Proportional valve and PWM

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Thread Starter

Alfred Tang

I am looking for a proportional control valve to control the output flowrate of an equipment. The pressure would be at 50-60psig, flow rate ranging from 10-30LPM and it is for oxygen.

Also we wish to control this by the PWM signal, that is generated from our SMC pneualpha2, rather than using an analog signal.

Any advice of the hardware? and price range?

Thanks.

Alfred Tang
 
I am confused. I think of Pulse Width Modulation outputs as on/off circuits where the period is set as a constant and the duty cycle or on-duration is the result of a PID calculation. Such circuits cannot be used for continuous modulation applications such as control of a variable like as flow rate. It can be used to control dosage over time, say 1000L O2 addition to a biological reactor over the course of an hour. If this is the case, any two position valve with a Cv appropriate to the maximum rate you can tolerate will suffice. If this is a biological application, you might consider a diaphragm valve with a travel limiter.
 
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alexeypichardo

Dear Alfred:

At this time, we are working on a very similar project, a FPV Flow Proportional Control based on a PWM over a Burkert Valve or similar.

The PWM control is good because need a very few electronic components, but we have certain noise on the flow output.

Also, we are considering an analog control which more reliable but a little bit lower in time response.

It depends on your general requirements.

Let me know your e-mail address and we may share some information

Best regards,


Alexei
 
If you will use PWM higher frequency (10 kHz or more) that will make as equivalent to analog control. One of the place I am using arround 50 kHz and it controls like a servo valve.
 
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