What flow meter is used to measure nitrogen?

A flow meter is an instrument that measures flow. It can measure the flow of various gases and liquids. For nitrogen, the following flow meters can be used:

1. Ultrasonic flow meter: Ultrasonic flow meter uses the propagation speed and time difference of sound waves in the flowing medium to measure the flow rate. Because ultrasonic waves do not react with gases, an ultrasonic flow meter can be used to measure the flow of nitrogen.

2. Vortex flowmeter: Vortex flowmeter uses the vortex effect of the fluid to measure flow. Vortex flow meters are suitable for flow measurement of various gases and liquids, including nitrogen. 

3. Thermal mass flowmeter: Thermal mass flowmeter uses the principle of heat conduction to measure flow. Because thermal mass flow meters do not react with gases, thermal mass flow meters can also be used to measure the flow of nitrogen.

In summary, the above flow meters can be used to measure the flow of nitrogen. The specific choice of flow meter needs to be decided based on the actual application scenario and usage requirements.