Capability Studies of Densitometers and Densitometry

Since densitometric data is used in SPC, Statistical Process Control, it is essential to know the capability of densitometry as a measurement process. Also, knowing the inherent variability and stability of process components can lead to improved data by optimizing operating and control procedures. Studies of commercial densitometers are used to illustrate the process of resolving components of systems variability. Identical experiments can be applied to colorimeters and spectrophotometers since they are closely related instruments. The examples illustrated do not represent an endorsement or condemnation of the instruments by either PSI ASSOCIATES or the ANSI Subcommittee IT2-28. One fact, however, is clear all densitometers are not created equal.