[en] A brief introduction is given on how the ozone layer formed and about the factors depleted ozone layer such as chloro bromo compounds and so on; then, it follows the processes which destroy the troposphere. The damaging effect of ultraviolet radiation is described. Finally,the action taken to reduce the depletion of ozone layer is presented

No abstract available

[en] We estimate a current direct radiative forcing due to CFC-12 of 0.18Wm^-2, which is likely to be the peak radiative forcing for CFC-12. Global measurements of CFC-12 show at present an almost negligible trend for CFC-12 and measurement in an industrialized region show evidence that the peak concentration is reached. It is expected that concentration of CFC-12 in industrialized regions begins to decline 1-3 years before the global concentration. Our radiative forcing calculations are based on a line-by-line model appropriate for simulation of global mean radiative forcing, including clouds and stratospheric temperature adjustment. The radiative forcing of 0.33Wm^-2/ppbv is close to earlier published results for this compound. New spectroscopic measurements for CFC-12 are performed and compared to previously published results

[en] This article presents dimensionless equations for the temperature dependence of the saturated liquid viscosity of R32, R123, R124, R125, R134a, R141b, and R152a valid over a temperature range of engineering interest. The correlation has the form Φ_Dⁿ= A +BT_D where Φ_D is the dimensionless fluidity (1/η_D) and T_D is a dimensionless temperature. n, A, and B are evaluated for each of the above refrigerants based on a least-squares fit to experimental data. This equation is found to provide an improved fit over those existing in the literature up to T_D = 0.8

[en] In our own domestic politics in the United States, examples of renunciation of a civilian technology that I can think of easily are the Supersonic Transport, where we made a social decision not to subsidize production of the 2000 mile per hour Boeing embodiment, and the related decision to begin restricting the use of chlorofluorocarbons (CFCs). We began doing the latter in the 1970s, more as a fallout of the Supersonic Transport debate than the self-standing concern it has become. We now have global arrangements to cut back on CFCs, and it would appear that the ones that we have had are going to be tightened. Those are very unusual in the history of technology. it was not a vote of the people that caused inter-urban trams to go out of service. You can look at the history of Los Angeles and say there were some local votes of bodies that were manipulated to hasten the decline of them, but on the whole, technologies are not voted up or down by the people. This is not a plebiscitary thing. In polling, there is an implication that you are taking a sounding of the people and are acting as a result of that sounding. Perception is that everyone is pushing their button, and then you do something

[en] Results are presented from experimental studies of the destruction of chlorofluorocarbon (CF₂Cl₂) molecules in a methane-oxygen (air) gas mixture whose combustion is initiated by a high-current slipping surface discharge. It is found that a three-component CH₄ + O₂(air)+ CF₂Cl₂ gas mixture (even with a considerable amount of the third component) demonstrates properties of explosive combustion involving chain reactions that are typical of two-component CH₄ + O₂ mixtures. Experiments show the high degree of destruction (almost complete decomposition) of chlorofluorocarbons contained in the mixture during one combustion event. The combustion dynamics is studied. It is shown that the combustion initiated by a slipping surface discharge has a number of characteristic features that make it impossible to identify the combustion dynamics with the formation of a combustion or detonation wave. The features of the effects observed can be related to intense UV radiation produced by a pulsed high-current surface discharge

[en] The intended phaseout of the chlorofluorocarbons (CFCs) from commercial use required the evaluation of substitute materials for the testing for leak paths through both individual adsorbers and installed adsorbent banks. The American Society of Mechanical Engineers (ASME) Committee on Nuclear Air and Gas Treatment (CONAGT) is in charge of maintaining the standards and codes specifying adsorbent leak test methods for the nuclear safety related air cleaning systems. The currently published standards and codes cite the use of R-11, R-12 and R-112 for leak path test agents. All of these compounds are CFCs. There are other agencies and organizations (USDOE, USDOD and USNRC) also specifying testing for leak paths or in some cases for special life tests using the above compounds. The CONAGT has recently developed criteria for the suitability evaluation of substitute test agents. On the basis of these criteria, several compounds were evaluated for their acceptability as adsorbent bed leak and life test agents. The ASME CONAGT Test Agent Qualification Criteria. The test agent qualification is based on the following parameters: (1) Similar retention times on activated carbons at the same concentration levels as one of the following: R-11, R-12, R-112 or R-112a. (2) Similar lower detection limit sensitivity and precision in the concentration range of use as R-11, R-12, R-112 and R-112a. (3) Gives the same in-place leak test results as R-11, R-12, R-112, or R-112a. (4) Chemical and radiological stability under the use conditions. (5) Causes no degradation of the carbon and its impregnant or of the other NATS components under the use conditions. (6) Is listed in the USEPA Toxic Substances Control Act (TSCA) inventory for commercial use

[en] The liquid thermal conductivities of the CFC alternatives, HFC-125, and HCFC-141b measured by a transient hot-wire apparatus with one bare platinum wire are reported in the temperature ranges from 193 to 333 K (HFC- 125, CHF₂·CF₃) and from 193 to 393 K (HCFC-141b, CCl₂F-CF₃), in the pressure ranges from 2 to 30 MPa (HFC-125) and from 0.1 to 30 MPa (HCFC- 141b), respectively. The results have been estimated to have an accurancy of ±0.5%. The liquid thermal conductives obtained have been correlated by a polynomial of temperature and pressure which can represent the experimental results within the standard deviations of 0.49% for HFC-125 and 0.46% for HCFC-141b, respectively

[en] The U.S. Enrichment Corporation's production of isotopically enriched uranium depends solely on two plants which utilize the gaseous diffusion process. This process uses large quantities of CFC-114 as an evaporative coolant. CFC-114, however, will be phased out of production at the end of 1995 due to its potential to deplete stratospheric ozone. A search has been underway for substitutes for a number of years. The initial search (1988-89) for an ozone-friendly, commercially available, chemically compatible substitute yielded two candidates, FC-c318 (c-C₄F₈) and FC-3110 (C₄F₁₀). The intended mode of replacing coolant was to stage the new coolant into independent subsystems of the plants, so that some systems would continue to operate on CFC-114, and an increasing number would operate on the new coolant. During that changeover process, the possibility of coolant mixing arises in variety of scenarios. This work was intended to generate sufficient experimental information to be able to predict the vapor pressure of coolant mixtures over the range of operating conditions likely to be found in the diffusion plants. Specifically, vapor pressures were measured over the temperature range 322 to 355 K (120 degrees F to 180 degrees F) and over the full range of mole fractions for binary mixtures of CFC-114 with FC-3110, and of CFC-114 with FC-c318

[en] A multiparameter mixing approach, 'MIX', for determining oceanic anthropogenic CO₂ was used to reconstruct the industrial-era change in the ¹³C/¹²C of dissolved inorganic carbon ((delta)¹³C of DIC) along the 1992 165 deg E WOCE P13N section in the North Pacific Ocean. The back-calculation approach was tested against a known anthropogenic tracer, chlorofluorocarbon-11 (CFC-11), and also by reconstructing an ocean general circulation model's (OGCM) anthropogenic (delta)¹³C change. MIX proved accurate to ±10% against measured CFC-11, but only to ± ∼25% reconstructing the OGCM's (delta)¹³C change from 1992 model output. The OGCM's CFC distribution was also poorly reconstructed using MIX, indicating that this test suffers from limitations in the OGCM's representation of water masses in the ocean. The MIX industrial-era near-surface (200 m) (delta)¹³C change reconstructed from the WOCE P13N data ranged from -0.08% in the subtropics (15-30 deg N), to -0.06% in the tropics (10 deg N), and -0.04 to -0.02% north of 40 deg N. Depth-integrated changes along 165 deg E were -40%.m to -50%.m at low latitudes, and were smaller (-20%.m) north of 40 deg N. The MIX North Pacific (delta)¹³C change is consistent with the global anthropogenic CO₂ inventory of 118 ± 17 Pg from (delta)C*