MASS FLOW METERS :
The continuing need for more accurate flow measurement is mass related process(chemical reactions, heat transfer etc) has resulted in the development of mass flow meters. Various designs are available, but the most commonly used one is coriolis meter.Its operation is based on the natural phenomenon called the coriolis force. Let's have a look at Coriolis mass flow meter which explained below.
CORIOLIS METER :
Coriolis meters are true mass flow meters measure the mass rate of flow directly as compared to volumetric flow rate. In volumetric flow meter the mass flow rate is determined by using the formula,
where QM-mass flow rate,
QV- volume flow rate;
P- fluid density
The working principle of Coriolis meter is based on Newton’s second law of motion F=m*a. Each sensor consists of one or two tubes enclosed in sensor housing.
The flow tube driven by an electromagnetic coil located at the centre of the bend in the tube. The fluid being measured flow through the sensor tube which is vibrated at its natural frequency by an electromagnetic device with amplitude of less than 1mm and frequency of 80 Hz.
When fluid is moving through the sensors tube, coriolis forces are induced in both inlet and outlet legs of the tube. These forces causes the flow tube to twist. The mass flow moving through the inlet legs of the flow tubes generate a coriolis force that resists the vibration of the flow tube.
As the mass flow moves through the outlet legs, the coriolis force adds to the vibration of the flow tube. It is in the opposite direction to the coriolis force between the inlet and outlet legs that result in the twisting motion that used to measure mass flow rate.