Hello!
I'm planning to create a system with one pump, which moves the water from a bowl to another and viceversa.
So far, I had no problem finding a pump that can move the water in one direction.
But my problem is to do the same in the opposite direction, with the same pump.
Do you know any particular pump that I can use? Do you think I can use "any" pump and invert the flow just with the code?
Thank you
Gabriele
If it's a DC pump it may pump in the other direction with the DC polarity reversed. (I guess that depends on the insides of the pump; maybe even if the motor runs backwards, it might not pump?
BUT assuming it does work with the polarity reversed you can likely do that with code, provided you're connecting the motor via an h-bridge. If you currently have it connected via a simple transistor setup, that won't cater for reversal.
Please don't say you have the pump motor directly connected to 2 digital pins as its voltage supply. Hopefully you have a transistor or h-bridge in place, and the Arduino merely controls the electronics, and isn't trying to be a power supply.
Google for "peristaltic pump". Those work in both directions.
The problem is that I have to move 750mL of liquid in less than 20 sec, so I can't use a peristaltic pump, because it's too slow.
The DC pump is what I was thinking, but I wasn't sure I could do via software.
What about moving a piston of a syringe?
Do you think I can achieve a good speed with a standard stepper motor? I saw this video https://www.youtube.com/watch?v=UHa-OKb_CiM but the speed is too slow for me.
I was thinking to use a 500mL syringe and the same setup to move the piston.
Quickest way to test the pump you have, is to reverse the supply directly over your pump - without any circuitry - just the pump and the battery.
If it works, you know your pump should work.
And you did not think that was an important detail of your question?
Get two pumps - one for each bowl and switch them on as required.
Forgive the crudity of the drawing but you can use any cheap fast pump if you use 4 solenoid actuated valves.
Reminds me of an h-bridge. Guess this is a ph-bridge.
Much cheaper to get two pumps!
Like an h-bridge but with water 
You're absolutely right, but it all comes down to the project requirements and both are valid methods.
Can more than one pump be used?
Does it have to be a reversible pump?
These are question OP can help us understand.
Edit: The valve setup can also use a couple y-connectors to reduce the connection to a single tube to each bowl and if that tube is at the bottom of the bowl then it can have a very impressive filling and draining effect while completely hiding the tubes.
Perhaps you gave up your search too soon. I quickly found Peristaltic pumps That gave 100 l/hour to 44,000 l/hour .
Were you looking at single lobe pumps or multiple lobe pumps?
What is you budget?
Paul
Thank you a lot for all the suggestion!
I try to explain better my project:
I have 3 bottles with 3 different liquids, and one single empty bottle.
I would like to set a timer where at the end it pumps the first liquid in the empty bottle, then after a couple of seconds, put the liquid back. This for all the 3 liquids, one after the other.
I firstly thought about a peristaltic pump (the ones on Amazon, so I think they are pretty basic), but I didn't know if it was possible to reverse the flow.
Then I thought about a syringe, with a stepper motor that can pull and push the piston, but I think it's not a good way because there is too much liquid to pump (~750mL).
What is your plan to keep the liquids from mixing inside the pump? There will always be some remaining liquid. Also, doe you require a self-priming pump, or will the source liquid always be above the pump intake?
Paul
@Paul_KD7HB I am planning to put 3 pumps per bottle. My first plan was to use the peristaltic pump, so I thought to keep some of the liquid in the tube, since the process has not to be precise: I just want all the liquid to move, and in the end I will lose the "X" mL which remain in the tube, but it's not important. Thinking about a different kind of pump, I actually have no idea unfortunately.
Please draw a picture.
As you can see from mine quality does not matter so long as you effectively communicate your idea. Pretty much anything readable is good.
No matter what you decide, your project is to use a pump to create a vacuum so the air pressure will force the liquid up into the pump. Your decision on pump needs to take that into consideration.
Paul
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