How are pharmaceutical manufacturers measuring viscosity?
There are many ways that viscosity can be measured, such as capillary, vibration, falling object, rotational, even mixer or pumping force. These methods have very different accuracies and benefits, and may work well for process monitoring or control, but may not be in agreement with laboratory or analytical requirements. In general laboratories require a more scientifically correct measurement, while process control requires a stable, repeatable signal. Process measurements are made in-line or off-line. A bench-top viscometer has generally been used for off-line measurements wherein a sample of the process fluid is drawn and tested under controlled conditions (temperature, shear history, shear rate, etc.). In-line viscometers are immersed in the process stream and measure continuously under process conditions. The demands of these two environments are so different that it is unlikely that the same equipment can be used for both or that the exact same results will be generated. However,
