Pleated filters

Particulate filtration removes suspended liquid or solid materials whose size, shape, and mass allow them to remain airborne at the air velocity conditions present. Filters are available in a range of efficiencies, with higher efficiency indicating removal of a greater proportion of particles and of smaller particles. Moving to medium efficiency pleated filters is advisable to improve lAQ and increase protection for equipment. However, the higher the efficiency of the filter, the more it will increase the pressure drop within the air distribution system and reduce total airflow (unless other adjustments are made to compensate). It is important to select an appropriate filter for the specific application and to make sure that the HVAC system will continue to perform as designed. Filters are rated by different standards which measure different aspects of performance. 

Cartridge filters Filters normally consisting of nonwoven V-pleated filter paper made into flat panels or cylindrical car-... 

The dry substance thus obtained is placed in a flask with 100 c c of chloroform, the spatula, pestle and dish being washed twice with 5 c c of hot water, which is added to the chloroform. v After addition of 0 25 c c. of concentrated ammonia, the liquid is boiled for 15 minutes under a reflux condenser. The boiling chloroform is filtered through a pleated filter, care being taken that the substance does not fall oij to the filter. The residue in the flask is similarly treated with four further quantities of 100 c c. of chloroform, the whole of the latter being then distilled to dryness from a flask on the water-bath and the last traces expelled in the oven. The residue is then washed with a little petroleum ether (10 c.c. in all, in two quantities), which is decanted on to a small filter. 

With almost all the determinations (naturally not that of the carbon dioxide), the beei should first be freed from the carbon dioxide present. This is done by pouring the beer repeatedly from one beaker to another or by shaking it vigorously in a large flask, the beer being afterwards filtered through a dry pleated filter. 

For precision applications where the work is especially sensitive to system contamination (e.g., disk drive, optical, or electronic components), point-of-use filtration is required. Currently absolute pleated filters of 0.1 micron rating are recommended. 

Filter the extract by gravity through fluted (pleated) filter paper (see Note 5). 

Figure 1.13 Schematic of cartridge membrane filters Top - deep-pleated filter with increased surface area (Pall Corp.) Bottom - traditional pleated filter with less surface area and non-uniform flow.

Pleated filter Platinum or glass dish Drying cabinet Analytical balance Desiccator Method... 

Add approximately 50 ml of hot ethanol to the evaporation residue of 1 or 2 litres water and use a glass rod to loosen and disperse any residues attached to the dish. After approximately 30 minutes on a boiling water bath, filter hot through a pleated filter into a glass dish. Then evaporate this first ethanol extract. Extract the residue once more with hot ethanol, and after filtration evaporate in a weighed dish (second extract). 

BHA, http ZAvww.baghonse.com/prodncts/dnst-collector-filters/pleated-filters BS 6524 (4) (1995), Method for determination of the surface resistivity of a textile fabric . British Standards Institnte, London Testrite Ltd, Halifax, UK. www.tes-trite.co.uk... 

Figure 1.41 Schematic of a pleated filter cartridge with spigot mount [left] and photograph, with permission from domnick hunter, showing cartridges mounted in a typical housing (righfi.

JP Patent 2003299924, Biodegradable pleated filter material and filter unit for air purification and liquid filtration , Omori, Taira, 2003. 

The mechanical and attritional properties of nanofibre nonwovens are inherently low. This can result in issues during conversion into product, eg, a pleated filter, as the integrity of the nonwoven can be disrupted during manufacture. The in-use mechanical stresses and abrasion conditions should be carefully considered when designing a product. The nanofibres are commonly laid upon a relatively inexpensive nonwoven support layer, eg, a spunbond fabric. 

US 6488731 Pleated filter made of a multi-layer filter medium. 2002. 

Figure 9.2 Diagram of a HEPA filter. An enlarged view of the pleated filter medium and the aluminum separators is shown on the right. (Courtesy of the Flanders Filter Co.)...

Membrane cartridge filters are extremely flexible and high in tensile strength. The cartridge construction is based on a multi-layer combination of filter media in pleated format. Those polymers that have been used extensively as filtration media in coarser grades are now widely used as membrane filters. A typical format has a cartridge fabricated from a pleated filter pack, which contains a very fine polyolefin fibre prefilter layer, two nylon membranes of the same pore (0.2 pm) size, and a downstream polypropylene support. The layers of nylon microporous membrane and polypropylene prefilter are pleated together and snpported by an inner snpport core. The end-caps and core are melt sealed in polypropylene. 

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