Pumping of gases

The type of equipment best suited for the pumping of gases in pipelines depends on the flow-rate, the differential pressure required, and the operating pressure. 

Other more exotic mechanisms include chemical reactions in gases, high-voltage electron beam pumping of gases, and direct current injection across the junction of a semiconductor laser. 

The type of equipment best suited for the pumping of gases in pipelines depends on the flow rate, the differential pressure required, and the operating pressure. In general, fans are used where the pressure drop is small. Axial-flow compressors are employed for high flow rates and moderate differential... 

A diffusion mechanism is also used in dialysis as a means of separating colloids from crystalloids. The rate of diffusion of molecules in gels is practically the same as in water, indicating the continuous nature of the aqueous phase. The diffusion of gases into a stream of vapour is of considerable importance in diffusion pumps. 

A third pumping method (Fig. Ic) uses an electrical discharge in a mixture of gases. It relies on electronic excitation of the first component of the gas mixture, so that those atoms are raised to an upper energy level. The two components are chosen so that there can be a resonant transfer of energy by collisions from the upper level of the first component to level 3 of the second component. Because there are no atoms in level 2, this produces a population inversion between level 3 and level 2. After laser emission, the atoms in the second component return to the ground state by collisions. 

Pumping of liquids. Compression of gases Mixing (solids, liquids, gases possibly multiphase) Atomization, dispersion... 

Detector tubes/pumps are screening instruments which may be used to measure hundreds of organic and inorganic gases and vapors or for leak detection. Some aerosols can also be determined. Detector tubes of a given brand are to be used only with a pump of the same brand. 

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