All You Need to Know About A Mass Flow Controller

All you need to know about a mass flow controller


  1. Introduction
  2. What is a mass flow controller?
  3. What is a mass flow controller used for?
  4. Types of mass flow controllers
  5. How to use a mass flow controller?
  6. Conclusion


In this article, you will find out about mass flow controllers. These devices are used in many industries to keep the processes going the right way.

What is a mass flow controller?

A mass flow controller is a device that is used to measure & control the flow of fluids. Mass flow controllers are designed as well as calibrated to control a specific type of fluid (gas or liquid) at a certain range of flow rates. Typically, these devices are operated in the range from 10% to 90% of their full scale for the most accurate results.

Mass flow controller: Structure & Working Principle

Mass flow controller structure and working principle

A mass flow controller has a flow rate measurement section that consists of a flow rate sensor, flow rate control valve, bypass, as well as special circuitry (which includes a CPU with a driver/receiver, D/A - A/D converter, valve driver circuit and there is also an A/D converter). A piezo actuator is stable and it doesn’t generate heat. 

From an inlet joint, the gas is input and then it is divided. The gas flows over a bypass & a flow rate sensor. The mass flow rate of the gas is measured by the sensor. Then, the flow rate is modified by the flow rate control valve. The difference between the flow rate output signal & the flow rate that is received from the external flow rate setting signal is zero. A loop circuit of the mass flow controller ensures stable flow rate control. In case of ambient temperature or secondary pressure changes, the flow rate is instantly corrected.   

What is a mass flow controller used for?

Mass flow controllers are used in a wide range of applications. Let’s consider some of them. In the semiconductor industry, they are used for measuring and controlling the gasses used in the semiconductor chip-making process, for example, in chemical vapor deposition, backside water cooling, and more. 

Mass flow controller in semiconductor industry

In the food and beverage industry, among other tasks, mass flow meters are used to measure & control the dryer airflow rates. 

Mass flow controller in food and beverage industry

These devices also come in handy when packing snacks, for example, to measure the nitrogen injection flow rates of the packaging machinery and to check for leaks as well. 

Mass flow controller in packaging

Mass flow controllers are also irreplaceable in the pharmaceutical industry, for instance, they are used to control the process of pill coating. The airflow rate to a pill coater should be uniform so that product consistency is ensured. A mass flow meter helps to determine if the flow has dropped below the required level. 

pharmaceutical industry

Types of mass flow controllers

Let’s take a closer look at some of the types of mass flow controllers. How do mass flow controllers work? They differ depending on the mass flow sensor technology used in the device. 

Thermal mass flow controllers utilize the heat capacity of the fluid in order to control its mass flow rate. Such controllers introduce a known heat amount into the flowing stream or maintain a probe at a constant temperature and measure the required energy. As the thermal properties of the gasses are different, thermal mass flow controllers need to be calibrated for each type of gas.

Differential pressure mass flow controllers as the name implies, utilize differential pressure technologies. Please note that additional pressure, as well as temperature sensors, should be used and density correction factors should be assumed. When it comes to differential pressure sensing, only the data that is relatable to volumetric flow is provided. That’s why additional temperature- & pressure-dependent density correction factors are required to convert to a standardized mass flow rate.

Coriolis mass flow controllers use a principle that involves using a tube that is energized by a fixed vibration. The fluid passes through the tube and the mass flow momentum changes the tube’s vibration. It is a phase shift. From it, a linear output is obtained that is proportional to the flow. It is worth mentioning that the Coriolis method can be applied to both liquids and gasses.

How to use a mass flow controller?

Please note that mass flow controllers must be used by professionals only. Incorrect actions may put your and other people’s lives and health at risk. Read carefully the instructions provided by the manufacturer of the device you are going to use.

To understand how to use a mass flow controller, there are a few simple steps. Here is a description of a basic start-up operation.

Before using your mass flow controller, it should be installed and connected the right way.

1. Plug the AC to DC adapter into the power jack of the device.

How to use a mass flow controller

2. The device turns on. In this example, we have a mass flow controller that comes preset for air service. If you need to change to another gas, go to the menu and select the option you need. Let’s set the unit for helium service.

How to use a mass flow controller

3. Press the setpoint button to set the mass flow controller for 50 SCCM He.

How to use a mass flow controller

4. Press the Select Digit button to select the digit.

How to use a mass flow controller

5. After that, press the Set button.

How to use a mass flow controller

6. Now, on the display, there will be 50 SCCM He.

How to use a mass flow controller

7. To totalize the flow, press the Total/Menu button.

How to use a mass flow controller

8. Then, press the Reset button.

How to use a mass flow controller

9. Press the Main button to return to the main display.

How to use a mass flow controller

10. To stop the flow, press the Setpoint button.

How to use a mass flow controller

11. Now, press the Clear button.

How to use a mass flow controller

12. The display is clear. Press the Set button. Otherwise, the device will continue to operate.

How to use a mass flow controller

13. Now we see that the setpoint is at zero and the flow is at zero as well.

How to use a mass flow controller

14. To turn your mass flow controller off, just unplug the AC to DC adapter.

How to use a mass flow controller

For more details, check the user’s manual that goes with the exact model you are using.


Now, after reading this article, you know what a mass flow controller is, its components and operating principle, and also what types of these devices there are. In addition, you understand how to use a mass flow controller. On Mega Depot, there is a wide range of mass flow controllers for gasses. Get the right device for your application!

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