Valve that provides pulsed microscale flow.

[engstrum]

Hi all,
I need some help with selecting a valve for a microscale flow application.

I have a pump that provides constant flow at about 50 microL/s. I want to superimpose an AC component on this flow - i.e. some kind of sinusoidal forcing that will provide pulses at about 10 Hz. I also want to be able to control the amplitude (flow rate) of the pulses. I have considered placing a pinch valve downstream from the pump. This may provide the pulsations, but the amplitude is difficult to control.

If anyone has suggestions on how to introduce pulsations and/or how to control the amplitude, please respond.
Any input is greatly appreciated!

Thanks.

 

[aspearin1]

You want peristalsis... why not bypass the valve and use a peristaltic pump to give you what you're looking for, assuming you can get flexible tubing at that small a volume. You could do the same with micro piston pumps. I'm not sure they exist, but in theory they would work. Consider two syringes alternating strokes, filling on the up-stroke and discharging on the down, much like a heart.

As far as the pinch valve goes, that's probably viable. You'll need a solenoid activated pinch valve and a controller to activate the solenoid on and off at your time intervals. At constant flow, though, depending on the time between shut and open, you may build up a micro-back pressure, which will either disrupt your pump, or create an extra surge in flow, which could be good or bad, depending on what you're looking for.

Aaron A. Spearin
ASQ CSSBB
Engineering Six-S'$

http://www.Engineering6ss.com

"The only constant in life is change." -Bruce Lee

 

[MikeHalloran]

Direct the flow through a two- port chamber closed by a diaphragm. Mechanically drive the diaphragm with a sinusoid.



Mike Halloran
Pembroke Pines, FL, USA

 

[JimCasey]

Clippard solenoid valves have small orifices and the kind of frequency response you specified. Might work for you.