Flow meter is a kind of instrument used to measure fluid flow, widely used in industrial production, energy measurement and other fields. The correct selection of flowmeter is to ensure that the flowmeter to give full play to the best measurement performance of the main links. A flowmeter performance and then good, reliable quality, if the selection is not correct, but also can not play the best measurement performance of the flowmeter, it will waste time and a lot of cost. Therefore, the correct selection of the flow meter is essential.
Gas flowmeter selection needs to provide the following main technical parameters :

1. The measured medium: first of all, to understand the nature of the measured medium, including media composition, density, viscosity, corrosivity, etc.. Different flow meters can measure different media. For example, vortex flowmeter, rotary vortex flowmeter can measure hydrogen, oxygen, and gas turbine flowmeter can not be measured.
2. Flow range: determine the flow range of the measurement medium, that is, the minimum flow and maximum flow. According to the actual flow range, select the appropriate nominal diameter of the flowmeter to ensure measurement accuracy. Flow rate is divided into working condition flow rate and standard flow rate, when the customer is given the standard flow rate, according to the gas equation formula will be the standard flow rate converted to working condition flow rate, and then check the flow range of each flowmeter table, select the appropriate nominal diameter of the flowmeter.
3. working pressure and working temperature: used to determine whether it is within the design parameters of the flowmeter. Different flowmeter design pressure and design temperature is not the same. Standard flow rate conversion of the working condition flow rate, the need for pressure and temperature values involved in the calculation.
4. Precision requirements: According to the user’s accuracy requirements, to determine whether the flowmeter to meet its requirements. Gas flowmeter accuracy level is generally 1.0 and 1.5 levels.
5. Nominal diameter of the pipeline: to determine the nominal diameter of the selected flowmeter and the nominal diameter of the pipeline is matched, whether the pipeline needs to change the diameter.
6. Output signal and communication mode: If you need to transmit the flowmeter measurement data to the control system, you need to consider whether the flowmeter has the required communication interface and data transmission function. Gas flowmeter output methods include pulse signal output, 4-20mA current signal output, HART protocol, RS485 communication.
7. Explosion-proof and protection requirements: According to customer requirements, some occasions require explosion-proof and protection requirements, to consider whether the selected flowmeter to meet the relevant requirements.
8. Environmental conditions: consider the flow meter will be installed in what environment, including ambient temperature, humidity, pipeline vibration, safety and electrical interference and other conditions. Ensure that the selected flowmeter can adapt to these environmental conditions.
   Gas flowmeter selection is a complex and important process, need to consider the above main technical parameters, comparison and analysis, choose a suitable gas flowmeter. At present, our gas flowmeter has: vortex flowmeter, vortex flowmeter, gas turbine flowmeter and gas girdle wheel flowmeter, which can be chosen by users.