Flow permeability test

Flow Permeability Test. A rough estimate of an equivalent mean pore size may be made by measuring the porosity (6) and permeability (J) of the membrane. Assuming laminar flow, the Hagen Poiseuille relationship may be modified for a porous membrane  

The porosity (e) of the membrane is the same as the void volume of the membrane and may be determined by measuring the difference between the wet and dry weights of the membrane. Since 

All the variables on the right side of equation (8) are experimentally measurable except for , the length of the pore. Obviously, is related to the thickness of the membrane by a tortuosity factor. The problem is that we cannot measure the tortuosity factor with any degree of certainty. 

Even the case of capillary-pore membranes where is only slightly larger than the thickness of the membrane, inertial losses, especially front-and-back-face losses, may be significant. 

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Radial flow permeability testing apparatus. (Reprinted from J. R Feser et al. Journal of Power Sources 162 (2006) 1226-1231. With permission from Elsevier.)... 

Underdrains are the most accurate in situ permeability testing devices because they measure exactly what comes out from the bottom of the liner. They are, however, slow to generate good data for low-permeability liners because they take a while to accumulate measurable flow. Also, underdrains must be put in during construction, so there are fewer underdrains in operation than there are other kinds of testing devices. They are highly recommended for new sites, however. 

Ruth et alS4-7) have made measurements on the flow in a filter cake and have concluded that the resistance is somewhat greater than that indicated by equation 7.1. It was assumed that part of the pore space is rendered ineffective for the flow of filtrate because of the adsorption of ions on the surface of the particles. This is not borne out by Grace18 or by Hoffing and Lockhart(9) who determined the relation between flowrate and pressure difference, both by means of permeability tests on a fixed bed and by filtration tests using suspensions of quartz and diatomaceous earth. 

To access the importance of Fg in Equation 53 and to determine how this quantity changes from non-dispersed flow to foam flow, a transient gas permeability test was performed and the results presented in Figure 11. In particular, drainage and imbibition tests were first conducted to reach a final drainage state with Ql being fixed at 0.53 pl/s. The measured permeability corresponded to the lower curve in Figure 11. Here again, the dependence on gas... 

Permeability A review of the permeability test method and application of the results (critical flow rate). 

Determining air permeability of a fabric is another standard test used in the quality analysis of textiles. Measuring air flow through a specific area of the fabric at standardized differential pressure is a good indicator of downproofness. In general, the lower the air permeability of the fabric tested, the less likely it is that feathers and down will penetrate it. However, these test results are not necessarily conclusive. Some fabrics may fail the air permeability test but pass the physical downproof test and vice versa. 

Figure 6. SEM image showing a typical membrane surface (80wt%Pd) after hydrogen permeability testing over the 350 to OOO C range under flowing 1000 ppm H S in H2.

Importantly, fracture permeabilities may either reduce or increase, in surprising ways, depending on the paths of stress or chemical potential. We illustrate this behaviour through observations during flow-through tests on samples of varied rock types. These include a fractured porous medium (Berea sandstone), and fractures in both silicic (Arkansas novaculite) [Polak et al., 2003 Yasuhara et al., 2004] and carbonate rocks (Bellefonte Limestone) [Polak et al., 2(X)4]. 

Figure 3. Change in differential pressure versus time for a flow-though test on Berea sandstone. Sample temperature incremented from 20°C to 120°C and then returned to 20°C. Matrix permeability 500 mD. [Courtesy A.B. Polak].

The air flow permeability of cellular materials can be correlated with cell structure. A standard method of measuring air flow of flexible materials is given in ISO 4638 [88], based on detecting the pressure drop across a test piece through which air is passed under controlled conditions.. A relatively. simple quality control method is given in ISO 7231 [89], where the flow rate is measured at constant pressure drop. 

For various reasons, laboratory permeability tests often yield results of limited value and in situ tests are generally thought to yield more reliable data The triaxial cell and the Rowe consolidation cell allow the direct measurement of permeability imder constant head with a back pressure and confining pressures more closely consistent with the field state. The Rowe cell allows either vertical or radial flow... 

The carrier gas method such as ASTM D 3985 is the commonly used for film oxygen permeability test. The test gas, oxygen flows on one side of the test piece and a second gas, nitrogen as carrier gas, flows on the other side and is quantitatively analysed to determine the quantity of test gas which has passed... 

The flow rates used in both injectivity and permeability testing with gelled polymer systems correspond to near wellbore shear rates. Typically, the rates have been between 0.5 and 2.0 feet/hour. Our testing has emphasized these conditions because of the economic and gel time delay limitations on the practical application of gelled polymer technology. 

For example, let us consider a sample with a perfectly water-wet surface (i.e., the contact angle measured through the water is equal to zero) which has been saturated with brine and, subsequently, driven down with oil to irreducible water saturation. It is usually assumed that at this stage there is still left a film of water covering the entire solid surface. Let us suppose that an imbibition-type relative permeability test is started at this point. The question may be asked whether in the vicinity of the irreducible water saturation all, or only a portion of the water contained in the sample will flow. 

The results of the relative permeability tests performed on the sample which had been treated with 2.5% Dri-Film solution are shown in Figures 6 and 7. In this case the first flow of the nonwetting phase (brine) in the drainage test was measured at a saturation of 11% pore volume, the wetting phase (oil) relative permeability was 0.004 at 54% pore volume wetting phase saturation, and the residual brine (connate water) saturation was 13.5% pore volume. The water curve extended to a value of 0.37 relative permeability units, compared with the highest point on the oil curve (in the imbibition test) of 0.185 relative permeability units. 

The results were compared with the oxygen diffusion, solubility, and permeability coefficients obtained for PET films under the same conditions. The water sorption isotherm for polylactide films was also determined. Diffusion coefficients were determined with the half-sorption time method. Also, a consistency test for continuous-flow permeability experimental data was run to obtain the diffusion coefficient with the lowest experimental error and to confirm that oxygen underwent Eickian diffusion in the polylactide films. The permeability coefficients were obtained from steady-state permeability experiments. The results indicated that the polylactide films absorbed very low amounts of water, and no significant variation of the absorbed water with the... 

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