Compressor oils can create unique challenges when trying to measure viscosity. Dissolved gases from refrigerants, in particular, tend to bubble out when these oils are measured using traditional viscometers. This can create errors in the measurement, typically causing readings to be much lower than they should be.
One way to get around this problem is to allow the oil sample to degas before making the viscosity measurement. One major drawback is that it can take several hours or up to a day for the oil to degas sufficiently. Fortunately there's a better way.
The Spectro Scientific Q3000 viscometer has a unique split cell design that allows oil to flow through the measurement cell uninterrupted by outgassing. The gas in the sample is dissipated out the sides of the cell, rather than bubbling up through the sample as it is being measured. In this brief video, Dan Walsh, Director of Applications and Technical Services, explains how this works.