Pumps selection criteria

However, it may be that low HRV is a better predictor of nonarrhythmic mortality than SCD. In DINAMIT (as discussed above), low HRV was a selection criterion for trial entry (26). That the decrease in arrhythmic death was offset by the increase in nonarrhythmic death may be due to the inability of HRV to discriminate between the mode of death. HRV may have been a marker of advanced hemodynamic disease and pump failure, rather than a marker for arrhythmic death. In the ALIVE trial, a low HRV increased the risk of all-cause mortality (HR 1.46, 95% Cl 1.1-1.94) but not arrhythmic mortality (68). Given these discrepant results, the role of HRV in prediction of SCD is unclear. 

Answer by Author A criterion for NPSH computation reliability is its repeatability when using a wealth of data. A three-thermocouple redundancy per measurement and the multiplicity of test runs pinpointed the temperatures selected. Then, by using equivalent vapor pressures, and by judiciously establishing pump inlet head losses, no erroneously-negative values of NPSH were realized. Since related suction specific speed values were neither imaginary nor infinite, and, because no hypothetical approaches were necessary to calculate their real values, the NPSH values were deemed reliable. 

The dimensions of plain steel pipes, their pressure ratings, and relative roughness are presented in Table 2-2. It is obvious that steel pipes are limited in pressure rating to 3000 psi. This criterion is essential when considering location of booster pump stations or chokes. In the case of slurry pipelines, the thickness of the pipes is selected on the basis of... 

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