Gas tests

Applicability of Semiconductor Gas Sensors Research into the applications of this type of sensor has mainly been concerned with measuring carbon monoxide concentration in flue gases. Tests show that sensors follow the concentration of carbon monoxide in the flue gas. Improvement in sensor performance has resulted with the introduction of a catalytic additive (palladium or... 

Top width Ipm] Bottom width Ipm] Depth [mm] Hydraulic diameter dh [pm] Length L [mm] L/A Gases tested... 

The removal efficiency was quite good. The first gases tested had about f% H2S in a H2/N2 carrier over 98% was removed as shown in Fig. 25. The dashed lines in this figure are calculated, incorporating the effect of back-leakage through cracks in these first crude membranes. 

In an ideal situation the parameters used to define furniture should be ignition resistance and the rate of generation of heat, smoke and toxic gases. Tests to do this with actual or mock-up full sized furniture are not yet available as final specifications but the Nordtest (28) and NBS furniture calorimeters (29) represent scientific methods while room/ corridor rigs, typically UK DOE PSA FR5 and 6 of 1976 (5) (6) were originally used but are less satisfactory from a scientific point of view. The Californian (30) and Boston tests (31) for public area furniture are essentially simple room tests and are similar in principle to DOE, PSA, FR5 and 6 although the latter do not have pass/fail criteria. Bench scale rate of heat release tests include the NBS cone (29) which, with a code of practice represent a possible alternative but the rate of burning of... 

Table III is a list of gases which might interfere with an NOp analysis. Of all the gases tested, only H2S and S02 had a significant response oxidation currents were observed for both species. Neither gas gave a signal which was constant with time.

Flammability of Liquids, No. 340, Underwriters Laboratories Northbrook, 111., 1972 Flame Arresters, No. 525, 1973 Flammable Liquid Dispensing, No. 1238,1975 Group Classification of Flammable Liquids and Gases, Test Report MH8593, 67C2889,1967. 

These generalizations are illustrated in Fig 20 (from Ref 40), which also shows that 02 and mixts of 02 and N2 sensitize PETN, while all other gases tested desensitize it to shock. Note that shock amplitude in Fig 20 is given in terms of barrier thickness, ie, the thicker the barrier the more shock-sensitive the PETN-gas combination... 

It is very difficult to ascertain the quantitative effect of a waste stream interacting with the combustion zone without test data. In some cases, waste gases interacting with the burner flame may be beneficial in achieving reduced pollutant emissions. In other cases, the waste gas may act to quench or reduce the rate of oxidation reactions in the flame and inhibit destruction of the waste gases. Testing can be a very valuable tool when evaluating how best to introduce waste gas into a thermal oxidizer. 

The pump has a consistent speed for gases tested, as presented in Fig. 3. 

Operating at cold-plate temperatures of 18°K or below, pump operation is not affected by partial pressure of gases tested. 

Sensor temperature vs sensor conductance of the sensor when a sine wave was applied to the heater without the second harmonic (dashed line) and with the second harmonic (solid line) with a phase shift of (1) 0 rad, (2) kI2 rad, (3) jc rad, (4) 3%I2 rad. The sample gases tested were 1000 ppm of (a) ethanol, (b) ethane, (c) toluene. From N a kata et al. (2006). 

Material Type Fiber diameter (nm) Gases tested T (°C) Detection limit References... 

Type of metal oxide Gases tested Multiple or single nanowire Cross-section, diameter (nm) Working temperature (°C)... 

H2, CO2, and hydrocarbons (Figure 17d). The solid shows highly selective sorption for CO2 but little or no sorption for other gases tested. The sorption isotherm of CO2 follows a typical type 1 curve, and the uptake is saturated at 10 atm at23°C. 

Recommended fuel cell test conditions include the use of pure hydrogen and air/oxygen, humidified at 80 °C to assure 100 % relative humidity at an anode stoichiometry of 2 and cathode stoichiometry of 9.5. Both electrodes should be maintained at a backpressure that results in a 1.0 bar partial pressure of the gases. Testing is typically carried out a cell temperature of 80 °C. 

Gas permeability measurements were performed on the blended films as presented in Fig. 33.14. The blend shows a definite increase in permeability for all gases tested, relative to polyimide and the base form of polyaniline [60J. Ordinarily, there is an inverse relationship between permeability of two gases and the separation factor for those gases [61-64]. However, this blend does not hold to this axiom. Figure 33.15 illustrates the separation factors for the blend and the homopolymers. The separation factors for the blend are comparable to those of polyaniline (as-cast) for H2/N2 (a = 200) and O2/N2 (a = 9) and closer to that of polyimide for CO2/CH4 (a = 58). Thus, this blend appears to have achieved an improved combination of properties compared to its parent polymers, with enhanced permeability and good selectivity. 

Among other data of importance, these authors noted that tests with poly(3-octyl thiophene) and poly(thienylene vinylene) showed no separation activity (i.e. no selectivity between gases) and that doping of the P(ANi) with tosylic anhydride rather than nitric or hydrochloric acids yielded enhanced permeabilities for all gases tested. 

While most solid-polymer mixed-matrix membranes rely on sieve micropores to generate high selectivities within the membrane by discriminating between gas penetrants, mesoporous molecular sieves have been studied as well. These mesoporous sieves arc used to increase permeabUity in mixed-matrix membranes, instead of enhancing selectivity. Mesoporous MCM-41 incorporated into a polysulfone matrix improved membrane permeability for aU gases tested. The selectivity of pure polysulfone was maintained, as expected. Mesoporous sieves are an excellent material for highly selective polymer membranes that require increased productivity however, nanoscopic-scale crystals will probably be required to enable accommodation within the submicron selective layer typical for high-performance asymmetric membranes in use today. 

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