Anisokinetic sampling, effect

The effect of anisokinetic sampling is plotted in Fig. 8.4. This analysis indicates that isokinetic sampling is not necessary when very small particles are sampled. Sometimes, in an effort to be precise,... 

Figure 8.4 Effect of anisokinetic sampling on measured sample concentration.

As indicated before, previous detailed studies of particulate formation and emission processes in automobile engines and exhaust systems have been done using probes which extracted a (hopefully) representative sample of the exhaust gas that was subsequently analyzed for various particulate properties (5). Similar techniques have been used in the most recently developed systems to measure the amounts of particles emitted from auto exhaust. Such sampling techniques, however, suflFer from inherent disadvantages in that they interfere with the hot flow particulate processes and have an unknown effect on the particulates as they flow through the system to an exterior point of analysis. This problem can also be compounded by several phenomena anisokinetic sampling, deposition of particulates in the sampling system, or condensation caused by temperature drops. 

Figure 12. Effect of Anisokinetic Sampling on Particle Concentration.

Zhu, C., Yu, T., and Huang, D., "Numerical Study of Effect of Velocity Slip on Isokinetic/Anisokinetic Sampling of Gas-Solid Flows", Int. Symp. on Multiphase Fluid, Non-Newtonian Fluid and Physicochemical Fluid Flows 97 Beijing, Oct. 7-9, Beijing, China, 1997. 

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