kpaxing
Posts: 4
Joined: Sun Jun 30, 2019 1:25 pm

Moving water from tank to tank controllled by rpi

Sun Jun 30, 2019 2:27 pm

I have a 2000l water tank separated 100m from another 3000l tank. I have a pump to move water from 2000l tank to 3000l tank. This 2000l tank gathers rain water, what i want is that when this tank is full, pump is activated and move 2000l to bigger tank. Then if rain continues and 2000l more are gathered then 1000l should be moved to the other tank and then pump is deactivated. Idea is that if rains continues both 3000 and 2000l tanks are full with minimum use of the pump.

Current design: attach a electrode in 2000l level which flag when tank is full. This input will be read by Rasp, which will activate a relay which activates a contactor which activates the pump. According to pump specs is able to move 2000l in 30 minutes. So, after 30 min Rasp deactivates relay and pump. If 2000l level is again reached, then pump is again activated during 15 minutes which would move another 1000l and then pump is deactivated. No more pump activation will happen till system is manually rearmed when i know that 3000l tank is empty.

Let me know your opinion about this design, any other suggestion would be appreciated.

MadCow42
Posts: 104
Joined: Sun Jul 01, 2012 12:48 am

Re: Moving water from tank to tank controllled by rpi

Wed Jul 03, 2019 8:28 pm

to make intelligent decisions on when to activate the pump and how long to run it for, you really need a level sensor in each tank.

Easy version: a float switch to tell you when each tank is "full"... but if it's not 100% full, you have no idea how much is in there.

Better version: an actual level sensor that tells you the depth of the water in each tank. There are hydrostatic sensors that tell you the pressure, and there are ultrasonic sensors that can measure the distance from some point above the water to the water surface. You'll find examples of both for the Pi fairly commonly.

You really want to know when to turn the pump on, but you also NEED to know when to turn it off - so you don't run it dry and damage it. That's why knowing the water depth is way better.

LTolledo
Posts: 1519
Joined: Sat Mar 17, 2018 7:29 am

Re: Moving water from tank to tank controllled by rpi

Thu Jul 04, 2019 12:46 pm

SAFETY FIRST!
exercise extreme caution, consult a certified electrical technician and have him/her supervise your project.

There are commercially available water level sensors that can interfaced to the RPi to sense water level.

a pair of simple float switches at each tank is probably enough for your requirement.
(one for low level, one for full level)

to run the pump, you need to to have the RPi turn on a relay, then the relay turns the motor contactor (some call this as magnet switch) on/off
better have an overload protection circuit for your motor (this you need to consult a certified electrician, electrical technician, or electrical engineer)
the output of the overload protection circuit is also interfaced to the RPi.

and as you are dealing with water and electric pump-motor, an earth leakage sensor will also be required.....

electrical isolation of the input side and the output side of the RPi are essential... otherwise you'll be replacing your RPi once something goes awry...

I doubt you'll be using some 5v or 12v DC motor-pump for your project, so you'll probably be using 110v or 220/240v AC pump-motor
these are AC mains power.... thus electrical protection circuits are required...
if something really bad happens, and there are no protection circuits, somebody might get fatally electrocuted, electrical fire will burning your place down.... police coming over to investigate.... some litigation to follow... (you know the rest of the story)...

exercise extreme caution, consult a certified electrical technician and have him/her supervise your project.
SAFETY FIRST!
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

kpaxing
Posts: 4
Joined: Sun Jun 30, 2019 1:25 pm

Re: Moving water from tank to tank controllled by rpi

Wed Jul 10, 2019 6:39 pm

Thanks MadCow42 for your suggestions. Really, knowing the water level every moment is something I would like
but if this does not add too much complexity.

I was reading about ultrasonic sensors but seems to be not very precise and there is a problem because tank
could overflow and sensors are not waterproof which is a big limitation in this case. About hydrostatic sensors
I have not read so I will study this possibility, if you have some pointer let me know it.

Last, it there should not be problem to turn the pump off because this pump has integrated a mechanism to automatically
deactivate it when there is not water to pump.

kpaxing
Posts: 4
Joined: Sun Jun 30, 2019 1:25 pm

Re: Moving water from tank to tank controllled by rpi

Wed Jul 10, 2019 6:42 pm

LTolledo, thanks for your answer.

The project is still in a design phase, of course that will consult it with electrical technician before
installing anything.

LTolledo
Posts: 1519
Joined: Sat Mar 17, 2018 7:29 am

Re: Moving water from tank to tank controllled by rpi

Thu Jul 11, 2019 9:34 pm

The simplest float-less level switch from omron (61F-G) is usually my choice for simple level sensing and controlling of pump

another version of the float-less sensor series can sense level on two tanks..
have a peek at omron's float-less level sensor lineup at their site

you can have the output of the sensors as your input to the RPi.
use opto-couplers for better isolation...

[Disclaimer]: Am not affiliated in any way with Omron or any of their distributors or re-sellers.
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

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