Hey all. I have a project where i need to PWM regulate a 12v pump based on a set flow rate. Currently I'm using a diaphragm pump and a small flow rate sensor that reads (according to the seller) 3779 pulses per liter of fluid. I want to keep the flow at a variable rate based of temperature readings. I think i can basically do this like a fan where its speed is monitored based off a tach wire, using the flow sensor as the tach and adjusting the PWM of the motor. I had found several projects like this in the past but now I cant find any of them. Any ideas on this would be great.
I don't see any mention of how you intend to know what the flow rate is.
with the flow rate sensor i mentioned.
Sorry, missed that. Would be better for all if you provided links to the documentation for the various devices.
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I’m trying to find a link for the sensor. I have some images of document buried on my desktop somewhere. The sensor is highly customizable from who ever makes it and I’ve seen multiple values listed for it. I’m highly considering finding a sketch to test the sensor for some info, like total pulses per liter of fluid. The documents I had listed it as 4,21 pulses per liter but it’s a typo and should say 4021. But the seller I got it from says 3779, so it’s kind of a mess of info. It’s a SEN-HZ06C flow sensor.
i think i found the official company site. they have the same typo on the pulses per liter. should be 4021, seller (uxcell) claims 3779 pulses.
https://www.chnsensor.com/2ProductsShow.asp?id=2230&BigClassID=108&SmallClassid=10#topa
Would this type of project be helpful?
Sounds like a perfect application for a PID control...
thats what i was kind of thinking too. just not sure where to even start for that
Hello OutcastZeroOne
Build up the hardware selected and start coding for your project simply.
Have a nice day and enjoy coding in C++.
Дайте миру шанс!
already did that, im trying to expand on the code for better control of my system
this seems like a decently simple guide
Hi, @OutcastZeroOne
This might help with PID control, they use a valve to control flow, but the PID and flow meter example may help.
Tom... 
PS. If you register to this site (free) you will have access to all the magazines project and articles.
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If the pulses per liter is 3780, then pulse rate at 1l/m would be 3780 / 60 = 63 pulses per second (Hz). If you wanted,say, 0.6 l/m, your set point pulse rate would be 63 * 0.6 = 37.8 pulses per second. There are many "tachometer" programs to do that.
"Currently I'm using a diaphragm pump"
You may have to use a long update period to read pulsating flow.
Post a link to the pump.
Pardon me for pointing out that a diaphragm pump always puts out a constant volume per pulse. There is no need for any other flow sensor. Why not just calibrate the pump?
1: I often have to replace the pump due to either the motor burning or the diaphragm membrane itself failing from fatigue.
2: Air can get into the line due to heat from the fluid expanding the air in the reservoir, or a leak forming. While i do have an overflow tank its still possible for it to get low. Due to space constraints I can not put in a larger tank.
3. If there is a leak in the system, the flow rate will drop and I plan to set this to an alarm to audibly notify of the issue but also send a trigger to my 3D printers control board to shut the printer down.
This is only a small part of a much larger system that I've already set up. Currently all i know how to do is set a fixed PWM to my pump. At the moment it slows the pump down if the cold side of the coolant goes over a set temperature to give the coolant more time to be cooled. While this does work, it can not take into account different pumps. And sadly I am not able to always get the same pump so calibrating to a single pump will not work in the long run. Im not sure if I can get this to work the way I want, but I was hoping to make an adaptable system that I could use across several projects.
here is a link for what I've got so far of the system with the more basic pump control.
Hi,
It sounds like you are using the wrong type of pump.
You need an impeller pump that is rotary and not a reciprocal type.
Smoother operation and better load current wise.
Can you please post link to specs/data of your diaphragm pump?
Thanks.. Tom...
impeller pumps fail if ANY air gets in the line. im using the right pump for my application. it dosent matter what my exact pump is, i just need to see if I can control the flow of any pump regulated by the reading of the flow sensor.
all I want is a set up that takes a reading from the flow sensor, adjusts the speed of the pump, waits a few second, takes a reading, adjusts, etc. PID seems the best option for this I just need to figure out how to get it working.
as far as pump styles, Ive used many types in the 4 years ive been water cooling my 3d printer. Quick list of what ive learned over that time.
Impeller pumps: Quiet, many are brushless, low power use. Can NOT self prime, and if any air ever gets into the line they stop working completely. They also are only available with fittings far larger than what my water cooling system uses (4mm). nearly everyone I've seen is for 8mm hose and they struggle with any restriction in the lines.
Gear suction pumps: good pumping ability, can self prime (but only at high speeds), high pressure output. Use a lot of power, very noisy, not good for low speed applications and can struggle with any air in the lines. Most also come with junk motors.
Peristaltic Pump: self priming, high pressure output, good pumping ability, air isnt an issue. Most are low flow, noisy. The one and only I've found with larger hose (3mm ID, 5mm OD) had good rate of flow, but nearly every one would split the hose inside after 6-12h of use.
Diaphragm Pump: self priming, high pressure output, good pumping ability, air isnt an issue. Most come with junk motors, but can be replaced easily with more reliable motors. Diaphragm material can be too soft and fail should any debris be in the system, easily corrected with a filter. Can be very quiet at low speed, but needs to be PWM controlled to protect the motor unless adapted with something like a small brushless motor.
Ever consider a submersible centrifugal pump?