Mass flow controller question

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brett_kvo
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Re: Mass flow controller question

Post by brett_kvo » Thu Feb 18, 2021 1:01 am

Thanks for the advice all.

RIchard--any idea how you might digitally control one of those leak valves? I appreciate the precision and repeatability of it, but we're attempting full computer controls and the MFC checks the box.

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Richard Hull
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Re: Mass flow controller question

Post by Richard Hull » Thu Feb 18, 2021 6:34 am

Easy if you have the skills. Remove the knob and attach a high torque stepper motor. Count steps from off to various calibrated running gas points and interpolate between step counts to create an array that can step to numeric gas pressure to needed step counts. Or simply avoid this and have a forward and reverse rocker switch to drive the motor in or out. Finally and most desirable is that the motor stepper could be linked to the pressure gauge in software to cause it to seek a punched in pressure and hold it there in a virtual servo loop. Many ways to skin this cat once a stepper is attached.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

brett_kvo
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Re: Mass flow controller question

Post by brett_kvo » Fri Feb 19, 2021 12:14 am

Great. Thank you. That's what I had in mind as well. I like this direction over the MFC. :)

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Bob Reite
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Re: Mass flow controller question

Post by Bob Reite » Fri Feb 19, 2021 3:09 pm

I use a 0-10 SCCM mass flow controller. I set the flow rate with a 10 turn pot. For my chamber, I usually operate between 3-5 SCCM.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.

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Artem Artemov
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Re: Mass flow controller question

Post by Artem Artemov » Fri Feb 19, 2021 8:36 pm

I had an idea to connect a stepper motor to my needle valve, but this is archaic. You need an motor, a driver, a controller, calibration, and dance with drum. I think it's easier to use mfc with an analog control signal. But if you are serious guys, you can use mfs and vacuum gauge with devicenet, combining everything into one network. Many phillips vacuum gauges have a devicenet. Then you will need to buy an mfc with this function for perspective. You can fully automate everything.

In the future, I want to connect everything through this network. I bought vacuum gauge with devicenet, but they can be used without using this network, the gauge have screens. But such gauge with a screen are expensive(


Ps You can also use the MFC and needle valve at the same time. You give the signal to fully open the mfc and work manually with the valve wheel.
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Liam David
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Re: Mass flow controller question

Post by Liam David » Fri Feb 19, 2021 9:28 pm

The Devicenet connector pinouts include can_h and can_l. If I'm not mistaken, you might be able to communicate with the gauge using the standard CAN bus. There are Arduino shields/breakouts that would make this pretty easy. I have a convectron gauge identical to Artem's, but haven't investigated whether this is possible and am not familiar with the standards, so take it as is.

brett_kvo
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Re: Mass flow controller question

Post by brett_kvo » Fri Feb 19, 2021 11:28 pm

Hey Bob, could you tell me the exact make/model of your MFC? Just curious what's worked well for you.

We managed to find an old precision leak valve laying around, so I think we may go that route for version 1.0 (manual control) of our reactor. I think we'll pursue either an MFC or a stepper-motor driven leak valve moving forward.

Thank you all for your thoughtful responses. This information just can't be readily found anywhere else on the internet.

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Richard Hull
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Re: Mass flow controller question

Post by Richard Hull » Sat Feb 20, 2021 6:20 am

You are right Brett. We have years of accumulated knowledge here and lots of folks who have done the same thing in many different ways, successfully. You came to the right place. Thanks for the accolades to all of us and this site.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Bob Reite
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Re: Mass flow controller question

Post by Bob Reite » Mon Feb 22, 2021 9:49 pm

Mine is a Sierra Instrumentation "Side track III" "cust code I-458 Range 0-10 SCCM Orifice .010" Gas H2. I found it on Ebay. Any MFC that can be set for 0-10 SCCM will do.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.

brett_kvo
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Re: Mass flow controller question

Post by brett_kvo » Mon Feb 22, 2021 10:17 pm

Thanks Bob! Much appreciated. :)

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