This question gets asked frequently due to concerns about validating data and measurement using inline or laboratory viscometers. The answer ultimately depends on how critical the measurement is and the type of viscometer used in your application.
There are many different types of viscometers, including oscillating piston, rotational, vibrational, falling ball, and oscillatory, just to name a few. Rotational viscometers use mechanical parts which can accumulate debris or wear down with time, similar to brakes in your vehicle.
It is recommended that a system checkout be performed on an annual basis for oscillating piston viscometers, allowing one to verify proper operation within our 1% accuracy specification. This can be performed using a few milliliters of viscosity standard fluids in a few minutes. Generally, no changes are necessary. There are no mechanical or electrical wear in the oscillatory piston technique, so recalibration of this type of viscometer is rarely needed. In the rare instance that an analyzer it is determined to be out of specification, a two-point calibration can be performed by the user, on-site using widely available calibration standards.
Based on the number of variables to consider, it is difficult to state how often your viscometer should be calibrated. However, based on the history and our experience using oscillating piston technology, it is simply recommended to check it in the once a year and performing a field calibration when necessary. Annual checks of any instrumentation will minimize down time and costs associated with factory calibrations needed for different viscometer sensing technologies.
Need help finding viscosity standards? We’re happy to help! Please contact us at sales@cambridgeviscosity.com for assistance.