Plastic filters

The simplest sand filter is merely a bed of sand through which the water moves at very slow rates. A high-speed version has been developed that uses layers of sand of different sizes (Fig. 16-4). The water passes through the coarsest layers first.50 Sometimes the layers may contain compounds other than sand, such as coal or garnet. When space is a problem a combination unit involving a plastic filter cloth and sand can be used.51... 

Dust samples were collected by the probe/filter configuration shown in Figure 2. The filter used to trap the explosive dust was a 37mm plastic filter cassette. To monitor the actual flow rate, a rotometer was used. The calculation for each traverse point dust concentration was obtained from... 

Spent filter materials Plating and chemical conversion Cotton, activated carbon, paper, ceramic, diatomaceous earth, polypropylene and other plastic filter materials, and the same contaminants listed above under "filter sludges."... 

The result of our effort to develop the best possible detector for MES is as follows. Our detector has a resolution of approximately 2 KeV (fwhm) at 15 KeV as shown in Figure 6. There is virtually no deterioration in performance over a period of several months. The overall efficiency of the detector when used for MES with 14-KeV y-radiation is such that a 0.001-inch thick sample of stainless steel type 302 (natural isotopic abundance) gives a spectrum with the peak height some 400% of the base line, Figure 7. (For comparison, when we started we were quite content with 50%.) With our 10-mc Co-57 source, the data acquisition rate in the peak is approximately 500 counts/min. This means that in a matter of a minute or less one obtains a recognizable spectrum. As a bonus, the observance of 6-KeV x-rays yields an effect of approximately 50% of the baseline. To accomplish this, we interpose a plastic filter between the source and the sample to absorb most of the 6-KeV radiation from the source (which does not contribute to the effect but is elastically... 

R0)2P02 with R groups in the C8-C16 range], that possesses high affinity for calcium ions. The ion exchanger is held in a porous, plastic filter membrane that separates the test solution from the inner compartment, containing a standard calcium chloride solution (Fig. 5.10). The preferential uptake of calcium ions into the membrane can thus be represented as... 

SHEET FILTRATION. Sheet filters consist of a tubular steel chassis or a freestanding filter chassis in which square metal or plastic filter plates are vertically arranged. The filter plates are fluted plates made of ribbed material or tubular frames with perforated plates. 

Column (glass or plastic, containing sintered glass or plastic filter to retain the affinity resin). The size of the column should be sufficient to facilitate applicadon and allow for a small reservoir for effluent, wash, and eluant liquids. 

Sterile 50 mL measuring cylinder, sterile plastic filter funnel. 

Plastic test tubes Plastic microtiter plates Plastic disks or beads Plastic filters or disks Glass fiber filters... 

Optimizing the permeability measurements to avoid adsorption to plastic, filters, or accumulation within the cell monolayer seems highly relevant for increasing the... 

Company DD Large chemical company/plastics, filters... 

Figure 2.5 UV transmission curves of Corning 0-53 Pyrex glass filter and a plastic filter made from overhead transparency film.

For consistency one needs to use an artificial photon source that has an output with a spectral power distribution as near as possible to that of sunlight. The output from the source may then be filtered, for example, with the glass or plastic required to simulate that type of packaging. Chapter 2 gave the spectral power distribution of sunlight and transmission characteristics of certain glass and plastic filters. 

From these studies, it was also reported by Laurene et al. (2311, 2312) that the effectiveness of the selective filtration of plasticized filter-tip cigarettes decreased during the shelf life... 

For excitation at 254 nm, a combination of filters is used that transmits only below 300 nm, namely a 7-54 filter plus a special plastic filter, as shown in Figure 9.5A. Alternatively, because the plastic filter gradually decomposes and must be replaced, a mercury-line interference filter may be used. This is a single, permanent filter for isolating the 254-nm line without transmitting the 313-nm, etc., lines emitted by the low-pressure mercury arc. 

Figure 9.5. A plot ofpercent transmittance versus wavelength for several types of filters used in fluorescence. A The 7-54 filter solid line) a plastic filter that absorbs radiation above 300 nm dotted line) is used in combination with the 7-54 filter to isolate the 254-nm mercury line. B The...

Another problem was to choose the most efficient method of exciting salicylic acid, which has only one useful excitation band (at 308 nm). One approach was to use a special phosphor-lamp source emitting between 270 and 340 nm with a peak at 306 nm this gave good sensitivity for salicylic acid. Another approach was to use the somewhat weak 313 nm line emitted by a low-pressure mercury-arc lamp, selected with a combination primary filter consisting of the 7-54 filter along with a plastic filter used to cut out the 254-nm mercury line. This procedure essentially excited only the salicylic acid, not ASA. In both cases, a sharp-cut filter with 37% T at 465 nm was used to exclude any possible emission by ASA. 

F, porous plastic filters E. PTFE tubings with flanged ends and R. sorbent packing... 

The suitability of a filtration process can be assessed in a small laboratory pressure filter with a filter area of about 20-50 cm and a capacity of 0.3-1 L, in which various metal and plastic filter materials can be tested (Figure 2.3.10-1). The pore width is about 10-100 jum. The filter should be heatable and coolable.The experiment is evaluated in terms of the applied gas differential pressure AP, the filter area A, the filtrate volume V, the final filter cake height H, and the filtration time t until gas breakthrough according to Equation (2.3.10-1). 

All three have their importance in the field of plastic materials, whereas CA is by far the most widely produced derivative (expected to reach 980 000 metric tons by 2015 - see http //www. prweb.eom/releases/cellulose acetate/flake plastics filter tow/prweb8067438.htm, accessed 21 June 2013) mainly used for cigarette filter tow, which is, however, not melt spun but produced by dry spinning in acetone. Since synthesis methods for CA and the mixed esters mentioned basically differ only in the starting materials (acid and acid anhydrides), only the CA process is described briefly in the following section. 

The analysis of plasticizers in indoor air is most fiequently done using either adsorbent tubes (without a front filter) or sample trains. Sample trains corrsist of a filter followed by an adsorbent. They are interrded to separate particles botmd fiom gaseotrs plasticizers. Filters are made either of qirartz or glass fiber. Adsorberrts to trap the vapor phase plasticizers may be XAD CIS extraction disks, polyrrrethane foarrr, - or charcoal." " ... 

New prototype materials with controlled molecular transfer properties have to be engineered into fabrics, plastics, filters and other robust materials that can be used to develop and test better protective gear. Properly engineered new materials with tailored mass and heat transport... 

For direct measurement, the sample is prepared by drawing a certain amount of air through a filter. To measure a- and jS-activities, the aerosols must be retained on the filter surface. Membrane filters, plastic filters, and glass fiber filters are used. For y-activity measurement, the filters need not retain the sample at the surface. 

Recently Prokic (1996) developed a system of detection for environmental monitoring. The system consists of three sintered CaS04 Dy pellets and one MgB4(>7 Dy,Na detector. Two Ca sulfate detectors are filtered by 2 and 1.5 mm Cu respectively and the third is only covered by plastic. The low-Z (Z = 8.55) Mg borate detector is covered by only a plastic filter. The Mg borate detector showed one TL peak near 190 C. It was prepared from very pure materials and a special preparation method. Its TL sensitivity exceeded that of TLD-100 by a factor of 6-15. The low-dose limits were 2 and 3 pGy for the Ca sulfate and Mg borate detectors respectively. The detector with the 2 mm Cu filter was used for the determination of the ambient dose equivalent H (10) and that with the 1.5 mm Cu served for the determination of H (0.07) for photons. The ratio of the readings of the unfiltered and the 2 mm Cu filtered detectors provided information of the spectral distribution of the radiation. Wemli (1990) developed a TLD system very similar to the above, to measure the ICRU dose quantities H(10) and H(0.07) in evironmental dosimetry. 

Calhoun, C. C. (1972), Development of Design Criteria and Acceptance of Specifications for Plastic Filter Cloth, US Army Corps of Engineers W.E.S, Vicksburg, MS Technical Report S-72-7, p. 83. 

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