mass flow controller

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Thread Starter

paru

We are using a mass flow controller (thermal) in out facility to control the flow of nitrogen gas. I wonder why mass flow controller is used in this application? Is it possible to use other type of control valves?
 
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Asok Kumar Hait

You haven't given sufficient details to answer your question correctly. In which industry you are working and what is the application? I understand you are measuring nitrogen gas flow. There are various instruments to measure nitrogen gas flow e.g. you can use vortex flowmeter, orifice flowmeter and even ultrasonic. All depends on your application requirements and cost. Thermal mass flowmeter is an standard instrument to measure mass flow of gases and air accurately. If you use other types of flowmeters, such as vortex or orifice, they are volumetric flowmeters and you need to have pressure & temperature compensation to derive mass flow from these instruments.

Some thermal mass flow manufacturers also supplies mass flow controller. It is not mandatory to use the mass flow controller given by the manufacturer. If you have a DCS or PLC in your factory you can use the 4-20 ma signal from the thermal mass flowmeter and use standard PID controller to control the mass flow.

Your last comment about control valve is not clear to me. You haven't indicated what type of control valve you are using.
 
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Jan Bradford

> We are using a mass flow controller (thermal) in out facility to control the flow of nitrogen gas. I wonder why mass
> flow controller is used in this application? Is it possible to use other type of control valves?

A thermal mass flow meter offers a number of advantages
• Measure gas mass flow rate directly
• Suitable for applications where temperature and pressures fluctuate
• Highly accurate and repeatable measurements with a typical accuracy of ± 1% FS
• Able to measure accurately low gas flow rates or low gas velocities
• Excellent turn down ratio, typically 50:1
• No moving parts

Other types of flow technology can be used for gas flow but the choice of meter will depend on the medium, measurement requirements and process conditions

Hope this helps

icenta Controls Ltd
specialists in precision flow meters, level sensors, instrumentation & control
www.icenta.co.uk
 
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> We are using a mass flow controller (thermal) in out facility to control the flow of nitrogen gas. I wonder why mass
> flow controller is used in this application? Is it possible to use other type of control valves?

As well as the reasons given another advantage is the Mass flow meters typically have a second output - Density, this is very useful for process control.

We use many Coreolis meters to measure low liquid flows and density (concentration).

The main advantage is great turndown
 
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