Case Study: Increased Backpressure Improves Promass Measurement In Difficult Applications

Viscous liquids tend to hold entrained air for long periods of time, and air bubbles in a liquid can cause unstable measuring conditions for a Coriolis meter when the volume of air gets too high.

Challenge
It has long been known that among the most difficult applications for a Coriolis meters are viscous liquids with entrained air. Viscous liquids tend to hold entrained air for long periods of time, and air bubbles in a liquid can cause unstable measuring conditions for a Coriolis meter when the volume of air gets too high. A relatively large flow meter is often selected in order to minimize pressure drop when a viscous liquid needs to be measured. Accuracy can then be compromised by the resulting "oversized" meter, because any zero point problems for a Coriolis meter are more visible in the low part of a meter's overall range. A recent starch slurry application at a major soup producer illustrates this typical problem, and also demonstrates how backpressure can improve the measuring results.