A Brief Introduction to Gas Coriolis Flowmeters

When fluid flows through a rotating tube, it exerts a force on the tube wall. This force, discovered by Coriolis in 1832 while studying turbines, is referred to as the Coriolis force. In 1977, the founder of Micro Motion, an American company, developed the world's first practical gas Coriolis flowmeter based on this principle. A gas Coriolis flowmeter is based on the Coriolis force. The sensor contains two parallel flow tubes, with a drive coil in the middle and detection coils at both ends. When an excitation voltage provided by a transmitter is applied to the drive coil, the vibrating tubes vibrate back and forth. When the fluid medium in an industrial process flows through the sensor's vibrating tubes, it generates a Coriolis force effect on the tubes, causing torsional vibration. The detection coils at both ends of the tubes generate two signals with different phases. The phase difference between these two signals is proportional to the mass flow rate of the fluid passing through the sensor. A computer calculates the mass flow rate through the vibrating tubes. Different media flowing through the sensor have different main vibration frequencies of the vibrating tubes, which are used to calculate the medium density. A platinum resistance resistor mounted on the sensor's oscillating tube indirectly measures the medium's temperature.

A gas Coriolis flowmeter directly measures the mass flow of the medium passing through the flowmeter, and can also measure the medium's density and indirectly its temperature. Because the transmitter is an intelligent instrument based on a single-chip microcomputer, it can derive over a dozen parameters based on the three basic quantities mentioned above. Gas Coriolis flowmeters offer flexible configuration, powerful functionality, and a high cost-performance ratio, making them a new generation of flowmeters.

Flowmeters measure mass flow in pipelines. When the measured fluid is subject to significant fluctuations in parameters such as pressure and temperature, measuring only volume flow can result in significant measurement errors due to changes in fluid density. In positive displacement and differential pressure flowmeters, the density of the measured fluid can vary by 30%, resulting in a 30-40% error in flow measurement. With increasing automation, many production processes are placing new demands on flow measurement. Chemical reactions are controlled by the mass (not volume) of the raw materials. The heating and cooling effects of steam and air flows are also proportional to mass flow. Strict control of product quality, accurate cost accounting, and fuel quantity control for aircraft and missiles all require precise flow measurement. Therefore, the gas Coriolis flowmeter is an important flow measurement instrument.