Why you need an industrial air flow meter?
As a power source, compressed air has the characteristics of safety and continuity, and it has been widely used in chemical, electric power and other industries. For a compressed air power system, the amount of compressed air usage used is an important index to evaluate the performance of the system and compressed air audits. Due to the high price of existing air flow meters, flow measurement technology has not been widely used directly in many compressed air systems. Gas, as a form of energy (such as natural gas, coal gas, etc.) or a carrier of energy (such as compressed air), is used more and more widely in industry. In particular, major projects such as the West-East Gas Pipeline, HVAC air flow sensor, the development of oil and gas fields, and the urban coal gasification project have attracted unprecedented attention to gas flow measurement.
In order to explore and develop flow measurement technology and instruments that can be accepted by general users, this article takes the general compressed air flow measurement in the industrial production process as the background, and uses thermal air flow meters to measure industrial compressed air to display and corresponding control functions. Various processes in the application of compressed air systems require the realization of the size control of the compressed air flow for audit purpose, which provides a feasible solution for the rational use of gas sources and production cost savings in the industrial production process.
What functions are needed from industrial compressed air flow meter?
The gas flow measurement system for industrial applications, the specific functions include: measure the flow in the compressed air system, uncover inefficiencies and identify leakage of compressed air ,and display the measured instantaneous flow and cumulative flow; control the flow output according to the flow value set according to the process requirements; It can communicate with other intelligent instruments or the host computer, so that the distributed control of the entire gas transmission system can be realized. The industrial air flow meter cost requirement is limited and need to affordable, make the cheap air flow sensor more competitive in the market.
Why Choose Thermal Gas Flow Meters as Industrial Air Flow Meters
There are many
air flow meters types, such as rotameters, vortex flow meters, DP flow meters, ultrasonic air flow meters, here compare those type industrial air flow meters:
Because the pressure loss in the compressed air system will directly affect the conveying effect and reduce the system performance, and DP flowmeter is prone to leakage, blockage and other faults, resulting in a large pressure loss, so it is not suitable for use to measure compressed air flow by differential pressure flow meters;
Turbine flowmeter is based on the action of compressed air after a certain mechanical structure; it causes mechanical movement and rotors to realize compressed air flow measurement. However the mechanical wear is large, the service life is short, and the pressure loss is little large, and the air turbine flow meter cost is not cheap.
The price of ultrasonic air flowmeters is generally very high and not economical solution for air measurement;
Uniform velocity tube flowmeter is mainly for large air pipelines, and the air supply pipeline could be 1inch, 2”, DN50, DN80 or 4 inches industrial compressed air flow sensor;
Positive displacement flow meter sensor is a complex structure and a bulky volume, it is generally used for liquid metering and has a large loss of pressure. It is obviously not suitable for a small compressed air system;
Thermal (or calorimetric) flowmeters have no mechanical moving parts, and the volume is small, electronic air flow sensor has the advantages of small pressure loss a. Although the accuracy can be as high as about 1%, it is enough for this compressed air system, and the pressure has basically no effect on the air flow sensor. The allowable air temperature range is -40-300°C, thermal flow sensors can also detect compressed air leak;
How that industrial compressed air flow meter work and develops?
Thermal mss flow meter to be used as a cheap industrial compressed air flow meter is a type of mass flow instrument based on the principle of thermal dispersion. Although it is a new type of instrument, its measurement principle was proposed early in the 20th century. In the 1980s, heat conduction technology has been used in the measurement of gas mass flow in some developed countries. However, due to the limitation of microelectronics technology, thermal flowmeters had many defects at that time, such as slow response speed and easy interference, all of which were only used in small flow monitoring in some special occasions, or used as flow switches.
After entering the 21st century, with the rapid development of microelectronics and computer technology, the bottleneck that restricted thermal flowmeters in the past no longer exists, and the calculation speed, accuracy and anti-interference ability have been greatly improved, and thermal flowmeter technology has been developed rapidly. At present, it has been widely used in petroleum, chemical, iron and steel metallurgy, electric power, light industry, medicine, environmental protection and other industries.
The thermal flowmeter is based on the principle of thermal diffusion, which requires 2 thermal elements as sensors, and is equipped with corresponding control and calculation circuits, as well as processors and heaters.
First heat a thermal element to a constant temperature higher than the unheated element. With the air flow, the temperature of the heated element will decrease due to the heat dissipation. The feedback circuit is fed back to the processor to increase the current (or voltage) of the heater to keep the temperature difference at a constant value, and then by detecting the changing current (or voltage) to obtain the change in air flow.
Advantages of that type industrial compressed air flow meter
Due to its unique principle and structure, thermal flowmeters used as industrial air flow meters have some perfect features.
(1)
It has a high range ratio, up to 100:1, it can detect large compressed air flow range;
(2)
No need for external temperature and pressure compensation to direct obtain compressed air mass flow measurement under standard condition;
(3)
Compared with the throttling device, there is almost no pressure loss for thermal mass flow meter, reducing the energy consumption.
(4)
Compressed air flow sensor is not easy to dirt or corrosion, and there is no clogging problem, and the plug-in flow sensor is easy to maintain and clean.
(5)
The compressed air flow sensor is very sensitive to changes in the compressed air flow and has high measurement accuracy.
(6)
Industrial air flow meter can be inline air flow meter or insertion air flow sensor
(7)
Insertion air flow sensors can be used for large dial pipe lines , such as 3inch, 4”, 5”,6”,8 inches, DN200, DN600, 1000mm size , 2000mm duct .etc, the price of insertion compressed air flow meter is also very cheap, which is around 900 USD $.
(8)
Electronic industrial air flow transmitter to have LCD display to show compressed air flow rate, total compressed air usage, even air temperature value;
(9)
Industrial air flow meters have 4-20mA,MODBUS, relay and switches output for different prose control purpose, the air flow signal can be transmitted to long distance;
(10)
Industrial air flow meters can display air flow at CFM unit or Nm3/h, compressed air flow meter cfm are widely used;
(11)
Compressed air flow range
Micro compressed air flow meter suitable for small pipeline (1/8”,1/4 inch, 3/8”) flow range: 500ml/min ~166LPM;
1/2” compressed air flow sensor range: 0.03-35 SCFM;
1 inch, DN25 air flow meter: 1.8-175 NM3/H
2 inch compressed air flow meter range: 4.12-413 scfm;
4 inch air flow meter: 16-1648 SCFM;
8” , DN200 dial size flow meter : 31-2777 L/s
10 inches gas sensor, dn250 thermal flow meter for air measurement: 170-17000Nm3/h
DN1000 air flow meter can max measure 164801 SCFM flow rate;
2000mm air flow sensor can detect compressed air flow upto 19444 lps flow;
