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Valve permeation

Permeate Divert Valves Permeate divert valves (or any other valve on the permeate line) should be set to close only after the other valve has opened completely or the RO system has shut down. If all permeate valves were to be closed while the RO was operating, permeate would have nowhere to go and pressure would build up quickly on the permeate side of the membrane. [Pg.298]

The vapor vent valves are connected to the tank vapor control valve, and ultimately to the carbon canister by tubing that is resistant to swelling in the presence of fuel vapors. The tubing material must also have a low HC permeation rate, so that the evaporative emissions are not increased due to release of HC molecules. The tank vapor control valve connects the carbon canister to two fuel tank vapor sources the vapor vent valve lines and a refueling vent tube. [Pg.245]

Although relatively unknown, the instrumentation for 2DLC was conceived and implemented by Emi and Frei (1978). They reported the valve configuration presently used in most comprehensive 2DLC systems. However, they automated neither the valve nor the data conversion process to obtain a contour map or 2D peak display. They used a gel permeation chromatography (GPC) column in the first dimension and a reversed-phase liquid chromatography (RPLC) column in the second dimension and studied complex plant extracts. [Pg.13]

When the oxide is formed by anodizing in acid solutions and the sample is then left to rest at the OCP, some dissolution can occur. This process has been studied by a numbers of authors,70-75 especially in relation to porous oxides [cf. Section 111(4)]. It was found that pore walls are attacked, so that they are widened and tapered to a trumpet-like shape.70 71 Finally, the pore skeleton collapses and dissolves, at the outer oxide region. The outer regions of the oxide body dissolve at higher rates than the inner ones.9,19 The same is true for dissolution of other anodic oxides of valve metals.76 This thickness dependence is interpreted in terms of a depth-dependent vacancy concentration in the oxide75 or by acid permeation through cell walls by intercrystalline diffusion, disaggregating the microcrystallites of y-alumina.4... [Pg.423]

After preformation, the substrates and carbon dioxide were supplied continuously. The membrane reactor was pressurized at the feed side up to 20 MPa with the reaction mixture. A trans-membrane pressure was created by opening a needle valve on the permeate side after which the continuous process started. [Pg.96]

After an activation period of 4 h, the conversion showed a maximum of 40% followed by a steady decrease in conversion (Figure 4.38). Overnight, the pressure was decreased to 6 MPa and the needle valve on the permeate side was closed. This shutdown procedure caused the catalyst to precipitate and no reaction occurred anymore. The precipitated catalyst can be used for a new cycle by pressurization of the membrane reactor, redissolving the catalyst. At the end of the third run the conversion had dropped to 33%. A TON of 1.2xl05 in 32 h (t 62 min) was obtained. ICP-AAS analysis of the permeate stream indicated complete retention of the catalyst. The authors propose possible traces of oxygen as the cause of the decrease in activity of the catalyst. [Pg.97]

Ideally, the axial velocity through the cross-flow unit should be greater than about 4-6 m/s to minimize the boundary layer of particles near the membrane surface. The wax permeate flow from the filter is limited by a control valve actuated by a reactor-level controller. Hence, a constant inventory of slurry is maintained within the SBCR system as long as the superficial gas velocity remains constant. Changes in the gas holdup due to a variable gas velocity are calculated... [Pg.279]

As presented in Figure 15.10, after 100 h TOS the permeate valve was closed, and thus the transmembrane pressure fell to zero. The pilot plant remained in a standby mode and unmanned for approximately 75 h. During this period, the catalyst slurry was circulated through the cross-flow filter, without permeate flow radially through the filter membrane (i.e., test conditions were constant with the... [Pg.286]

Insulin permeation rate, 9 69 Intake valve deposits (IVD), 12 409—410 Intake valve detergents, 12 409 Intalox saddles, 1 28 8 770... [Pg.480]

Blood is pumped away from the heart through arteries it permeates the tissues through networks of very small capillaries where nutrient delivery, gas exchange and waste removal occur and is finally returned to the heart via the veins. The structures of the arteries and veins differ in important ways. First, the veins have one-way valves which prevent the back-flow of blood and second, the walls of the arteries are much thicker, due largely to the layer of smooth muscle cells. Both types of vessel are lined on their inner surface with endothelial cells. Refer to Figure 5.2. [Pg.130]

A typical test loop includes a pump capable of pressure development to 1000 psig and sufficient valving and piping to permit multistation installation of fiber samples. Feed solutions are delivered from reservoirs which are thermostated and isolated in order to maintain constancy of temperature and composition. The facility is so established that both permeate and concentrate are returned continuously to the reservoir. [Pg.370]

Test leaks (also known as standard leaks or reference teaks) normally comprise a gas supply, a choke with a defined conductance value, and a valve. The configuration will be in accordance with the test teak rate required. Figure 5.9 shows various test leaks. Permeation teaks are usually used for leak rates of 10 ° < < 10, capillaries, between 10 and 10 ... [Pg.118]

Osada et al. [52] have also grafted PMAA to a porous substrate in order to achieve an environmentally sensitive membrane. This sensitivity was termed a chemical valve function because mechanochemical forces caused the pores to enlarge and contract. PMAA was grafted onto poly(vinyl alcohol) (PVA) films which had a mean pore radius of 4 pm. The water permeation of the membrane was strongly affected by the conformational state of the PMAA grafts. At low pH the chains were contracted and the water permeability was... [Pg.146]

Figure 2. Schematic representation of RO system. Feed solution travels from reservoir (F) via pump (A) through cells (C) where a portion of the water permeates the cells. Pressure in the system is adjusted by the regulator (E) and monitored by gauge and valve system (D). Damping of pressure fluctuations is achieved by nitrogen pressure and the system (B). Figure 2. Schematic representation of RO system. Feed solution travels from reservoir (F) via pump (A) through cells (C) where a portion of the water permeates the cells. Pressure in the system is adjusted by the regulator (E) and monitored by gauge and valve system (D). Damping of pressure fluctuations is achieved by nitrogen pressure and the system (B).
Figure 9. Configuration of the DS-IC system A, clean air input B, mass-flow controller C, permeation device chamber D and H, vents E, needle valve-rotameter F, needle valve G, mass-flow meter I, diffusion scrubber Jy scrubber liquid reservoir K, needle valve-rotameter L, suction pump M, injection valve Ny peristaltic pump O, eluent flow F, downstream chromatographic components and Q, sample loop. (Reproduced from reference 96. Figure 9. Configuration of the DS-IC system A, clean air input B, mass-flow controller C, permeation device chamber D and H, vents E, needle valve-rotameter F, needle valve G, mass-flow meter I, diffusion scrubber Jy scrubber liquid reservoir K, needle valve-rotameter L, suction pump M, injection valve Ny peristaltic pump O, eluent flow F, downstream chromatographic components and Q, sample loop. (Reproduced from reference 96.
In the case of the counter-flow/sweep membrane module illustrated in Figure 4.18(c) a portion of the dried residue gas stream is expanded across a valve and used as the permeate-side sweep gas. The separation obtained depends on how much gas is used as a sweep. In the calculation illustrated, 5 % of the residue gas is used as a sweep even so the result is dramatic. The concentration of water vapor in the permeate gas is 13 000 ppm, almost the same as the perfect counter-flow module shown in Figure 4.18(b), but the membrane area required to perform the separation is one-third of the counter-flow case. Mixing separated residue gas with the permeate gas improves the separation The cause of this paradoxical result is illustrated in Figure 4.19 and discussed in a number of papers by Cussler et al. [16]. [Pg.187]

In the case of the counterflow/sweep membrane module illustrated in Figure 8.5 (c), a portion of the dried residue gas stream is expanded across a valve and used as the permeate-side sweep gas. The separation obtained depends on how much gas is used... [Pg.174]


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See also in sourсe #XX -- [ Pg.22 ]




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