Premixed-type luminous flame

The design of the premix burner shown in Figure 10 also presents a number of other advantages and disadvantages as compared with the total consumption type. The flame is not very luminous, and flicker and turbulence are quite low, so that for many elements the flame contributes no apparent noise to the output (Figure 8). Furthermore, there is rather little dependence of absorption upon sample flow rate. This is of benefit in two ways. First, the length of sample capillary, and its depth of immersion in the solution, are not very critical, so that samples can be aspirated from any vessel. For total consumption burners, by contrast, Petri dishes or very small sample containers are often recommended. Second, viscosity interferences caused by variations in sample concentration are minimized, though not eliminated. In the Perkin-Elmer burner, when the sample flow rate is cut by a factor of 2, absorption is reduced by approximately 4%. 

There are four types of burners, namely, standard, premixed, staged air/fiiel (low NO ), and next generation (ultralow NO ). Standard gas and premixed burners have luminous flames. The eombustion reaction occurs within the visible flame boundaries. Ultralow NO c burners have nonluminous flames, and much of the eombustion reaetion is not visible. 

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