Minimum Running Clearances

The minimum required NPSH on the pump curves is normally determined using water at 60°F with the discharge line fully open. However, even though a pump will run with a closed discharge line with no bypass, there will be much more recirculation within the pump if this occurs, which increases local turbulence and local velocities as well as dissipative heating, both of which increase the minimum required NPSH. This is especially true with high efficiency pumps, which have close clearances between the impeller and pump casing. 

Precision is a fundamental measure of assay performance and it should be assessed whenever possible [55]. This will allow a minimum understanding of how much confidence can be placed in the analytical data. In fully characterized assays designed to support definitive nonclinical and clinical studies, between-run and within-run assay precision of 15% or less (20% at the quantitation limit) is acceptable. Because of the shortened time scale for assay development and characterization in discovery these guidelines are excessively restrictive. Precision values of 20 to 30% are acceptable, as these are still less than intersubject variability associated with many nonclinical experiments. With this level of imprecision, data quality is sufficient to answer fundamental scientific questions such as relative levels of drug absorption, relative values of absolute bioavailability, and relative degree of drug clearance. 

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