The flow meter consists of 5 parts

　　1. Flow sensor

　　2. Pressure sensor

　　3. Temperature sensor

　　4. Gas waist wheel flowmeter (mechanical)

　　 5. Intelligent flow totalizer

　　 The working principle of the smart gas waist wheel flowmeter (see Figure 2) a

　　Intelligent gas waist wheel flowmeter is mainly composed of shell, conjugate rotor and intelligent flow totalizer. A pair of conjugate rotors installed in the measuring chamber are under the action of the pressure difference between the inlet and outlet of the circulating gas (Pin>Pout), and the rotors are kept in the correct relative position through precision-machined adjustment gears. The working gaps are maintained between the rotors, between the rotor and the shell, and between the rotor and the wall plate, realizing continuous non-contact sealing. Every time the rotor rotates, it outputs four times the effective volume of the metering chamber. The number of rotations of the rotor is transmitted to the intelligent flow totalizer through the magnetic seal coupling and deceleration mechanism, thereby displaying the cumulative volume of the output gas. The measurement process and working principle are shown in Figure 1 (only a quarter cycle is shown in the figure).

       Position 1            Position 2             Position 3                Position 4

Figure 2 Working principle of gas waist wheel flowmeter

　　 The working principle of the intelligent flow totalizer (see Figure 3)

　　The intelligent flow totalizer is composed of temperature and pressure detection analog channels, flow sensor channels and microprocessor units, and is equipped with an external signal interface to output various signals. The microprocessor in the intelligent flow totalizer performs temperature and pressure compensation according to the gas equation, and performs compression factor correction. The gas equation is as follows:

(1)

Where:

　　Qn: Volume flow rate under standard conditions (m3/h);

　　Qg: Volume flow rate under working conditions (m3/h);

　　Pg: Gauge pressure at the pressure detection point of the flowmeter (kPa);

　　Pa: local atmospheric pressure (kPa);

　　Tg: the absolute temperature of the medium (273.15 + t) (K);

　　T: The temperature of the measured medium (℃);

　　Zn: the compressibility coefficient under the standard state;

　　Zg: Compression coefficient under working condition;

　　Tn: the absolute temperature in the standard state (273.15 + 20) (K);

　　Pn: standard atmospheric pressure (101.325 kPa);

　　P: P= Pa+ Pg.

　　Note: For natural gas Zn/Zg=Fz2, Fz is called the super compressibility factor. This product is calculated according to the formula in China National Petroleum Corporation's standard SY/T6143-1996.

1. Using advanced microcomputer technology and high-performance integrated chip, the whole machine has powerful functions and superior performance.

    2. The circuit adopts surface mounting technology, compact structure, strong anti-interference ability and high reliability.

    3. Integrating high-precision temperature, pressure, flow sensors and intelligent volume corrections, it can detect the temperature, pressure and flow of the measured gas, and perform automatic flow tracking compensation and compression factor correction calculations.

    4. Pressure sensors, temperature sensors, and flow sensors are all built-in, making the structure more compact.

    5. Adopting advanced micro-power consumption high-tech, the whole machine has low power consumption. It can run on long-term power supply with the built-in battery, and it can also be powered by an external power supply.

    6. According to the flow frequency signal, the meter coefficient can be divided into six segments to automatically perform linear correction, thereby improving the accuracy of the meter.

    7. It has fault self-diagnosis and alarm functions, high reliability, LCD display, clear and intuitive, and convenient reading.

    8. The flowmeter has a pulse signal output, and can also output 4-20mA standard analog signals according to user needs.

    9. The meter comes with a real-time database, which can form a telephone meter reading network through the RS-485 communication interface and the factory's special MODEM, which is convenient for centralized data collection and real-time management.

    10. Adopting advanced micro-power consumption technology, the whole machine has low power consumption and can run for more than five years with built-in battery.

    11. The flow value is displayed on the spot, and it has a variety of signal output functions to meet the needs of different sites and systems.

    12. Use E2PROM data storage chip to save user parameters, manufacturer parameters and certain historical records.

    13. A high-contrast three-line LCD display can display the date, standard cumulative flow, standard instantaneous flow, medium temperature, pressure value and battery voltage.

    14. With real-time data storage function, it can prevent data loss when the battery is replaced or sudden power failure. In the state of power failure, the internal parameters can be stored for a long time.