Working Principle of Liquid Mass Flow Controller

The principle of the laminar differential pressure mass flowmeter is based on Hagen-Poiseuille’s law.

It is mainly divided into two steps:

The first step is to establish a laminar state: The laminar flow element inside the flowmeter transforms the fluid in the turbulent state into a laminar state, so that the fluid presents laminar motion and provides stable conditions.

The second step is based on the linear correspondence between the pressure difference and the flow rate. According to Poiseuille’s law, the pressure difference (△p) in the laminar state is proportional to the volume flow rate (Q): Q=k·△p/μ (K is the structural constant of the laminar flow element, μ is the fluid viscosity, when the fluid viscosity is stable, the pressure difference directly reflects the mass flow rate)

The most typical laminar differential pressure mass flow meter contains five core components:

1. Laminar flow element: transforms the passing fluid from a turbulent state to a laminar state
2. Pressure difference sensor: monitor the pressure difference signal at both ends of the laminar flow element and transmit it .
3. Pressure sensor: measures the pressure value of the measured fluid.
4. Temperature sensor: measures the temperature value of the measured fluid
5. Hardware circuit board: convert the pressure difference signal into a mass flow value and output a standard signal.

Workflow: Convert the fluid from a turbulent state to a laminar state. Then measure the pressure difference signal at both ends. The sensor collects the signal and calculates the mass flow rate through the ideal gas state equation.

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