Gas sampling tubes

Fig. 1.16. Gas-sampling tube. The tube is flushed with the reagent gas by opening to the reagent gas inlet and venting to a mineral oil bubbler. After several minutes, the flush is terminated by first closing the inlet stopcock, then the outlet stopcock. (This ensures that the pressure inside the tube equals the laboratory atmospheric pressure.) The laboratory temperature and pressure are then measured for use in calculating the amount of gas dispensed. Finally, the known quantity of reagent gas is dispensed to the reaction vessel by opening the inlet stopcock to inert gas. the outlet stopcock to the reaction vessel, and flushing the tube with inert gas for several minutes.

A gas sample is taken by refilling the gas collection bottle with water and leading the gas that is displaced by the water through the gas sample tube. 

The volume of gases formed in a reaction can be easily measured without exposure to air by means of a Toepler pump. Although automatic versions can be purchased commercially, a hand-operated one is described here for convenience. Figure 4.15 shows a schematic drawing of the Toepler pump. A flask containing an unknown amount of gases in solution is connected at stopcock A of the Toepler pump and gas sampling tubes are attached at stopcock D. The system is completely evacuated before use. Then... 

Realisation of the first approach - trapping and offline analysis - employs a miniature gas-sampling tube packed with a mixture of Tenax (molecular sieve) and Carbopak (activated charcoal) absorbent material. Such tubes are routinely used for environmental monitoring of hazardous industrial atmospheres whereby operators during the normal course of their duties carry a small tube (about the size of a pen) clipped to their clothes. A pump may be used to draw gas through the tube at a controlled rate and, at the end of the work period, the tube is sealed and sent for analysis. Heating the sorbent tube drives off the trapped material into a gas chromatograph for separation and quantification. 

The gap between autoclave wall and fuel element had a thickness of 1 or 2 mm, respectively. The experiments were performed at 22 or 55 C brine temperature. A gas plenum with a pressure gauge for continues measuring was located above the autoclave. Gas samples were taken with an attachable gas sampling tube to analyse the gas composition by gas chromatography and radio gas chromatography. 

Gasmaus gas collecting tube, gas sampling bulb, gas sampling tube Gasraum/... 

S ample Analysis. The fohowing procedure is used for sample analysis (/) after sample connections are made and the sample tubing purged for 30 minutes, the tubing is connected to the sampling manifold which serves to distribute sample gas to each of the analy2ers, and should analy2ers have specific pressure... 

Sampling from pneumatic conveyors parallels gas sampling. The exception is that soflds loadings can be as high as 50 kg of soHds per kg of gas. Commercially available samplers extract particles directly from a transport line. Fixed position samplers are mounted directly on the pneumatic conveyor pipe. Devices are available which extract samples from the product stream by the projection of a sample tube iato the flow. Particles impact on the tube and fill the open cavity. The tube is then withdrawn, and an internal screw discharges the collected material (20). In another model, the RX Sampler (manufactured by Gustafson) (29), samples are withdrawn usiag compressed air. 

Table 10.14 Thermal desorption of sorbed gas from sample tubes...

When the burner went out, the solenoid valve took a few see-onds to elose, and during this time some oil entered the furnaee. In addition, the line between the last valve and the furnaee may have drained into the furnaee. The flash point of the fuel oil was 65°C, too high for the oil to be deteeted by the eombustible gas deteetor. Even though the oil was vaporized by the hot furnaee, it would have eondensed in the sample tube of the gas deteetor or on the sintered metal that surrounds the deteetor head. 

The pressure of a gas sample can be measured in a device similar to a barometer, called a manometer. Figures 4-2B and 4-2C show two types. Figure 4-2 B shows a closed-end manometer. Here the downward pressure exerted by the column of mercury is balanced by the pressure of the gas sample placed in the flask. The gas pressure is, in the example shown, 105 mm. As in the barometer, only mercury vapor is present in the right-hand tube. 

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