1. Concept of mass flow meter and mass flow controller

Mass flow meter, namely Mass Flow Meter (MFM), is an instrument for accurately measuring gas flow. Its measured value is not inaccurate due to temperature or pressure fluctuations, and does not require temperature and pressure compensation.

The mass flow controller (MFC) not only has the function of mass flow meter, but also can automatically control the gas flow, that is, the user can set the flow as required, and MFC automatically keeps the flow at the set value, even if the system pressure fluctuates or the ambient temperature changes, it will not deviate from the set value. The mass flow controller is a gas flow stabilizing device, which can be set manually or connected with a computer for automatic control.

In short, the mass flowmeter only measures but does not control. The mass flow controller is equipped with a control valve, which can measure and control the gas flow.

2. Mass flow meter

The gas mass flow unit is generally expressed in SCCM (Standard Cubic Centrimeter per Minute) and SLM (Standard Liter per Minute), that is, standard milliliter per minute and standard liter per minute. This means that the flow indicated by this instrument under different service conditions is the flow under standard conditions. This is an important difference between this instrument and other flow meters, and also the difference between SCCM and SLM from Ml/min and L/min.

If you need the mass flowing in unit time (such as g/min), you can look up the gas density in standard state, and then multiply it.

3. Main advantages of mass flow meter/mass flow controller

(1) Direct measurement of gas mass flow

The thermal mass flowmeter directly measures the fluid mass flow and outputs the mass flow signal, without other equipment, such as temperature tester and pressure gauge, and without conversion.

(2) No movable part

It has no moving parts like rotating shaft, which increases its reliability and requires no mechanical maintenance.

(3) It can accurately measure the small flow. It can also measure the large flow with a large range of temperature and pressure.

(4) Automation of measurement control

The mass flow meter/mass flow controller can output the flow measurement value as standard electrical signal. It is easy to realize digital display of flow, automatic measurement of flow, automatic data recording, computer management, etc. For the mass flow controller, it can also realize automatic flow control. In general,? Analog MFC/MFM input and output signals are 0~+5V or 4~20mA,? The digital MFC/MFM is also equipped with RS232 or RS485 digital serial communication port,? It is very convenient to connect with the computer,? Perform automatic control.

(5) Accurately and quantitatively control the flow

The mass flow controller can accurately control the quantity of gas, which is used for the flow control of many process processes, such as the proportion control of different gases.

(6) High accuracy and repeatability

Accuracy: ± 1% F.S (full scale) Repeatability: ± 0.25% F.S (full scale)

(7) Small size, convenient installation and simple operation

(8) Advanced technology, in line with the trend of development