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Topic: Automatic Clamping advice (Read 190 times) previous topic - next topic

Zach_8r3

I have a project where liquid will be pumped through medical tubing (3/16") into a glass or container from another. I'm trying to find a way to pinch off or seal the open end of the tubing (or anywhere on the tubing) the liquid is flowing from automatically after it is done letting liquid flow to prevent contamination back to the original container. I have about six pumps for six tubes, but I need the clamping to work independently from each other. I do not want them to all open and close at the same time. The coding isn't really the issue. I have the main part of the program finished, but this issue is throwing me for a loop.

I've had a few ideas, but none that seem feasible or sensible. I know there is a simple solution out there and I'm over complicating the idea.

Any help or ideas would be much appreciated.

Delta_G

If you use peristaltic pumps then they pinch themselves off. 
If at first you don't succeed, up - home - sudo - enter.

pert

They do sell solenoid pinch valves specifically for that purpose. I've noticed they're quite expensive, probably because of their typical medical or scientific application (other applications will usually just use a standard solenoid valve). You might be able to get a deal on surplus pinch valves if you get lucky on eBay. I think you may be limited to certain properties of tubing.

Possibly more fun/cheap would be to find a DIY solution. Solenoids are fairly cheap, you just need to get one with enough force and build the pinch parts. Even if you don't need a pump, the mechanisms you find in DIY peristaltic pumps could be adapted to work as a pinch valve if for some reason you found using a motor preferable to a solenoid.

dave-in-nj

depending on the tubing, some is exceedinglly soft and can pinch easily.
some is just short of steel tubiing and will not pinch off.

I  have used a stepper with a roller, much like a peristaltic pump, but just one roller that is off center.  used it to drip feed lubricant on a cutting tool.

if your requirement is that no two can EVER work at the same time, you can have one drum with cams and each tubing goes under one cam.  only one cam would allow flow.  you could make with wood drum very easily and with a cover, it would look good.

ardly

Use Hoffman Screw Claps driven by motors?
"Facts do not cease to exist because they are ignored" - Aldous Huxley

dougp


Zach_8r3

Forgot to mention I'm trying to avoid peristaltic pumps do to slowness. And I don't want to have to buy a whole bunch of them to compensate.

pert

Solenoid driven ball valve?
That picture is quite strange:

Maybe they mixed up their product photos?

Are you suggesting using the ball valve to pinch the tubing off, that's an interesting idea! Or are you merely suggesting that it should be used for its intended purpose? In that case I would consider a standard solenoid valve instead, which should be cheaper than a ball valve. They do require constant power to stay open but that most likely isn't a problem for this application and can actually be beneficial to give a default cutoff in the event of loss of power.

Usually when people are using the pinch valve it's because they can't expose the fluid to the materials of a valve. This could be to avoid contamination or to make it easier to completely clean the system.

dougp

That picture is quite strange:
Yes, it's reminiscent of what's in your toilet tank.

Are you suggesting using the ball valve to pinch the tubing off, that's an interesting idea! Or are you merely suggesting that it should be used for its intended purpose?
The latter.  Just the first thing that popped into my head.  Actually, if only noncorrosives are used, one like that for your refrigerator icemaker would do the job too.

silverminer

Are you able to pump up and over (down) into the vessel while supplying a vacuum break at the top so when the pump shuts off the liquid flows back both ways? No mechanical devices required.

TKall

Why not just use a check valve?

TKall

https://www.amazon.com/dp/B0094FYL02/ref=asc_df_B0094FYL025266962/?tag=hyprod-20&creative=395009&creativeASIN=B0094FYL02&linkCode=df0&hvadid=167154348866&hvpos=1o1&hvnetw=g&hvrand=3144053916589537286&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9021324&hvtargid=pla-307225008900


dave-in-nj

Forgot to mention I'm trying to avoid peristaltic pumps do to slowness. And I don't want to have to buy a whole bunch of them to compensate.
3/16" dia tubing will be slow unless you spend some money on powerful pumps.
as for backlow, just keep the discharge above the top of the target vessel, zero possibility of backflow

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