Water Resistivity Measurements

Neutral Additives. In the course of our work, carbon black gave excellent, smooth surfaces. Samples containing 30% sulfur and 5% carbon black are unaltered after eight years. Originally, silicon grease, and later vacuum pump oil, were added as die-release agents. This was found to be unnecessary. However, as little as 1 wt % of such materials increases the tensile strength and water resistance measurably. 

If a pressure measuring device were run inside the capillary, an oil gradient would be measured in the oil column. A pressure discontinuity would be apparent across the interface (the difference being the capillary pressure), and a water gradient would be measured below the interface. If the device also measured resistivity, a contact would be determined at this interface, and would be described as the oil-water contact (OWC). Note that if oil and water pressure measurements alone were used to construct a pressure-depth plot, and the gradient intercept technigue was used to determine an interface, it is the free water level which would be determined, not the OWC. 

The method of measuting iasulation resistance varies with each type of device or product. The iasulation resistance of iasulated wire is the resistance between the conductor and the outside of the iasulation. When the iasulation is covered by a metallic sheath or braid the measurement is made between the conductor and the sheath. Insulated wire with no sheath is usuaUy immersed ia water and the resistance measured between the conductor and the water after the wire has been immersed for a specified period of time. 

For each specific appHcation of a mbber compound as an iasulating material, there is a minimum value of resistivity below which it does not function satisfactorily. In addition, iasulating compounds are required to withstand the effect of water, moist atmosphere, or heat without their resistivity values falling below a satisfactory level. Insulation resistance measurements frequently serve as useful control tests to detect impurities and manufactuting defects ia mbber products. 

For dynamic water resistance, the BaUy Penetrometer Test, lUP/10 (52) measures water penetration. 

For dynamic water resistance, the Maeser Test, ASTM D2099 (53) measures the number of flexes and water penetration. The flex imparted to the leather is a magnification of the flex given the vamp of a shoe ia actual wear. 

Wood chipboard is free from grain and is thus essentially isotropic in its behaviour. The mechanical properties are approximately the same as the average of the properties of the original wood measured along and across the grain. The water resistance of chipboard is poor but, being isotropic, it does not warp as long as it is able to swell freely in all directions. 

Short Normal Resistivity (after Anadriii). The short normal (SN) resistivity sub provides a real-time measurement of formation resistivity using a 16-in. electrode device suitable for formations drilled with water-base muds having a moderate salinity. A total gamma ray measurement is included with the resistivity measurement an annular bottomhole mud temperature sensor is optional. The short normal resistivity sub schematically shown in Figure 4-273 must be attached to the MWD telemetry tools and operates in the same conditions as the other sensors. 

Figure 4-298a shows the sketch of principle of the resistivity measurement in water-base mud. 

The term aggressive is often used to imply some approximately quantitative estimate of the likelihood of corrosion and depends on measuring factors such as soil water (resistivity), pH, redox potential, salt concentrations and bacterial populations in order to establish criteria for the prediction of corrosion rates . Similar measurements for predicting corrosion... 

It was concluded that dilatometry was the most reliable method and water absorption is difficult to determine. Both methods use appreciable quantities of film, which contain both D and / areas. Resistance measurements, however, can be carried out on small areas of film and the relative properties of D and / areas studied. 

Glass fibres present a particular problem. The water resistance of the base glass can of course the measured by a grain test, but this is unlikely to be representative of the performance of the final product. Generally, purely empirical methods are used to test the glass fibres in situ in a composite... 

The phenomenon of transmitting electrons through a body (an electric current). Usually associated with the measurement of electrical conductivity through water and measured in micro Siemens per centimeter (p,S/cm) or micromho per centimeter ( xmho/cm). 1 p,S/cm = 1 xmho/cm. The mho is equivalent to a reciprocal ohm (the unit of resistivity). 

Polarographic studies of organic compounds are very complicated. Many of the compounds behave as surfactants, most of them exhibit multiple-electron charge transfer, and very few are soluble in water. The measurement of the capacitance of the double layer, the cell resistance, and the impedance at the electrode/solution interface presents many difficulties. To examine the versatility of the FR polarographic technique, a few simple water-soluble compounds have been chosen for the study. The results obtained are somewhat exciting because the FR polarographic studies not only help in the elucidation of the mechanism of the reaction in different stages but also enable the determination of kinetic parameters for each step of reduction. 

DC techniques Include measurement of DC resistance, determination of polarization behavior, and measurement of polarization resistance. Coating resistance has been correlated with corrosion performance by a number of workers. As svunmarlzed by Leldhelser ( ), the results of several independent investigations suggest that coating resistance below about 10 ohm/cm Is associated with the formation of visible under-film corrosion. Parallel DC resistance measurements on thin film metal substrates have been used to study the deterioration of coated metals the technique successfully detected the effects of water after migration to the coating/metal interface (351. 

In order to avoid diffusion in the plgment/binder interface, in-terfaclal bonds between lx>th phases should be as water-resistant as possible. If permeability is taken as a measure, properly formulated barrier coatings may coiipare in corrosion protective efficiency with normal coatings, the thickness of vhlch is tvo or three times as high. 

In the case of Bi and T1 phases only very short reaction times (of the order of minutes) are possible because of the evaporation of Bi and Tl. This may be compensated by using excess Bi and T1 in the solution or by modification of the solvent (mixture of water and glycerol) that enhances the solubility of Bi and allows the use of less nitric acid in the solution. A more homogeneous deposition results in a better product after heat treatment. Figure 9 shows a typical resistivity measurement for a thallium film that has, however, a very weak critical current (50 A/cm2 at 77K). 

For each series of measurements about 50 g of solvent was transferred quantitatively in the dry box to the cell by pouring it into the dilution bulb this was the minimum amount required to fill the cell bulb. The cell was removed from the dry box, placed in the oil bath, and connected to the bridge. Time was allowed for the attainment of thermal equilibrium then at least three resistance measurements were made at five-min intervals, and the average value was calculated. The cell was removed from the bath and returned to the dry box. Dilute stock solution was quantitatively added to the cell by means of a weighing buret. The contents of the cell were carefully mixed, and the resistance of the solution was measured as before. The procedure just described was repeated several times with the dilute stock solution and then with the concentrated stock solution. About ten concentrations with a hundredfold range were obtained. A portion of the final solution in the cell (the most concentrated solution) was removed, and the infrared spectrum taken no absorption band indicative of traces of water was observed at 3600 cm-1. It was necessary to obtain the densities of... 

ELECTROLYTIC CONDUCTIVITY AND RESISTIVITY MEASUREMENTS. Industrial interest in the measurement of electrolytic conductivity (of which electrolytic resistivity is the reciprocal) arises chiefly from its usefulness as a measure of ion concentrations in water solutions. Also, by comparison with other analytical methods, this is relatively simple and inexpensive. 

It is important to understand the accelerating factors in RH cycling test. In-cell RH cycling tests are typically carried out by alternating an inert feed gas (N2) of controlled dew points. The water content of the membrane can be monitored by high-frequency cell resistance measurements. The result of the RH cycling test of a Nation based MEA cycled from 0 to 100% RH at 80°C is shown in Fig. 13. It can be seen that with the chosen cycling period ( 30 min)... 

The system does not display a glucose result for the first 10 h of operation to allow the equilibration of the sensor inside the body. The user is instructed to calibrate the sensor at hours 10, 12, 24, and 72, after insertion, by a blood glucose measurement. The blood glucose meter is built into the receiver, so the calibration is done automatically when a blood glucose measurement is made. After 5 days the user is instmcted to remove and dispose of the sensor support mount. The transmitter is reusable and contains replaceable batteries. The transmitter and mount are water resistant and can be worn during showers. The receiver is not water resistant because the receiver contains the open port for insertion of a blood glucose test strip. 

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