cabeza
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Temperature Change ◽  
High Energy ◽  
Hot Water ◽  
The Other ◽  
High Energy Density ◽  
Water Tank ◽  
Charging And Discharging Processes ◽  
Change Material

Most of the storage systems available on the market use water as storage medium. Enhancing the storage performance is necessary to increase the performance of most systems. The stratification phenomenon is employed to improve the efficiency of storage tanks. Heat at an intermediate temperature, not high enough to heat up the top layer, can still be used to heat the lower, colder layers. There are a lot of parameters to study the stratification in a water tank such as the Mix Number and the Richardson Number among others. The idea studied here was to use these stratification parameters to compare two tanks with the same dimensions during charging and discharging processes. One of them is a traditional water tank and the other is a PCM-water (a water tank with a Phase Change Material). A PCM is good because it has high energy density if there is a small temperature change, since then the latent heat is much larger than the sensible heat. On the other hand, the temperature change in the top layer of a hot water store with stratification is usually small as it is held as close as possible at or above the temperature for usage. In the system studied the Phase Change Material is placed at the top of the tank, therefore the advantages of the stratification still remain. The aim of this work is to demonstrate that the use of PCM in the upper part of a water tank holds or improves the benefit of the stratification phenomenon.

LOW CYCLE FATIGUE BEHAVIOR OF Zn-22Al ALLOY IN SUPERPLASTIC REGION AND NON-SUPERPLASTIC REGION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5477-5482 ◽  
Author(s):  
ATSUMICHI KUSHIBE ◽  
TSUTOMU TANAKA ◽  
YORINOBU TAKIGAWA ◽  
KENJI HIGASHI
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Crack Tip ◽  
The Other ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Secondary Cracks

The crack propagation properties for ultrafine-grained Zn -22 wt % Al alloy during low cycle fatigue (LCF) in the superplastic region and the non-superplastic region were investigated and compared with the corresponding results for several other materials. With the Zn - 22 wt % Al alloy, it was possible to conduct LCF tests even at high strain amplitudes of more than ±5%, and the alloy appeared to exhibit a longer LCF lifetime than the other materials examined. The fatigue life is higher in the superplastic region than in the non-superplastic region. The rate of fatigue crack propagation in the superplastic region is lower than that in the other materials in the high J-integral range. In addition, the formation of cavities and crack branching were observed around a crack tip in the supereplastic region. We therefore conclude that the formation of cavities and secondary cracks as a result of the relaxation of stress concentration around the crack tip results in a reduction in the rate of fatigue crack propagation and results in a longer fatigue lifetime.

Effect of an additive TAB-1 on crystallization behaviors and tensile properties of iPB-1

CrystEngComm ◽  
2022 ◽  
Author(s):  
Jingqing Li ◽  
Ruo Bai ◽  
Shichun Jiang
Keyword(s):  
High Temperature ◽  
Tensile Properties ◽  
Hot Water ◽  
Water Pipes ◽  
Crystallization Behaviors

The excellent high temperature performances of isotactic polybutene-1 (iPB-1) in form I are demanded by many thermoplastic products like hot water pipes. However, as iPB-1 melt is a strong liquid...

Identifying and Reducing Scaling Problems in Solar Hot Water Systems

2003 ◽  
Vol 125 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Derek K. Baker ◽  
Gary C. Vliet
Keyword(s):  
Heat Exchanger ◽  
Potable Water ◽  
Hard Water ◽  
Water Systems ◽  
Hot Water ◽  
Tank Wall ◽  
Rate Model ◽  
Premature Failure ◽  
Water Side ◽  
Freeze Damage

In areas with hard water, scaling can reduce the reliability of solar hot water (SHW) systems. Common reliability problems associated with scaling are both mechanical (collector freeze damage, clogged passages, premature failure of pumps and valves) and thermal (efficiency degradation). A mechanistic and a mathematical scaling rate model are presented. Results from controlled experiments investigating the affect of key water chemistry and heat transfer parameters on the scaling rate are summarized. The implications of these results for designing SHW systems for scaling environments are discussed. Most importantly, indirect systems where the potable water side of the heat exchanger is integrated into the storage tank wall, such as in a wrap-around heat exchanger, are shown to be the most mechanically and thermally reliable systems for scaling environments. A new version of the software SolScale is discussed, which is intended to aid in the design of SHW systems to reduce scaling related reliability problems.

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