INTRODUCTION

This is one of the most important recent meter developments, and its application in the next few years is likely to impinge on many areas of industry. Its importance is recognized by the main national and international advisory bodies (cf. Mandrup-Jensen 1990 who described initial work in Denmark on pattern approval and ISO developments).

BACKGROUND

Plache (1977) makes the interesting point that mass cannot be measured without applying a force on the system and then measuring the resulting acceleration. This is a point that I have long considered a possible requirement, and it is certainly supported in the Coriolis meter.

Possibly the first application of the Coriolis effect for mass flow measurement was proposed by Li and Lee (1953). The meter is shown in Figure 17.1. The T-piece flow tube rotated with the outer casing and was linked to it by a torque tube. As the flow increased, so the T-piece experienced a displacing torque due to the Coriolis acceleration, and this was measured from the displacement of the T-piece relative to the main body.

In the Li and Lee meter, the liquid was forced to move radially, and therefore a force was applied to it through the tube. This force, in turn, was balanced by an equal and opposite one applied by the liquid to the tube. The force caused the tube to twist, and the small rotation was sensed to obtain the mass flow rate.