Filter media damage

The leak test ( DOP test situ test to verify that filters do not leak on inatidlation. The leak test is not a second efficiency test. It is intended to dis> close leaks around the frames and damage to the filter medium. An aerosol of oil particles with mass median diameter of 0.3 pm is used to challenge the filter deteaion Is by aerosol photometry on the downstream side. Standards of integrity are specified as maximum permissable percentages of the upstream concentration of particles that can be recovered downstream of the filler. 

Vertical vessds can accommodate up to 80 m of vertical plate larger areas, up to 300 m, are attainable with vertical leaves in horizontal vessels. Plate spacing must be considered, in relation to the volume of cake filtered per batch. Adequate space must be allowed between the leaves for cake deposition and subsequent discharge. Bridging of solids between plates can lead to les thy discharge times and, in some circumstances, damage to the filter medium... 

To avoid chemical or thermal damage to the yams, the choice of material for construction of the filter medium for any particular filtration application is important. Historically, filter fabrics were produced by weaving yarns spun... 

After specifying the filter type and the optimum operating conditions, the remaining issue for a filter design is the selection of the most suitable filter medium. In a filtration proeess, the fundamental role of a filter medium is to separate efleetively the particulates from a flowing fluid to provide a sufficiently clean filtrate without clogging and damaging the medium (i.e., low... 

Abrasive particles contained in a hydraulic oil system, if unfiltered, enter the system, they would damage sensitive components like pumps, valves, and motors. The nonwoven hydraulic filter is designed to remove these parficles from the oU flow to prevent hydraulic system failure from any premature component wear. Nonwoven filters either contain novel materials, such as magnetic polymer fibres, or have special designed structures (eg, multilayer composite filter medium for serial filtration ) that are employed to filter the solid abrasive particulates, soft particles, corrosive chemical particles, and some microorganisms. 

Synthetic monofilament fabrics, because of their ductility and manory, may be flexed repeatedly without work hardening and fatigue. They may be folded or dented with less chance of damage compared with a metal cloth, and they are lighter in weight. Some appfications require the filter medium to have the physical properties of the synthetic monofilament, but with a metallized surface for static electricity dissipation. Accordingly, a metallized polyester monofilament fabric is produced coated with a 2 pm thickness of luckel. 

Transfer the solution to a centrifuge tube and centrifuge down to a loose 5 mL pellet. We recommend a medium speed for 10 min. Decant off excess liquid. (Note Miller and Scholin [6] developed a system using a filter tube and filtration manifold that reduces sample processing time and causes less cell damage than centrifuging.)... 

Containers, media and seeds. Glass Petri dishes, 100 x 15 cm, were used with two sheets of 75-mm Whatman 41 filter paper as the absorptive medium. Ten seeds of TAM105 wheat were placed in a radial pattern with the micropyle end toward the center between the two sheets of filter paper. Seeds were hand-selected for normal size and absence of damage. TAM105 was selected because it is the variety used in the ongoing field research on conservation tillage practices. The bottom section of each Petri dish cover was covered with a square of kitchen-type plastic wrap to retard moisture loss before the lid was pressed on. 

Cell monolayers grown on Transwell filters have to be washed twice with freshly prepared and prewarmed HBSS. To avoid damage of the monolayer by hydrostatic pressure, first the medium from the basolateral compartment and then from the apical compartment has to be removed. The apical compartment is filled with 500 iL of fresh buffer and then the basolateral compartment with a volume of 1500 pL. 

Sintered-glass (also called fritted-glass) crucibles are manufactured in fine, medium, and coarse porosities (marked/ m, and c). The upper temperature limit for a sintered-glass crucible is ordinarily about 200°C. Filtering crucibles made entirely of quartz can tolerate substantially higher temperatures without damage. The same is true for crucibles with unglazed porcelain or aluminum oxide frits. The latter are not as costly as quartz. 

In some cases of pilot scale filtration, entire units have been enclosed as a secondary containment precaution (see Chapter 8). A recent commercial development is the MBR-Sultzer dynamic filter which is available in three sizes. Dynamic filtration is the same as cross flow filtration with little or no recirculation. The cross flow effect is derived from the spinning of the inner surface filter. This type of filter is more efficient, has a lower pump rate and a much higher linear velocity across the filter surface, than conventional cross flow filtration units. There is also little or no damaging effect on sensitive cells. The medium size has the same capacity as the Westfalia SA-7 separator. Van Hemert and Tiesjema concluded that the dynamic filter is suitable for work requiring strict aseptic and primary containment conditions. The use of a double mechanical seal on the rotating shaft could offer a higher degree of containment if required. 

Membrane Filtration Method The water sample (generally 100 mL) is filtered through a 0.45 xm (sometimes 0.22 xm) sterile filter thereby retaining the organisms on the filter surface. With face upward, the filter is then simply placed on the surface of a culture medium and incubated. Alternatively, before incubation, the filter may be placed on an absorbent pad that is sterile and saturated with broth. This method is suitable for examining relatively large volume of water with low turbidity [77]. The bacteria are also not heat-shocked in the process. However, the bacterial cells may be damaged due to excessive filtration pressure. 

Because of their construction, HEPA filters are very sensitive to rough handling and can be damaged very easily. The filter media can separate from the frame, and careless use of the cabinet can result in punctures of the medium from tubing or damage from Bunsen... 

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