Mass flow controller with Labview

[mechatroniclover]

Hello everyone, I have bought a unit 1200 A 2 slm N2 gas MFC. The MAX pressure for this MFC is 500 psi, But there is not any information about MiN pressure.

Is there any MIN pressure requirement for MFCs?

Thank you

[Blokk]

A minimum pressure is usually not specified for obvious reason, since the pressure difference which matters. Think about it, it is basic physics: in order to maintain a flow, you need to have a certain pressure drop. If your upstream pressure (compared to the MFC) is higher than the downstream pressure, you will get a flow. Of course technically you need a certain level of pressure difference. But usually this is fulfilled in most applications (you have a gas bottle upstream for example with a pressure regulator, set to some relatively higher value like 5 bar, and if you have 1 bar downstream it will work...).

You can only face a problem when your downstream pressure is higher than the upstream one: in this case you will NOT get a flow with or without a MFC...

[mechatroniclover]

I got it.
Thank you for the explanation.

[Blokk]

So practically if you have several hundreds of mbar or several bar pressure differences, it should work with any MFC. There are also special MFCs for very low pressure applications (like when you have vacuum downstream, and a few mbar upstream), one example is this one:

http://www.brooksinstrument.com/blog/2012/02/how-low-can-you-go-in-pressure-that-is/

[mechatroniclover]

Nice Information.
Thank you just the same. 🙂

[mechatroniclover]

Hello everyone

This simple schematic that you see, wil be my measurement and control circuit. I have some simple but important questions about it.The first 3 questions:
1- How should I exactly connect or seperate the grounds 1 to 9 in order to have an accurate sensor reading and noise avoiding?
2- what should I do with MFC's case GND, common, and signal common?
3- What about the powers 1 to 7? How many seperate power supplies do I need?
Thank you