Ⅱ. Working principle
Temperature pressure compensation vortex flowmeterThe flow profile is similar to that of a Venturi tube (Figure 1), with a set of spiral guide vanes placed on the inlet side. When the fluid enters the flow sensor, the guide vanes force the fluid to generate intense vortex flow. When the fluid enters the diffusion section, the vortex flow is subject to backflow and begins to rotate twice, forming a gyroscopic vortex precession phenomenon. The precession frequency is proportional to the flow rate and is not affected by the physical properties and density of the fluid. The detection element can measure the secondary rotation precession frequency of the fluid to obtain good linearity over a wide range of flow rates. The signal path is amplified, filtered, and shaped by a preamplifier into a pulse signal proportional to the flow rate, which is then sent to the microprocessor together with temperature, pressure, and other detection signals for further processing. Accumulation processing, And display the measurement results (instantaneous flow rate, cumulative flow rate, temperature, pressure data) on the LCD screen

Ⅲ. Flow meter structure
Temperature pressure compensation vortex flowmeterComposed of the following seven basic components: (Figure 2)

1. Vortex generator
Made of aluminum alloy, spiral blades with a certain angle are fixed at the front of the shell contraction section, forcing the fluid to generate strong vortex flow.
2. Shell
It is equipped with flanges and fluid channels of a certain shape. Depending on the working pressure, the shell material can be cast aluminum alloy or stainless steel. 3. The intelligent flow integrator consists of a temperature and pressure detection analog channel, a flow detection digital channel, a microprocessor unit, a liquid crystal drive circuit, and other auxiliary circuits, and is equipped with an external output signal interface. The flow integrator consists of a temperature and pressure detection analog channel, a flow sensing channel, and a microprocessor unit, and is equipped with an external output signal interface to output various signals. The microprocessor in the flowmeter compensates for temperature and pressure according to the gas equation and automatically corrects the compression factor. The gas equation is as follows:

In the formula:
Volume flow rate under QN standard conditions (m)³/h )
Volume flow rate under QV operating conditions (m)³/h )
Temperature of the fluid being tested (K)
The gauge pressure measured by the pressure tapping hole of the P flowmeter (KPa)
Atmospheric pressure under PN standard state (101.325KPa)
Temperature under TN standard condition (293.15K)
Pa when t atmospheric pressure (KPa)
Compression coefficient of Z gas under working conditions
Compression coefficient of ZN gas under standard conditions
Note: When calibrating with a bell jar or negative pressure, take ZNZ-1 and calculate the over compression factor for natural gas (ZN/Z) 1/2-FZ according to the standard SY/T6143-1996 of China National Petroleum Corporation.
4. Temperature sensor
Using Pt100 platinum resistor as a temperature sensitive element, its resistance value corresponds to temperature within a certain temperature range.
5. Pressure sensor
The piezoresistive diffusion silicon bridge is used as the sensitive element, and its bridge arm resistance will undergo expected changes under external pressure. Therefore, under a certain excitation current, the potential difference between its two output terminals is proportional to the external pressure.
6. Piezoelectric sensor
Installed near the throat of the expanding shell, it can detect the frequency signal of vortex precession.
7. Racomer
Fixed at the outlet section of the shell, its function is to eliminate vortex flow and reduce the impact on downstream instrument performance.
Ⅳ. Flow meter selection

In the selection process, two principles should be grasped; Namely: firstly, to ensure production safety, and secondly, to ensure usage accuracy. To achieve this, three selection parameters must be implemented, namely the commonly used flow rate in the near and long term (mainly used to select the nominal diameter of the instrument), the design pressure of the measured medium (mainly used to select the nominal pressure rating of the instrument), and the actual working pressure (mainly used to select the pressure rating of the instrument pressure sensor).
a. When the measured flow rate is known to be the operating volume flow rate, the appropriate nominal diameter can be directly selected according to the flow range in the table;
b. When the measured flow rate is known to be the volumetric flow rate under standard conditions, the volumetric flow rate QN of the standard flow rate should be converted to the volumetric flow rate Qv of the operating condition first, and then the corresponding nominal diameter should be selected according to the flow range in the technical parameter table;
c. When both types of flow meters can cover the volumetric flow range, the smaller diameter should be selected as much as possible under the allowable pressure conversion;
d. Do not make the actual small flow rate Qmin lower than the lower limit of the flow rate of the selected nominal diameter flowmeter;
e. When there are special requirements for flow range and nominal pressure, an agreement can be made for ordering
f. The selection calculation formula is as follows:

In the formula, T and P.Pa have the same meanings as above, Q is the volumetric flow rate, Qn is the standard volumetric flow rate, and Z/Zn values are listed in Table 2. Due to the large calculation step size, the data in the table is for reference only. The data in the table is calculated based on the true relative density of natural gas Gr-0.600, and the mole fractions of ammonia and carbon dioxide are both 0.00. When the medium pressure is below 0.1MPa, it can be estimated as Z/Zn=1.
Ⅴ. Outline dimensions and installation dimensions diagram of flowmeter
Temperature pressure compensation vortex flowmeterThe external dimensions of the flowmeter are shown in Figure 3, and the dimensions not indicated in the figure are listed in Table 1. The flowmeter adopts a flange connection method, and the flange dimensions comply with the GB/T9112~9113-2000 standard.

Selection and Installation

In the selection process, two principles should be grasped; Namely: firstly, to ensure production safety, and secondly, to ensure usage accuracy. To achieve this, three selection parameters must be implemented, namely the short-term, long-term, and commonly used flow rates (mainly used to select the nominal diameter of the instrument), the design pressure of the measured medium (mainly used to select the nominal pressure rating of the instrument), and the actual working pressure (mainly used to select the pressure rating of the instrument pressure sensor).

a. When the measured flow rate is known to be the operating volume flow rate, the appropriate nominal diameter can be directly selected according to the flow range in the table;

b. When the measured flow rate is known to be the volumetric flow rate under standard conditions, the standard condition volumetric flow rate Q should be calculated first_NConvert to the operating condition volume flow rate Qv, and then select the corresponding nominal diameter according to the flow range in the technical parameter table;

c.When both types of flow meters can cover low and high volume flow rates, the smaller diameter should be selected as much as possible under allowable pressure loss;

d. Do not make the actual small flow rate Qmin lower than the lower limit of the flow rate of the selected nominal diameter flowmeter;

e. When there are special requirements for flow range and nominal pressure, an agreement can be made for ordering.