Selection can be made in five aspects: instrument performance, fluid characteristics, installation conditions, environmental conditions, and economic factors. The various considerations are as follows:

1. In terms of instrument performance: accuracy, repeatability, linearity, range, pressure loss, upper and lower limit flow rates, signal output characteristics, response time, etc;

2. In terms of fluid characteristics: fluid pressure, temperature, density, viscosity, lubricity, chemical properties, wear, corrosion, scaling, dirt, gas compressibility, isentropic index, specific heat capacity, conductivity, sound velocity, mixed phase flow, pulsating flow, etc;

3. Installation conditions: pipeline layout direction, flow direction, upstream and downstream pipeline length, pipeline diameter, maintenance space, pipeline vibration, grounding, power supply, auxiliary equipment (filtration, sewage), explosion-proof, etc;

4. In terms of environmental conditions: temperature, humidity, safety, electromagnetic interference, etc;

5. In terms of economic factors: purchase cost, installation cost, maintenance cost, calibration fee, service life, operating cost (energy consumption), spare parts, etc.