Rubber Gasket Research Articles

Enhancement of Rubber Gasket Material for Pole Transformer

An acceleration life test for rubber gasket of pole transformer was performed. The Arrhenius method was applied as an accelerated degradation test. The failure mode was considered as an elongation, and the failure mechanism is counted as a heat. It is found that both the current material(NBR: Nitrile Butadiene Rubber) and recommended alternative material(HNBR: Hydrogenated Nitrile Butadiene Rubber) have the same Weibull distribution as a life characteristic. For life expectation 95% reliability level of characteristic life is used at using temperature. The test results for NBR and HNBR are 7.7 years and 28.0 years on of using temperature, respectively.

Estimated daily intake of phthalates in occupationally exposed groups

Improved analytical methods for measuring urinary phthalate metabolites have resulted in biomarker-based estimates of phthalate daily intake for the general population, but not for occupationally exposed groups. In 2003-2005, we recruited 156 workers from eight industries where materials containing diethyl phthalate (DEP), dibutyl phthalate (DBP), and/or di(2-ethylhexyl) phthalate (DEHP) were used as part of the worker's regular job duties. Phthalate metabolite concentrations measured in the workers' end-shift urine samples were used in a simple pharmacokinetic model to estimate phthalate daily intake. DEHP intake estimates based on three DEHP metabolites combined were 0.6-850 μg/kg/day, with the two highest geometric mean (GM) intakes in polyvinyl chloride (PVC) film manufacturing (17 μg/kg/day) and PVC compounding (12 μg/kg/day). All industries, except phthalate manufacturing, had some workers whose DEHP exposure exceeded the U.S. reference dose (RfD) of 20 μg/kg/day. A few workers also exceeded the DEHP European tolerable daily intake (TDI) of 50 μg/kg/day. DEP intake estimates were 0.5-170 μg/kg/day, with the highest GM in phthalate manufacturing (27 μg/kg/day). DBP intake estimates were 0.1-76 μg/kg/day, with the highest GMs in rubber gasket and in phthalate manufacturing (17 μg/kg/day, each). No DEP or DBP intake estimates exceeded their respective RfDs. The DBP TDI (10 μg/kg/day) was exceeded in three rubber industries and in phthalate manufacturing. These intake estimates are subject to several uncertainties; however, an occupational contribution to phthalate daily intake is clearly indicated in some industries.

Technical Notes and Tips: A Simple and Cost-Effective Method of Protecting Unburied K-Wire Ends

We propose a simple, effective and inexpensive method of protecting unburied Kirschner-wire ends for hand surgery. This technique involves bending the protruding wire 180° to form a loop, removing the rubber gasket from a 1-ml syringe and sliding this gasket over the wire loop in order to provide the required bulk and padding (Fig. 1). The gasket is then secured onto the loop with a 3/0 nylon suture. A less bulky dressing can then also be used on top of the protector. This technique prevents accidental injuries from sharp wire ends, and limits wire migration. Figure 1 The proposed technique of securing protruding K-wire ends

Testing the performance and compatibility of degummed soybean heating oil blends for use in residential furnaces

Degummed soybean heating oil (SHO) is a renewable energy resource, which can reduce dependence on foreign oil and create a new market for the soybean industry. This study demonstrated that SHO 20 (20% degummed soybean oil and 80% No. 2 fuel oil) is suitable for application in residential furnaces without modification. The tests conducted were: fuel properties, seal compatibility, long-term storage, and laboratory and field combustion. The physical property tests showed that the kinematic viscosity (0.0346 cm 2/s) and the pour point of SHO 20 (−30 °C) were within the ASTM requirement for No. 2 fuel oil; and the net heating value of SHO 20 (43.9 MJ/kg) was only 1–3% lower than the No. 2 fuel oil value (45.6 MJ/kg). Compatibility tests performed on the rubber seals and gasket materials (Nitrile and Viton) found in typical heating fuel pump systems indicated that the tensile strength and hardness values were not significantly affected by SHO blends when compared with No. 2 fuel oil. A long-term storage test revealed that there was no significant change in heat content and no visible stratification of SHO 20 blend during three months of storage. The pump pressure and the type of nozzle used affected the concentration of NO x , SO 2, and CO in the flue gas. As was expected, increasing the SHO fraction in the blend also reduced the SO 2 emission. The combustion of SHO 20 resulted in a higher flue gas temperature which increased the NO x emission than with No. 2 fuel oil.

Garlock purchases another UK company

Garlock (Great Britain) Ltd has acquired PTM (UK) Ltd, a rubber moulding and gasket fabrication company.

Cost-effective method for growing three-dimensional cell cultures in extracellular matrix extract

Three-dimensional (3-D) cell cultures are advantageous for modeling complex cellular behavior. A major issue with 3-D cultures grown in Engelbreth-Holm-Swarm (EHS) extracellular matrix extract, however, is the expense. We describe here a simple method using a rubber gasket laid over a coverslip, which provides sufficient 3-D area filled with a minimal amount of EHS, resulting in cost-effective 3-D cellular cultures that are easy to manipulate.

Different Effects of the Materials of Rubber Gasket on the Crevice Corrosion of Stainless Steel Metal

Different Effects of the Materials of Rubber Gasket on the Crevice Corrosion of Stainless Steel Metal

Urinary Phthalate Metabolite Concentrations among Workers in Selected Industries: A Pilot Biomonitoring Study

Phthalates are used as plasticizers and solvents in industrial, medical and consumer products; however, occupational exposure information is limited. We sought to obtain preliminary information on occupational exposures to diethyl phthalate (DEP), di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) by analyzing for their metabolites in urine samples collected from workers in a cross-section of industries. We also obtained data on metabolites of dimethyl phthalate (DMP), benzylbutyl phthalate (BzBP), di-isobutyl phthalate and di-isononyl phthalate. We recruited 156 workers in 2003-2005 from eight industry sectors. We assessed occupational contribution by comparing end-shift metabolite concentrations to the US general population. Evidence of occupational exposure to DEHP was strongest in polyvinyl chloride (PVC) film manufacturing, PVC compounding and rubber boot manufacturing where geometric mean (GM) end-shift concentrations of DEHP metabolites exceeded general population levels by 8-, 6- and 3-fold, respectively. Occupational exposure to DBP was most evident in rubber gasket, phthalate (raw material) and rubber hose manufacturing, with DBP metabolite concentrations exceeding general population levels by 26-, 25- and 10-fold, respectively, whereas DBP exposure in nail-only salons (manicurists) was only 2-fold higher than in the general population. Concentrations of DEP and DMP metabolites in phthalate manufacturing exceeded general population levels by 4- and >1000-fold, respectively. We also found instances where GM end-shift concentrations of some metabolites exceeded general population concentrations even when no workplace use was reported, e.g. BzBP in rubber hose and rubber boot manufacturing. In summary, using urinary metabolites, we successfully identified workplaces with likely occupational phthalate exposure. Additional work is needed to distinguish occupational from non-occupational sources in low-exposure workplaces.

대형 LNG선 주냉각기 해수라인의 부압현상 해석에 관한 연구

The heat exchangers in the ships have been changed from the conventional shell & tube type to the plate type due to some merits as a compactness, a high thermal efficiency and a light-weight. In recent, it is reported that the vacuum phenomena were occurred in the seawater outlet piping of a main central cooler (MCC) on the ships. From the viewpoints of a common sense, the vacuum pressure in the seawater piping is rare event and difficult to be convinced because the seawater is pumped into the piping by a seawater pump with a high discharge head. However, the occurrence of a vacuum pressure in the seawater line of an MCC is real situation and often gives a severe damage to a rubber gasket of an MCC with a plate type heat transfer area. In this study, we analyzed the vacuum pressure in the seawater line of an MCC by using the simpl Bernoulli's equation and found that the vacuum pressure in the seawater line of an MCC is inevitable untill the installation postion of an MCC is not lowered.

Effect of the surrounding aeration on microcapillary electrochemical cell experiments

In the microelectrochemical capillary cell technique a silicone rubber gasket is used to avoid any electrolyte leakage between the pulled glass capillary and the working electrode (the metallic tested material). In this study, it is demonstrated that the oxygen reduction reaction (ORR) is strongly affected by the use of the silicone rubber. Experiments under a surrounding argon gas shielding of the pulled capillary in contact with the metallic surface have been performed showing a large effect on the ORR. Considering the high permeation rate of oxygen through silicone, the decrease of the reaction rate observed experimentally was validated by FEM modelling assuming that the air/silicone/water interface at the tip can be described as an air/water interface.

Simplified Concrete Resistivity and Rapid Chloride Permeability Test Method

A simplified method of measuring concrete resistivity, as an index of permeability, has been developed that is similar to ASTM C1202 or the rapid chloride permeability test (RCPT). It is significantly faster and easier to perform, however In this test, cylinders 100 x 200 mm (4 x 8 in.) were cured in 100% relative humidity and tested using the same solutions, test cells, and rubber gaskets as specified in ASTM C1202. To eliminate the problem of the temperature rise of the sample during the test, only one current reading was taken (after 5 minutes) that could be used to calculate the concrete resistivity. Testing was conducted on various different concrete mixtures after 91 days of moist curing using both the new quicker method and the standard ASTM 0202 method. An empirical correlation between the new method and the standard method demonstrates the validity and promise of the new method.

Life time prediction of rubber gasket for fuel cell through its acid-aging characteristics

The present manuscript deals with the prediction of the lifetime of NBR compound based rubber gaskets for use as fuel cells. The material was investigated at 120, 140 and 160°C, with aging times from 3 to 600 h and increasing H2SO4 concentrations of 5, 6, 7 and 10 vol%. Both material and accelerated acid-heat aging tests were carried out to predict the useful life of the NBR rubber gasket for use as a fuel cell stack. To investigate the effects of acid-heat aging on the performance characteristics of the gaskets, the properties of the NBR rubber, such as crosslink density and elongation at break, were studied. The hardness of the NBR rubber was found to decrease with decreasing acid concentration at both 120 and 140°C, but at 160°C, the hardness of the NBR rubber increased abruptly in a very short time at different acid concentrations. The tensile strength and elongation at break were found to decrease with increases in both the H2SO4 concentration & temperature. The observed experimental results were evaluated using the Arrhenius equation.

Properties of films from corn zein reacted with glutaraldehyde

AbstractTo improve the mechanical properties of zein films, a commercial white zein was reacted in glacial acetic acid (HAc) with glutaraldehyde (GDA) from 0.5 to 16% by weight based on the weight of zein. Amounts of 4% or higher GDA‐modified zein, when cured in a closed system, generated a gel. That gel was insoluble in organic solvents known to solubilize zein. Zein solutions cast within a silicon rubber gasket sealed onto Teflon‐coated plates, when air dried, generated 0.7–0.9‐mm thick films. Those films from 8% GDA‐modified zein had a water vapor permeability of 5.9 × 10−8 g cm/Pa s m2. Overall, results indicate that our thicker films gave higher water vapor permeability than values reported in the literature. To achieve consistent and comparable results with differential scanning calorimetry (DSC) and dynamic mechanical analyses (DMA), film samples had to be heated to remove residual HAc. An increase in the glass transition temperatures for those films from GDA‐modification of zein, observed with both DSC and DMA, was attributed to the crosslinking of zein. Physical testing of tensile bars cut from GDA‐modified zein films showed minor enhancement of tensile strength, percent elongation, and Young's modulus in the 0.5% GDA‐modified zein films, which increased and leveled off with 4% or higher amounts of GDA for the modifications. When the 4 to 16% GDA results are averaged, the tensile strength for the modified zein films increased 1.8‐fold when compared with unmodified zein control films. On the same note, percent elongation showed a 1.8‐fold increase and Young's modulus showed a 1.5‐fold increase. GDA reaction with zein generated films with improved tensile strength, ductility, and stiffness when compared with respective zein control films that retained their integrity when subjected to either boiling water or extensive soaking. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Sealing Our Buried Lifelines

This article discusses the importance of rubber seals in pipes and appurtenances used in the waterworks industry. Efficient rubber seals prevent the loss of millions of gallons of potable water and prevent soils and groundwater contamination from sanitary sewers and other wastewater. The article discusses how ease of installation, dependability, long service life, and resistance to chemical attacks are factors that make bell‐and‐spigot push‐on gasket joints a common method of joining lengths of various pipe materials, including thermoplastics such as polyvinyl chloride (PVC) and high‐density polyethylene (HDPE), metallic pipes such as ductile iron and steel, and other materials such as concrete, fiberglass, and clay. The article provides an explanation of how rubber gaskets are designed to function and what the capabilities and limitations of elastomers are, thus allowing users to make sound decisions in the field.

Structural Integrity of Flat Silicon Panels for Nanosatellites: Modeling and Testing

Microsystem interfaces to the macroscopic surroundings and within the microsystems themselves are formidable challenges that this thesis makes an effort to overcome, specifically for enabling a spacecraft based entirely on microsystems. The NanoSpace-1 nanospacecraft is a full-fledged satellite design with mass below 10 kg. The high performance with respect to mass is enabled by a massive implementation of microsystem technology – the entire spacecraft structure is built from square silicon panels that allow for efficient microsystem integration. The panels comprise bonded silicon wafers, fitted with silicone rubber gaskets into aluminium frames. Each module of the spacecraft is added in a way that strengthens and stiffens the overall spacecraft structure. The structural integrity of the silicon module as a generic building block has been successfully proven. The basic design (silicon, silicone, aluminium) survived considerable mechanical loads, where the silicon material contributed significantly to the strength of the structural element. Structural modeling of the silicon building blocks enables rapid iterative design of e.g. spacecraft structures by the use of pertinent model simplifications. Other microsystem interfaces treats fluidic, thermal, and mechanical functions. First, solder sealing of microsystem cavities was demonstrated, using screen-printed solder and localized resistive heating in the microsystem interface. Second, a dismountable fluidic microsystem connector, using a ridged silicon membrane, intended for monopropellant thruster systems, was developed. Third, a thermally regulated microvalve for minute flows, made by a silicon ridge imprint in a stainless steel nipple, was investigated. Finally, particle filters for gas interfaces to microsystems, or between parts of fluidic microsystems, were made from sets of crossed v-grooves in the interface of a bonded silicon wafer stack. Filter manufacture, mass flow and pressure drop characterization, together with numeric modeling for filter design, was performed. All in all this reduces the weight and volume when microsystems are interfaced in their applications.

Corrosion of 304L stainless steel and chrome-plated drainage together with the ordinary black rubber and brass gaskets by stagnant solutions of sodium hypochlorite solutions

This paper presents the results of corrosion of 304L stainless steel sink, chrome-plated waste/drainage, brass and ordinary black rubber gaskets and putty by stagnant solutions of sodium hypochlorite. Three sets of experiments ( Case A, Case B and Case C) were performed. In each experiment four 500 ml beakers were labeled solution 1, solution 2, solution 3 and solution 4. Each beaker contained a solution of sodium hypochlorite, a chrome-plated drainage (with ordinary black rubber and brass gaskets), and a sample of the 304L stainless steel cut from a 304L stainless steel domestic sink. For the cases (Case A and Case C) where the chemical resistance of the putty was tested another set of four beakers labeled solution 1, solution 2, solution 3 and solution 4 were used for the putty samples. Two sets of four concentrations were used. The concentrations considered were: Case A: 50 ml of sodium hypochlorite solution per litre of water, 40 ml of sodium hypochlorite per litre of water, 30 ml of sodium hypochlorite per litre of water and 20 ml of sodium hypochlorite per litre of water. The other set of concentrations used were: Case B and C: 50 ml of sodium hypochlorite per 5 l of water, 40 ml of sodium hypochlorite per 5 l of water, 30 ml of sodium hypochlorite per 5 l of water and 20 ml of sodium hypochlorite per 5 l of water. In the Case B experiments the solutions in the beakers were replaced with freshly prepared ones every two days during the observation of the samples. All the experiments were run at room temperature for 30 days. Case A: The results show that highly concentrated stagnant solutions of sodium hypochlorite corrode the chrome-plated waste/drainage, the brass gasket and dissolve the ordinary black rubber and the putty used to hold the chrome-plated waste/drainage in place. Case B: The formation of black/blue deposit was noted on the threaded part of all the chrome-plated waste/drainage in each of the four beakers. The amount of deposits formed increased with the duration of experiment. The changing of the solution every two days increased the amount of deposits formed. The ordinary black rubber gaskets were chemically resistant to all the solutions. Case C: Peeling off of chrome plating (from inside the chrome-plated waste/drainage) was observed in all of the beakers during the initial stage of the experiment and black deposits appeared on the top surface of the chrome-plated waste/drainage. The ordinary black rubber gaskets were chemically resistant to all the solutions. The putty samples became slightly blackish in all the four solutions. The 304L stainless steel sink sample did not corrode in all the solutions.

Analyse et modélisation du comportement mécanique des conduites enterrées

As a consequence of their aging, the performance of buried pipes has become a major concern for the urban sewer systems managers. Improvement of both the pipe design and its installation conditions or a more efficient management requires first a comprehension of phenomena that lead to pipe deterioration. This research starts a new long-term and multidisciplinary topic where the study of the structural pipe degradation in relation with soil condition represents only one part of the whole extent. Within this context, our approach consists in first identifying such phenomena, then describing their effects on sewers. This PhD thesis is composed of three different parts. In the first part, a statistical analysis of failures affecting the Greater Lyon sewer network and the factors that are likely to make them appear is achieved in order to determine in what circumstances these failures occur. It is then possible to identify some of the mechanical processes that may generate the pipe deficiencies. It appears that the phenomena identified as having a major influence on the pipe behaviour are completely ignored by the current design standards. The second part is dedicated to the experimental characterization, via laboratory tests, of the mechanical behaviour of the most unknown part of the sewer pipe: the joint. A rheological model of its behaviour under three types of loading is developed so that it can be easily adapted to all kinds of joint with rubber gaskets. The last part regards a numerical 3D modelling of a trench and a pipe which includes all the major parameters having a significant influence on the pipe behaviour. A numerical representation of the joint is based on the lab test results, while the rest of the model is validated with the results from the literature. This numerical modelling is then used to investigate the influence of the soil variability within the trench, particularly focusing on the longitudinal pipe behaviour.

SHAP Potentiates the CD44-mediated Leukocyte Adhesion to the Hyaluronan Substratum

CD44-hyaluronan (HA) interaction is involved in diverse physiological and pathological processes. Regulation of interacting avidity is well studied on CD44 but rarely on HA. We discovered a unique covalent modification of HA with a protein, SHAP, that corresponds to the heavy chains of inter-alpha-trypsin inhibitor family molecules circulating in blood. Formation of the SHAP.HA complex is often associated with inflammation, a well known process involving the CD44-HA interaction. We therefore examined the effect of SHAP on the CD44-HA interaction-mediated lymphocyte adhesion. Under both static and flowing conditions, Hut78 cells (CD44-positive) and CD44-transfected Jurkat cells (originally CD44-negative) adhered preferentially to the immobilized SHAP.HA complex than to HA. The enhanced adhesion is exclusively mediated by the CD44-HA interaction, because it was inhibited by HA, but not IalphaI, and was completely abolished by pretreating the cells with anti-CD44 antibodies. SHAP appears to potentiate the interaction by increasing the avidity of HA to CD44 and altering their distribution on cell surfaces. Large amounts of the SHAP.HA complex accumulate in the hyperplastic synovium of rheumatoid arthritis patients. Leukocytes infiltrated to the synovium were strongly positive for HA, SHAP, and CD44 on their surfaces, suggesting a role for the adhesion-enhancing effect of SHAP in pathogenesis.

Long-term stress relaxation prediction for elastomers using the time–temperature superposition method

Increasingly, manufacturers need to provide warranties of over 10 years on rubber seals, gaskets and air-springs and warranties of between 20 and 30 years on O-rings for underground applications [Parker Hannifin Corp. Compression set vs. compression stress relaxation. vol. 1, No. 3; 2003.]. In order to expedite the development process, experimental concepts for accelerated forecasts of long-term relaxation are required. Previously the standard procedures have relied upon semi-quantitative methods which considered material behaviour at elevated temperatures. The objective of the work presented here is to develop precise forecasting procedures with the use of the time–temperature superposition principle, the Williams–Landel–Ferry (WLF) equation [J.D. Ferry. Viscoelastic properties of elastomers. 3rd ed.; 1980.] and the Arrhenius equation [ISO 11346. Rubber, vulcanised or thermoplastic – estimation of life-time and maximum temperature of use from an Arrhenius plot. 1997.].

High-Energy Density, Room-Temperature Carbonate Fuel Cell

4In this study, the viability of a high-energy density, low-power, room-temperature carbonate fuel cell has been investigated. A solid carbonate conducting electrolyte based an anion exchange membrane was used. The pH sensitivity of the membrane was addressed by converting it to the bicarbonate/carbonate form. The resistivity of the membranes was measured and chemical stability in methanol evaluated. Hydrogen, 1M, and pure methanol have been shown to be viable anode fuels. Carbon dioxide was observed at the anode exhaust when operating on hydrogen. Experimental Calcium hydroxide 99.5%, Fisher Scientific and methanol 99.9%, Fisher Scientific were used as-received or diluted with deionized DI water. 1-butyl-3-methylimidazolium tetrafluoroborate BMIBF4, 97%, Fluka was used as-received. Carbon dioxide, hydrogen, oxygen, and nitrogen gases were obtained from Air Products. Carbonate anion exchange membranes were prepared by soaking chloride containing AFN anion exchange membranes AFN, Somerset, New Jersey in aqueous solutions of sodium bicarbonate 99.9%, Fisher Scientific and sodium carbonate 99.5%, EMD Chemicals. Upon soaking in 1 M sodium carbonate, the membranes darkened from a light brown to near black and were found to be unusable as carbonate exchange membranes due to the high pH. The aqueous solution also changed from clear to yellow. In an attempt to prevent damage to the membranes, sodium bicarbonate was added to lower the pH of the solution resulting in green transparent membranes. The resulting membrane was measured to be 150 m thick. Fuel cells were constructed in two ways. The cells used for the hydrogen tests were formed by sandwiching the carbonate anion exchange membrane between two carbon electrodes coated on one side with platinum 20 wt % Pt/Vulcan XC-72 1m g/cm 2 Pt, ElectroChem, Inc. and hot-pressed together. The cells used in the methanol tests were constructed using epoxy to attach a rubber gasket with a hole of known area punched out to the electrode and membrane. An EG&G Princeton Applied Research model 263A potentiostat was used for the electrochemical measurements.