Dioxide Systems

The acceptance test of a carbon dioxide total flooding or local application consists of  

NFPA 12 should be followed for the acceptance testing of carbon dioxide systems. 

WARNING Personnel should not enter the test area due to the possibility of asphyxiation. The test area should be treated as an IDLH atmosphere until testing proves otherwise. 

For fire extinguishment or inerting purposes CO2 is stored in liquid form that provides for its own pressurized discharge. 

Carbon dioxide may be applied for fire extinguishment through three different mechanisms  

Fixed systems are classified in the manner they are stored. Low pressure 2,068 kPa (300 psi) or high pressure 5,860 kPa (850 psi) systems can be specified. Low pressure systems are normally provided when the quantity of agent required exceeds 907 kgs (2,000 lbs ). Protection of electronic or electrical hazards usually requires a design concentration of 50% by volume. NFPA 12 provides a table specifying the exact concentration requirements for specific hazards. As a guide, 0.45 kgs (1 lb.) of CO2 liquid may be considered to produce 0.23 cubic meters (8 cu. ft. ) of free gas at atmospheric pressure. 

Fixed CO2 systems are almost used extensively for protecting highly valuable or critical where an electrically non-conductive, non-residue forming agent is desired and where the location is unmanned. In the hydrocarbon industries CO2 systems are usually provided to protect 

COz is a nonflammable gas, therefore it does not present a tire or explosion hazard. The gas is generally considered toxic but will displace oxygen in the air, since it is 1.5 times heavier that air it wall settle and air supplies will be pushed out of the area. The CO2 gas is considered an asphyxiation hazard to personnel for this reason. Since the gas is odorless and colorless it cannot be easily detected by human observation in normal environments. Fire protection CO2 gas is normally stored under high pressure as a liquid and expands 350 times its liquid volume upon release. 

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The fugacity coefficient of thesolid solute dissolved in the fluid phase (0 ) has been obtained using cubic equations of state (52) and statistical mechanical perturbation theory (53). The enhancement factor, E, shown as the quantity ia brackets ia equation 2, is defined as the real solubiUty divided by the solubihty ia an ideal gas. The solubiUty ia an ideal gas is simply the vapor pressure of the sohd over the pressure. Enhancement factors of 10 are common for supercritical systems. Notable exceptions such as the squalane—carbon dioxide system may have enhancement factors greater than 10. Solubihty data can be reduced to a simple form by plotting the logarithm of the enhancement factor vs density, resulting ia a fairly linear relationship (52). 

Various lithium salts and butyrolactone or PC—DME mixtures are usually used as electrolytes. The close competitive performance of CF and MnO cathodes is evidenced in Table 3. The constmction of cells is also similar for the two systems. In addition to uses mentioned for the lithium manganese dioxide system, some unique apphcations such as lighted fishing bobbers have been developed for the Japanese market. 

Carbon dioxide systems-Tliis system can be used where there is a handling and storage of gaseous and flammable materials, electrical equipment, and hazardous solids by introducing an inert gas (such as carbon dioxide) into the area in order to reduce the concentration of oxygen to the point where the fire will be extinguished. 

Carbon dioxide systems often used on Class B fires. 

Papers dealing with this topic are exhaustively reviewed in Comprehensive Heterocyclic Chemistry I (84CHEC-I(6)235) and II (96CHEC-II(3)373). Nevertheless, little information is available on the 5-oxides. Recently, the heteroaromaticity of thiazole compared with isothiazole and thiadiazole 5,5-dioxide systems was studied (97MI1). Quantum-chemical calculations and X-ray studies were performed on 3,3 -di[l,3-thiazolidin-4-one] derivatives (95JCC(25)589) studied for their potential biological activity (97FA(52)43). 

Pressure-induced phase transitions in the titanium dioxide system provide an understanding of crystal structure and mineral stability in planets interior and thus are of major geophysical interest. Moderate pressures transform either of the three stable polymorphs into the a-Pb02 (columbite)-type structure, while further pressure increase creates the monoclinic baddeleyite-type structure. Recent high-pressure studies indicate that columbite can be formed only within a limited range of pressures/temperatures, although it is a metastable phase that can be preserved unchanged for years after pressure release Combined Raman spectroscopy and X-ray diffraction studies 6-8,10 ave established that rutile transforms to columbite structure at 10 GPa, while anatase and brookite transform to columbite at approximately 4-5 GPa. 

Hindered rotation, 33, 34 internal, 367 Homopolymer, 168, 183 Hot bands, 374 Hot lattice, 4, 11, 21 Hydrates, 7, 9, 21, 31, 41 crystallization, 44 Hydrochloric acid clathrates, 2 in hydroquinone, 7 Hydrogen, bound, 4, 175 bromine hydrate, 35 4- carbon dioxide system, 110 4 carbon monoxide system, 96, 108 chloride hydrate, 35 clathrates, 2 chloride, 30... 

Metallic solutions, 120 Methacrylonitrile, 155 Methane, -f carbon dioxide system, 97 in clathrates, 30, 41 hydrate, 33, 34, 47... 

K. Kordesch, L. Binder, W. Taucher, C. Faistauer, J. Daniel-lvad, The rechargeable alkaline-zinc manganese dioxide system, Power Source 14, (Eds. Attewell, T. Keily), Internatl Power Sources Committee, 1993. 

To illustrate this thermodynamic consistency test, Figs. 15, 16, and 17 show plots of the appropriate functions needed to calculate Areas I, II, and III, respectively, for the nitrogen-carbon dioxide system at 0°C the data are taken from Muirbrook (M5). Fugacity coffiecients were calculated with the modified Redlich-Kwong equation (R4). 

A highly selective and rapid oxidation of sulphides to sulphoxides occurs when hydrogen peroxide/selenium dioxide system is used32. The reaction takes place immediately upon addition of a solution of hydrogen peroxide and selenium dioxide to a solution of a sulphide in methanol at room temperature. Yields of sulphoxides (Table 2) are in the range between 80 and 95%. It is most probable that perseleninic acid 19 is the true oxidizing agent. 

The structural features and the spectroscopic characteristics of the thiirene dioxide system (22) are of special theoretical interest since, on the basis of analogy with cyclopropenone (23), it is a possible nonbenzenoid aromatic system with all the physical and chemical implications involved. Aromatic and/or conjugative effects, if any, require transmission through the d-orbitals of the sulfur atom. 

Millero, F. J. (1995). Thermodynamics of the carbon dioxide system in the ocean. Geochim. Cosmochim. Acta 59, 661-677. 

Lactide/glycolide polymers have been investigated for delivery of agents in applications outside the pharmaceutical field. For example, the microbiocidal properties of chlorine dioxide disinfectants have been improved by formulating a long-acting chlorine dioxide system based on lactide/glycolide copolymers. Blends of microspheres based on 50 50 and 87 13 copolymers were developed to afford the release of chlorine dioxide over several months (114). 

SUNETAL. Spectroscopy of Metal-Titanium Dioxide Systems... 

Conjugation of the 7t-electrons of the carbon-carbon double bond with the LUMO sulfur 3d-orbitals would be expected to stabilize the Hiickel 4n -I- 2 (n = 0) array of n-electrons in the thiirene dioxide system. No wonder, therefore, that the successful synthesis of the first member in this series (e.g. 19b) has initiated and stimulated several studies , the main objective of which was to determine whether or not thiirene dioxides should be considered to be aromatic (or pseudo-aromatic ) and/or to what extent conjugation effects, which require some sort of n-d bonding in the conjugatively unsaturated sulfones, are operative within these systems. The fact that the sulfur-oxygen bond lengths in thiirene dioxides were found to be similar to those of other 802-containing compounds, does not corroborate a Hiickel-type jr-delocalization... 

The preparation and investigation of the thietane oxide system (5a) is largely associated with stereochemical and conformational studies . The investigation of the thietane dioxides (5b) is substantially related to the chemistry of sulfenes , the [2 -I- 2] cycloaddition of which with enamines is probably the method of choice for the synthesis of 5b . The study of the thiete dioxide system (6) evolved, at least in part, from the recognition that the unstable thiete system 183 can be uniquely stabilized when the sulfur in the system is transformed into the corresponding sulfone , and that the thiete dioxide system is very useful in cycloadditions and thermolytic reactions. The main interest in the dithietane oxides and dioxides (7) appears to lie in the synthetic challenge associated with their preparation, as well as in their unique structural features and chemical behavior under thermolytic conditions . ... 

The existence or nonexistence of conjugative effects involving the sulfone group in thiophene dioxides (a problem analogous to that in thiirene oxide and dioxide systems ) has been the subject of many studies resulting, nonetheless, in no unequivocal conclusion . 

A long-range proton coupling, which was found to be transmitted by a sulfone group in thiolane dioxide systems , is apparently facilitated by a nonbonding p-orbital on one of the sulfone oxygen atoms. This phenomenon is of interest for saturated cyclic systems. 

The [2 + 2] photodimerization of a, j8-unsaturated sulfones is correctly viewed as a photoreaction of alkenes, rather than the sulfone group, and this aspect has been reviewed recently by Reid, as part of a wider survey of the photoreaction of O- and S-heterocycles. The topic continues to attract considerable interest and a few recent examples, as well as some synthetic applications, will be discussed here. Much of the photodimerization work has been carried out on the benzo[fc]thiophene (thianaphthene) 1,1-dioxide system. For example. Porter and coworkers have shown that both 3-carboxybenzo[i]thiophene 1,1-dioxide (65) and its methyl ester give only the head-to-head (hth), anti dimer (66) on irradiation in ethanol. In a rather unusual finding for such systems, the same dimer was obtained on thermal dimerization of 65. Similar findings for a much wider variety of 3-substituted benzo[fi]thiophene 1,1-dioxides have been reported more recently by Geneste and coworkers . In the 2-substituted analogs, the hth dimer is accompanied by some of the head-to-tail (htt), anti dimer. The formation of the major dimer appears to proceed by way of an excited triplet and the regiochemistry observed is in accord with frontier MO theory. 

The ACTIV-OX system has been developed to meet the needs for a safe and controllable chlorine dioxide system for application in small water using systems. The system instantaneously delivers over 90% of the available chlorine dioxide at a pH of 4 compared to other systems which require lower pH and or longer reaction times (Fig 1 and 2). 

The ACTIV-OX chlorine dioxide system evaluated in this trial overcomes many of the problems associated with chlorine dioxide for the small water user. A chlorine dioxide precursor solution and a dilute acid solution are mixed in a 1 1 ratio immediately prior to injection into the water to be treated. The dose rate of chlorine dioxide is controlled by water meter signal to two proportioning pumps. The mixing of the two chemicals immediately produces a chlorine dioxide solution which is diluted to the required strength by injection into the water to be treated (Fig 3). 

The assessment of the performance of the new chlorine dioxide system was carried out over a continuous period of 39 weeks. 

The newly developed ACTIV-OX chlorine dioxide system has effectively delivered continuous low levels of chlorine dioxide which were effective in controlling Legionella in a hot and cold water system without the need for prior disinfection. 

Errington, J. R., Prewetting transitions for a model argon on solid carbon dioxide system, Langmuir 2004, 20, 3798-3804... 

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