I have multiple peristaltic pumps for my dosing system I am setting up. Have been using the Atlas pH, EC & Temp Circuits with the probes (not cheap).
I have multiple 12v peristaltic pumps which I have the choice of using motor driver or simply relays (I have 8 channels of either and controlling the flow using the drivers might be better?) but I would also like to make use of the Atlas flower meter totalizer that I have so I can more accurately see how much each pump has dispensed. I feel that would be better than time based pumps either relay or driver.
What would you recommend? The flow meter can work down to 1 L/min (0.2GPM) up to 15 L/min (3.96 GPM) which is perfect for me: 3/8″ Flow Meter Kit | Atlas Scientific
My plan was to have all the dosing pumps pipes run through the one flow meter and set to turn off after X amount is dispensed with a failsafe on the timing of the pump.
Im currently 3D printing out the cases which I’m going to be DIN mounting and ideally would like to run everything off a single ESP32 in ESPHome and not reliant on Home Assistant controlling it.
Any tips or points would be greatly appreciated. .
I have no experience with pump like these so sorry If I make a mess on this.
My only hint is that in this way you’ll need to be sure that once a pump is in action the liquid did goes out from the intended path and can’t be pumped back to the other circuits. This could be solved by one way valves, if needed.
The other drawback is that if 2 pumps are on at the same time the measured flow will be the sum of both circuits.
I understand your concern, would using steppers be better than monitoring just the flow rate?
Would a one way valve be needed? I mean once the pump comes to a stop, my understanding is that as long as that the incoming pipe is still submersed in the nutrient etc then the pressure (or what the correct terminology is) would stop the flow immediately instead of emptying whats left in the tube? Or am I completely wrong?
I would make sure that only 1 pump is dispensing at a time. To be honest it wants to be that way anyhow and speed is not a priority.
Thanks again and also, what about help with regards too coding this, is this something you are comfortable with?
The nature of peristaltic pump prevents quite well back feed, I don’t think you need one way valves.
But what about “contamination” of different liquids passing through same flow sensor?
Obviously time based dosing is simplest and cheapest option while stepper / flow meter approach gives more control / feedback. Only you know how accurate it has to be…
You didn’t post any details of your pumps, so difficult to suggest best driving method. If you go with DC motor driver, you get speed control option, needed or not, and driver usually have some snubber circuit onboard, with relays you have to add at least flyback diodes. I recommend Pololu drivers, good quality and inexpensive.
Good to know that the return flow is not a problem.
Remembering the fact that I know nothing on these pumps, determining the flow only analyzing the use of the pump motor (driver/stepper) could lead to some false reading: if there’s an air bubble or the fluid tank is empty the motor turn for 30 seconds or for whatever revolutions but no fluid will reach whatever is down flow of the pump.
Don’t know it this could be a problem
Of course it would be.
But it would be problem to the flow sensor as well. If you read documentation for flow sensor you see you can have contaminants (need filter), air bubbles, and you also have to design it a way there’s no turbulence.
Only weight sensor or optical / camera approach can give “100%” accurate dosing.
But depending on accuracy needed and all factors on your setup and ambient factors, time based dosing can give good results. And you can always add flow sensor if contamination is not a problem.
I personally wouldn’t pick stepper as a method of control.
You didn’t even tell what accuracy you are looking for.
If your liquid consistency, temperature and motor voltage are all constant, I expect good results just time based.
If your liquid is dirty, full of bubbles and you don’t take care of turbulences on your design, I don’t expect good accuracy even with that sensor.
