Selection of hydrogen flow meters and flow rate issues
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We are currently selecting a hydrogen flow meter. The typical operating conditions are a hydrogen pressure of 10 bar, a flow rate of 400 Nm3/h to 1100 Nm3/h, and a maximum temperature of 40°C. We are considering either an vortex flow meter or a mass flow meter; one manufacturer has suggested a vortex flow meter with a diameter of DN40, while the mass flow meter should have a diameter of DN25. According to the design specifications for hydrogen stations, the maximum flow velocity of hydrogen is 25 m/s. The flow rates of DN40 and DN25 flow meters both exceed this value at 1100 Nm3/h; in addition, vortex flow meters require straight sections, and the flow velocity in those straight sections also exceeds 25 m/s. The manufacturer says that the flow meter and its straight pipe section constitute a local area, so it doesn’t matter if the flow velocity is too high. I would like to ask everyone if you have encountered similar problems or how you solved them? Thank you!
When selecting a hydrogen flow meter, it is necessary to consider the relationship between the meter’s diameter and the flow rate. Although the manufacturer states that the flow meter and straight pipe sections are areas where the maximum flow velocity can be exceeded, it is still best to follow the design specifications to ensure the safe operation of the system. You can consider the following points: 1. Re-evaluate the diameter of the flow meter to see if there is a more suitable specification that can meet the requirement of a hydrogen flow rate not exceeding 25 m/s. 2. If it is truly impossible to find a suitable diameter, it is possible to discuss with the design team whether the maximum flow rate specified in the standards can be adjusted, or whether there are other safety measures that can handle situations of excessive flow rates. 3. Consider using a flow control valve or other flow regulation devices to reduce the flow rate entering the flow meter section. It is recommended to work closely with professional manufacturers and design firms to ensure that the selection of hydrogen flow meters meets both the project requirements and system safety standards. .
In my opinion, it’s better to choose a mass flow meter – there are no requirements regarding straight pipe sections, and the requirement of a pipeline flow velocity of 25 m/s is avoided. Many of the instrumentation devices inside the system, such as control valves and flow meters, are smaller in diameter than the pipe itself, so it’s necessary to reduce the pipe diameter； The flow velocity inside it is higher than that in the pipeline, in order to facilitate control or measurement.
The mass flow meter is much more expensive; the pressure drop also seems to be higher
This post was last edited by Zhong Jingwei on 2025-6-27 at 18:55. We use a Coriolis mass flow meter for hydrogen; the flow velocity inside the meter reaches around 120 M/S, and we have been worried about this issue
There are no specific flow rate requirements for the instrument; it is recommended to visit the site of the user who operates the flow meter manufacturer’s product.