(1) Performance of flow meter. It is difficult for any type of instrument to be used in various situations. Therefore, in the specific selection process, the measurement object and purpose must be selected in a targeted manner. Before formally selecting a flow meter, the corresponding designer must select an appropriate measurement method to ensure that no safety accidents will occur due to changes in mechanical strength or failure of the electrical circuit during operation of the measuring instrument. At the same time, the measuring range of the flow meter is determined based on the corresponding process parameters. If the measuring range is too large, it will directly affect the accuracy of the measurement. If the measuring range is too small, an overload condition will occur and the instrument will be damaged. Therefore, the corresponding designer must scientifically select the upper limit of the scale of the flow meter, which is usually about 1.5 times the maximum flow value during the operation of the flow meter.

(2) Characteristics of the fluid being measured. Each fluid has different characteristics in terms of chemical corrosion, fouling, temperature, pressure, sound speed, conductivity, viscosity and density. Therefore, during the instrument selection stage, it is necessary to select an instrument device with high accuracy and good energy saving performance based on the physical parameters of the fluid. For example, when measuring oil slurry, the measuring instrument uses a low Reynolds number viscous flow. A volumetric flow meter or a wedge flow meter can be used, but a standard throttling device cannot be used. Some relatively unique fluids will directly affect the material of the instrument itself. For example, in butadiene devices, the medium BUTA is a relatively easy-to-polymerize substance. Due to certain characteristics of the medium itself, the wetted parts of the detection components installed on the pipeline cannot use copper and copper alloys.

(3) The environmental conditions under which the instrument works. Regarding the working environment of flow meters, it is essentially the environment where measurement is installed, which mainly covers many conditions such as lighting, electrical interference, vibration, safety, atmospheric pressure, humidity, temperature, corrosion, etc. Petrochemical companies must choose appropriate flow meters based on the corresponding installation environment. For example, when installing and measuring in a relatively hot and humid area, try to use a humid and hot flow meter. If a contact flow meter is installed on a long-running pipeline, the corresponding designer must pay special attention to preventing energy loss of the measuring element to ensure the accuracy of the measurement results. There are many flammable and explosive places in chemical equipment, and flow meters are mostly used in relatively dangerous places. Therefore, when selecting flow meters, great attention must be paid to explosion-proof properties to ensure that basic flow measurement work can be completed.

(4) The installation location of the instrument. When specifically selecting a flow meter, it is necessary to examine the specific conditions of the installation site in advance, such as the length, area, and shape of the installation site, and prevent the use of some substandard instrument types, such as differential pressure instruments to achieve the measurement function of straight pipe sections. During installation, ensure sufficient length conditions. In addition, vibration will directly affect many instruments. Therefore, when installing instruments, the vibration should be fixed as much as possible to prevent vibration caused by the impact of the instrument during the material flow stage, which ultimately affects the accuracy of measurement.

(5) Instrument purchase cost. Among the various items purchased by petrochemical enterprises, the purchase of flow instruments is also very critical and must be implemented with the concept of cost saving in mind. Corresponding measurement personnel should consider the specific installation standards of the instrument and select appropriate instruments for some unique types of instrument locations.

(6) Application examples of flow meters. The working conditions parameters of a petrochemical enterprise are: the measured medium is condensate; the viscosity is 0.88 cp; the pipeline is 2"-GC-20103-02; then in the daily operation stage, the normalized flow is 0.516 m3/h, and the maximum flow is 2.5 m3/h; but the work that needs to be undertaken is also between 4 700 and 6 700 kPa; the temperature of the operating environment is between 40 and 66 between C.