Filters particle

Granular Beds of Particulate Solids Beds of solids like sand or coal are used as filter media to clarify water or chemical solutions containing small quantities of suspended particles. Filter-grade grains of desired particTe size can be purchasea. Frequently beds will be constructed of layers of different materials and different particle sizes. 

Depending on the test method and test result, particle filters are classified as coarse, fine, HEPA, and ULPA filters (Table 9.2). Electrofilters are usually included in the fine filter group. Chemical filters are used for gases. 

Strainers are usually made from woven wire gauze, like a sieve, and though today the pre-size can be made very small indeed (BSI 300 mesh gauze separates particles of roughly 50 microns) they are mainly included for the exclusion of large particles. Filters deal with the removal of very much smaller particles. 

A portion of the rich amine flows through a particle filter and a carbon bed filter. The particle filters remove dirt, rust, and iron sulfide The carbon filter, located downstream of the particle filters, remo cs residual hydrocarbons from the amine solution. 

Oxidative catalytic converters are used to reduce CO and HCs originating from imperfect combustion in engines. At certain temperatures, these converters may also oxidize NO to NO2. Original equipment manufacturer (OEM) particle filters (PFs) employ NO2 to oxidize trapped soot at lower temperatures. However, the excess NO2 may escape from the system as tailpipe emissions. NO2 is very toxic to humans, and it also has impacts on atmospheric ozone-forming chemistry. Alvaraz et al. have stated that the primary NO2 emissions of modern diesel cars are increasing [76]. 

Studies on the particulate distributions from compressed natural gas (CNG) or diesel-fuelled engines with diesel oxidation catalyst (DOC) or partial diesel particle filter (pDPF) have also been performed. The results obtained are used as data for the model, to study the particle penetration into the human respiratory tracts. As a result, the number distribution of particles in different parts of lungs can be modeled [99-101]. Understanding the particle formation and their effects and finding the methods to ehminate the formed particulates from exhaust gas contribute to a cleaner urban environment and thus to a better quality of life. 

Under the EuroIV regulation (2005), the Diesel Particle Filter (DPF) emerged and is necessary for the heavily loaded applications. Renault plans to make a CSF offer for all the diesel product range. This system enables to treat nearly 100% of the particle matter (PM, soot). When loaded, the DPF requires a regeneration phase to bum the accumulated soot. This regeneration is mandatory to keep not only the engine performance and reliability, but also the DPF reliability itself. 

Overall, EGR and combustion/injection systems constitute the key factors to comply with the EuroIV standards (applied in January, 2005). The EuroIV step exhibits EuroIII NO and soot particles limits divided by 2. Besides, vehicle s weight is always increasing due to the introduction of new safety systems and equipment. Therefore, pollutants emissions increase and a supplementary effort to reach the normative threshold is to be made. To comply with this target, some evolutions have been introduced, as for example multi-injection or water-cooling of the EGR system. The NO,/particle compromise adjustment remains possible for most of the applications without any after-treatment system like the Diesel particle filter (DPF). 

DIESEL PARTICLE FILTER MANDATORY IN EUROV - ITS CONSTRAINTS... 

Because of the short liquid flow path of nano LC and the small orifice spray tip of the MS interface, column and flow path plugging is a common problem with nano LC-MS. Sample clean-up is critical for ensuring reliable daily operation and generation of quality data. Online desalting and particle filtering are particularly important steps. Four online sample clean-up factors should be considered with nano LC ... 

Herman, S. and Moulin, P.M. A particle filtering approach to passive radar tracking and automatic target recognition IEEE Aerospace Conference Proceedings, 2002. Vol.4, pp 1789-41808, 9-16 March 2002. 

Fig. 11 Extraction device consisting of A CO2 cylinder, B syringe pump, C oven, D extraction cell, E particle filter, F back-pressure regulator, G sampling tube...

Table 9-1 lists design features of the exposure chambers in the United States that have air-cleaning equipment. The facility at the University of Maryland Hospital, Baltimore, has a chamber with activated-charcoal and high-efficiency particle filters and controlled temperature and humidity. St. Vincent s Hospital and New York University, New York City, each have a clean-room facility. The University of Pennsylvania Hospital, Philadelphia, has a self-contained, reinforced-concrete... 

TABLE VI. Viability of Rabbit Alveolar Macrophages Exposed to Sub-Micron Particle Filters... 

St. Louis Sample Collection. Ambient aerosols were collected in St. Louis in 6-h Intervals with a TWOMASS automated sequential tape sampler. This sampler fractionated the aerosol into two size classes, fine particles having aerodynamic diameters less than 3pm, and coarse particles with diameters greater than 3pm. It was equipped with a beta-attenuation mass monitor to determine fine-particle mass (11). Only the fine particle filter was examined in this study. Pallflex E70 glass-fiber filter tape with a detachable cellulose backing (Pallflex Inc. Putnam, CT) was used with this sampler. An aerosol sampler operating from the same inlet manifold as the... 

Potential interferences in the measurement of nitric acid using this method include removal of gaseous HN03 on the Teflon particle filter and/or volatilization of particle nitrate collected on this Teflon filter. As discussed in Chapter 7, NH4N03 is a common particle component, but exists in equilibrium with gas-phase NH3 and HN03 ... 

In the alternative method (85), a second sampler, consisting of a Teflon particle filter followed by a quartz filter, is operated in parallel with a quartz-filter sampler. The carbon recovered from the quartz backup filter of this second sampler is subtracted from the organic C determination of the first sampler (Q - TQ strategy). The rationale for this alternative approach is to minimize the extent of sorption of vapor-phase carbon on the first (particle-collection) filter, which, otherwise, might significantly diminish the amount retained on the backup quartz filter. The need for an additional sampler and very accurate air volume measurements is a disadvantage. 

Diesel particle filters are a very efficient means of reducing PM mass emissions from diesel vehicles, but do not directly target NOx. However, most diesel particulate filter (DPF) systems contain catalytic materials which assist in the DPF regeneration (the combustion of PM accumulated on the filter to clean the DPF and prevent blockage). Such catalytic materials can have a similar impact to DOCs... 

Some reviews [5-7] have appeared on NCE-electrospray ionization-mass spectrometry (NCE-ESI-MS) discussing various factors responsible for detection. Recently, Zamfir [8] reviewed sheathless interfacing in NCE-ESI-MS in which the authors discussed several issues related to sheathless interfaces. Feustel et al. [9] attempted to couple mass spectrometry with microfluidic devices in 1994. Other developments in mass spectroscopy have been made by different workers. McGruer and Karger [10] successfully interfaced a microchip with an electrospray mass spectrometer and achieved detection limits lower than 6x 10-8 mole for myoglobin. Ramsey and Ramsey [11] developed electrospray from small channels etched on glass planar substrates and tested its successful application in an ion trap mass spectrometer for tetrabutylammonium iodide as model compound. Desai et al. [12] reported an electrospray microdevice with an integrated particle filter on silicon nitride. 

At times, failures in processing may introduce such materials as carbon adsorbent particles, filter aid, or inorganic compounds. In the last category, iron oxides and sulfides and sodium and ammonium salts have frequently been reported to be factors in the color problem,60 not only because of their own color but also because of their catalytic effect on the formation of coloring materials from sugars. Turbidity may also result from presence of traces of such salts as calcium phosphate, silicate, or sulfate. 

The filtered sample is neutralized with ammonia, and then buffered sodium diethyldithiocarbamate (SDDC) is added. The pH is adjusted to approximately 6, and the sample, in a separatory funnel, is shaken thoroughly. The analyte is then extracted twice with organic solvent. Nitric acid is added to the solvent, and it is evaporated to dryness on a hotplate. The residue is taken up in nitric and hydrochloric acids, and the dissolved residue is analyzed by AAS. It should be noted that the soluble metals are those that pass through the 0.45-pm filter, while total metals do not include those that are so tightly bound into the particles filtered out that they were not solubilized in the slow, mild acid leaching process to which the sample was exposed. For a true total metal analysis, an acid digestion would be required. 

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