Gas Pressure Monitoring Research Articles

Study of photocatalytic decomposition of hydrogen peroxide over ramsdellite-MnO2 by O2-pressure monitoring

Abstract The catalytic and photocatalytic activities of ramsdellite type manganese oxide, R-MnO2 were studied from the initial rate of decomposition of H2O2 in aqueous solution. The kinetic study was followed by the production of O2 via gas pressure monitoring (O2-monitored method), in the dark and under visible light irradiation (λ ≥ 400 nm), at 20 °C. Experimental data showed that the rate of H2O2 decomposition, under visible light irradiation and in the dark, obeys the first order kinetic law. While in the dark the H2O2 decomposition rate by mass unit was around 6.88 mmol g−1 s−1, under visible light irradiation the H2O2 decomposition rate achieved a maximal value of 15.13 mmol g−1 s−1. The increase in the H2O2 decomposition, by effect of the visible light, was observed in ranges of catalyst concentrations from 16 to 374 mg L−1. These results reflect the potential of R-MnO2 as a photoactive catalyst, being a consequence of presumed photoreduction of Mn4+centers.

Essential features of optical processes in neon-buffered submicron-thin Rb vapor cell

A new submicron thin cell (STC) filled with Rb and neon gas is developed and comparison of resonant absorption with STC containing pure Rb is provided. The effect of collapse and revival of Dicke-type narrowing is still observable for the thickness L = lambda /2 and L = lambda , where lambda is a resonant laser wavelength 794 nm (D(1) line). For an ordinary Rb cm-size cell with addition of buffer gas, the velocity selective optical pumping/saturation (VSOP) resonances in saturated absorption spectra are fully suppressed if neon pressure > 0.5 Torr. A spectacular difference is that for L = lambda , VSOP resonances are still observable even when neon pressure is > or = 6 Torr. Narrow fluorescence spectra at L = lambda /2 allow one to realize online buffer gas pressure monitoring. A good agreement with theoretical model is observed.

光ファイバガス密度センサを用いたGILのガス圧監視システム

The authors have developed a fiber-optic gas pressure monitoring system with new gas density sensors for detecting the leakage of insulation gas of gas-insulated transmission lines (GILs). In this system, the gas pressure of over one hundred gas compartments can be monitored with several optical fibers and without electric power supply to the sensors. This simple and highly reliable system enables speedy gas leakage detection, allowing one to take appropriate measures before reaching its critical pressure. The developed sensor makes a mechanical bend of an optical fiber when there is gas leakage, and causes optical transmission loss as the detected signal. Using a conventional optical time domain reflectometer with these sensors, a multi-point sensing system can be constructed. In this paper, the authors report the principle of this sensor and the design of the monitoring system for Japan's Shinmeika-Tokai GIL.

Breathing system gas pressure monitoring and venting, ventilator monitors and alarms.

Breathing system gas pressure monitoring and venting, ventilator monitors and alarms.