Centrifugal homologous

Two different size pumps are said to be geometrically similar when the ratios of corresponding dimensions in one pump are equal to those of the other pump [Holland and Chapman (1966)]. Geometrically similar pumps are said to be homologous. A set of equations known as the affinity laws govern the performance of homologous centrifugal pumps at various impeller speeds. 

Consider a centrifugal pump with an impeller diameter D operating at a rotational speed N2 and developing a total head Ahx. Consider an homologous pump with an impeller diameter D2 operating at a rotational speed N2 and developing a total head Ah2. 

Equations 4.24 to 4.27 are the affinity laws for homologous centrifugal pumps. 

Middle oils, or creosote oils, generally are the fraction from 200 to 250°C, which contain naphthalene, phenol, and cresols. The naphthalene settles out on cooling, is separated by centrifuging, and is purified by sublimation. After the naphthalene is removed, phenol and other tar acids (phenol and its homologs) are obtained by extraction with 10% caustic soda solution and neutralization, or springing by carbon dioxide. These are fractionally distilled. 

Fig. 3 Appearance of fragments protected from micrococcal nuclease digestion following incubation of Xenopus sperm chromatin in homologous egg extract. Sperm nuclei were used without extract incubation (lane 2) or following incubation of 50 ng DNAZ/il egg LSS for 3 min (lane 3), 10 min (lane 4), 30 rain (lane 5), or 120 min (lane 6). Samples were diluted and the sperm nuclei were isolated by centrifugation. The samples were digested with micrococcal nuclease for 1 min and the DNA purified and separated by a 1.4% Tris-borate-EDTA agarose gel. Lane I shows molecular weight markers in lOO-base-pair increments.

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