Filtering gases

Phthalocyanines are excellent lubricants at temperatures of 149—343°C (191). Combinations with other lubricants, like grease, molybdenum, or tungsten sulfides, have found appHcations in the automotive industry or professional drilling equipment (192—195). Further uses include indicators for iron(Il), molybdenum(V), and uranium(IV) (196) or redox reactions (197), medical appHcations like hemoglobin replacements (198) or sterilisation indicators (199), or uses like in gas filters for the removal of nitrogen oxides from cigarette smoke (200). 

Process Description Gas-separation membranes separate gases from other gases. Some gas filters, which remove hquids or sohds from gases, are microfiltration membranes. Gas membranes generally work because individual gases differ in their solubility and diffusivity through nonporous polymers. A few membranes operate by sieving, Knudsen flow, or chemical complexation. 

SX gas filters and combined filters against specific named compounds used m respiratory... 

At the downstream end of the pipeline it is necessary to disengage the solids front the gas and this is most usually carried out in cyclone separators (See Volume 2, Chapter 8). However, there may be a carry-over of tine particles which must be eliminated before the gas is vented, and gas filters or electrostatic precipitators may be used for this purpose (See again Volume 2, Chapter 8). At the upstream end, the particles must be introduced using some form of positive feeder, such as a rotary valve or a blow tank. 

The SU5 beamline [89] at the Super-ACO synchrotron (LURE, Paris ) employed an electromagnetic undulator to produce fully variable polarization in the VUV region [83, 90, 91]. This beamline was equipped with a gas filter for the suppression of unwanted higher order radiation [92] and had a VUV polarimeter [93] permanently installed just before the experimental chamber that could be rapidly lowered into the beam for polarization determinations. Full polarization analyses had been performed in commissioning, with 53 values ranging from 0.9 to 0.96 for rep and from 0.9 to 0.99 for Icp [93]. The remainder was determined... 

In addition to inlet gas filtering, it is usually necessary to use some form of filter downstream of the fluidized bed to avoid solid carryover. For fairly large particles, this is usually achieved by bag filters or screens for very fine powders, abaghouse and cyclones may be necessary. 

Open die drying gas (filtered pressurized air, or any inert gas) to the waveguide just above die resonator. 

Herget W.F., Jahnke J.A., Burch D.E., Gryvnak D.A., Infrared gas-filter correlation instrument for in situ measurement of gaseous pollutant concentrations, Appl. Opt. 1976 15 1222-1228. 

Detection techniques. Detection techniques commonly used for CO include two infrared techniques, TDLS and NDIR (also known as gas filter correlation, GFC), and gas chromatography with various detectors. The principles behind TDLS and NDIR have been... 

G = Gas Filters MFC = Mass Flow Controllers R = Reactor Setup CG = Carrier Gas FID = Flame Ionization Detector... 

Earths and Alkalies. — Dissolve 5 gm. of lead acetate in about 100 cc. of water, and precipitate the lead h-oin the solution with hydrogen sulphide gas filter, evaporate the filtrate, and ignite the residue. The weight of the latter should then not exceed 0.001 gm. 

Calcium and Alkalies. — Dissolve 2 gm. of lead peroxide in 25 cc. of hydrochloric acid. Dilute the liquid with 200 cc. of water, boil ten minutes to expel the chlorine, and supersaturate with hydrogen sulphide gas. Filter off the precipitate, evaporate the filtrate, ignite and weigh the residue. The weight should not exceed 0.002 gm. 

Figure 21. Emission in the 1800-2800 cm-1 region following the IRMPD of CH2F2 (25 mTorr) in the presence of NO (lOOmTorr) and Ar (lOTorr). Emission from N20 (001) and C02 (001) are seen at long times following the vibrational cascade of highly excited species their presence at early times [together with CO(v = 1)] was established by cold gas filter experiments. N20 is the dominant emitter, and is believed to originate from the reaction sequence (20), (17).

Carbon Monoxide. Methods for determining carbon monoxide include detection by conversion to mercury vapor, gas filter correlation spectrometry, TDLAS, and grab sampling followed by gas chromatograph (GC) analysis. The quantitative liberation of mercury vapor from mercury oxide by CO has been used to measure CO (73). The mercury vapor concentration is then measured by flameless atomic absorption spectrometry. A detection limit of 0.1 ppbv was reported for a 30-s response time. Accuracy was reported to be 3% at tropospheric mixing ratios. A commercial instrument providing similar performance is available. 

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