Filter efficiency

Chen R Q and Guo H 1996 A general and efficient filter diagonalization method without time propagation J. Chem. Phys. 105 1311... 

The high-pressure water supply service is employed for the operation of the ordinary filter pump, which finds so many applications in the laboratory. A typical all metal filter pump is illustrated in Fig. 11, 21, 1. It is an advantage to have a non-return valve fitted in the side arm to prevent sucking back if the water is turned off or if the water pressure is suddenly reduced. Theoretically, an efficient filter pump should reduce the pressure in a system to a value equal to the vapour pressure of the water at the temperature of the water of the supply mains. In practice this pressure is rarely attained (it is usually 4 10 mm. higher) because of the leakage of air into the apparatus and the higher temperature of the laboratory. The vapour pressures of water at 5°, 10°, 15°, 20° and 25° are respectively 6-5, 9-2,12-8, 17 5 and 23 8 mm. respectively. It is evident that the vacuum obtained with a water pump will vary considerably with the temperature of the water and therefore with the season of the year in any case a really good vacuum cannot be produced by a filter pump. 

Group Efficiency Filter type Stain test efficiency, % Arrestance, %... 

Cold-generated DOP A cold-generated aerosol dioctylphthalate (DOP) test, used to measure the efficiencies of high-efficiency filters. A hot DOP test may also be used. 

Efficiency, filter The ratio of the number of particles retained by a filter or other air cleaning device to the number of particles entering, expressed as a percentage. 

For illite (Figure 3B) the total amount of Cs adsorbed is two orders of magnitude larger (ca. 0.26 atoms/A2) due primarily to the permanent charge developed by substitution of Al for Si in the tetrahedral sites and to less efficient filtering of the solution caused by lower sample permeability. The maximum amount of hydrated Cs that can be accommodated on the illite surface is ca. 0.023 atoms/A, close to the amount... 

A microparticulate hplc column is a very efficient filter, and if the mobile phase contains any particulate matter, or acquires it from the pump and/or the injection valve due to wear, it will collect at the top of the column. If this happens, the pressure drop across the column for a given flow will gradually increase, and the column may eventually become completely blocked. To prevent this happening, the mobile phase should always be filtered before use, preferably through a 0.5 p,m porosity filter, and guard and scavenger columns should be used as a matter of routine (see Section 5.3.2). 

Filtration is an efficient and inexpensive method for removing dust, particulates and bioaerosols from indoor air. High efficiency filters can remove up to 95 % of airborne particles as small as 0.3 microns. However, odor associated with gaseous VOCs cannot be removed by simple filtration and must be captured using adsorbents such as activated carbon and charcoal. Frequent replacement is needed since these adsorbents have finite capacity and cannot be regenerated. The aim of this project is to develop an effective remediation technology for common airborne VOCs found indoor. 

Airborne particles, bacteria, fungi spores and allergens will be removed by air filtration, which is often cheaper and more effective than electrostatic precipitators and ionizers. A disposable, high-efficiency filter capable of removing at least 95 percent of particles with size down to 0.3 micron will be installed. A washable coarse filter that removes fifty percent of particles larger than 10 microns will be used as a pre-filter to extend the life of the high efficiency filter by at least a third. An inexpensive sensor will be included to indicate when filter replacement is necessary. 

Zeolites have recently found application in the field of sunscreens, which are organic compounds acting as efficient filters of UV-A and UV-B (Table 12.1). 

The insertion of an RC circuit in the feedback electronics right before the high-voltage amplifier for the z piezo has some other advantages. First, much of the high-frequency noise is efficiently filtered out. Second, it facilitates the realization of the electronics for spectroscopic study, which we will discuss in the following section. 

Removal of the fine sand has reduced the stopping power or breakthrough efficiency. Filter efficiency is also reduced. Filter efficiency has been directly related to the media particle surface area. The number of particles in a given volume of a dual-media filter has been reduced. The average size of the particles has also increased. As the filtered material is relatively loosely held in the coal layer, the materials are dislodged and will likely penetrate the sand layer and appear in the filter effluent if a flow change or applied solids surge occurs. 

High efficiency filter Particulate Cadmium iodide on Chromosorb B Elemental... 

One final comment regarding the time constant in chromatographic detection limits concerns the noise level observed on the baseline. Large time constants serve as efficient filters for (high frequency) noise. Therefore, if a great reduction of the time constant is not... 

Figure 2. Chemical noise in MS Heft-hand side,) obscures signal (128 ) due to analyte, while in MS/MS fright-hand side,) chemical noise is more efficiently filtered out by the extra stage of mass separation.

High-efficiency filters (HEF) are pressure filters designed to remove turbidity and SDI in water. They were originally applied to cooling towers, to reduce the concentration of suspended solids in those systems. 

Figure 8.10 Top-over-bottom high efficiency filter.

Figure 8.11 Vortex high efficiency filter. Courtesy ofSonitec, Inc.

Table 8.3 Performance comparison of multimedia and high-efficiency filters.

High-efficiency filters are gaining in acceptance for RO pretreatment.3 These filters offer some advantages over conventional multimedia filters, the most important of which may be the ability to remove particles down to 0.25 microns in size for the top-over-bottom filters, and 0.45 microns for the vortex filters. 

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