Micro metered pump

Hi People,

I am new to this forum and to be honest don't know much about electronics. Looking for some pointers on what controllers, circuit boards and controllers I would need for my project.
I would like to see if this is achievable for a machine I would like to build. Am pretty sure it is possible. I need a 6 or 12v micro pump to measure out a chemical ranging from 5-50mls with maybe max 5% error. At the moment I don't have a use for more than 50mls but who knows what the future may hold.
Not sure if I require a geared or diaphragm pump. Basically every time the button is pressed, upto 20-40 times per min I need a delivery of the chemical. I understand some chemicals will corrode the plastic etc of the pump. Enough pressure is required to deliver the chemical in a short solid squirt through 2-4 nozzles.
I have a battery operated garden sprayer so that would be an ideal vessel to hold the chemical but the pressure and volume is too high. So a smaller capacity pump would be ideal.
Any advise and pointers I would really appreciate or direction to find the pieces I am missing, have contacted a couple of vendors on alibaba but having a hard time explaining what I need. Dont want to reinvent the wheel.

TIA, Greg

Welcome to ETO!
A peristaltic pump might suit your needs, since the chemical would then pass through a flexible tube and not contact any other part of the pump mechanism.

Thanks, we used to use a similar design on an old agricultural sprayer pump that attached to the tractors PTO.
That has given me an another idea! What about a facet fuel pump? Will it be possible to program a controller to only push 1 or partial stroke on demand and have operator push a button to cycle the pump? I can always machine something to fit inside the pump as I have done in the past on hydraulic cylinders to reduce the stroke, to calibrate the pump or have a controller to fire it for fraction of seconds till it produces the required qty of liquid. haven't opened a facet pump yet.

zimbo said:

What about a facet fuel pump?

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I'm not familiar with those and don't know their operating principle. A quick google indicates there are several versions under that brand name.

I maintain cooling equipment which is dosed with treatment.
The dosing pumps are solenoid type, the stroke of the solenoid can be adjusted to alter the dose.
The pump heads are available in different plastics for different chem's.
They are kinda expensove, but are the right thing for the job.

I'd cobble together a "syringe pump" if you have access to polyethylene spring bodies. You can purchase candles for transfer through septa or get double-ended Luer-lock Teflon tubes that fit the syringes and get direct transfer.

I ran into this: https://www.syringepump.com/NE-1000.php

KeepItSimpleStupid said:

I ran into this: https://www.syringepump.com/NE-1000.php

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Wow, $775. I should market my design. My total cost was under $75 for parts and the pcb is designed & code is already written.

zimbo said:

I need a 6 or 12v micro pump to measure out a chemical ranging from 5-50mls with maybe max 5% error. At the moment I don't have a use for more than 50mls but who knows what the future may hold.
Not sure if I require a geared or diaphragm pump. Basically every time the button is pressed, upto 20-40 times per min I need a delivery of the chemical. I understand some chemicals will corrode the plastic etc of the pump. Enough pressure is required to deliver the chemical in a short solid squirt through 2-4 nozzles.

Click to expand...

You have some specific needs.

I don't know, but I do have experience with syringe pumps and I don't think a syringe pump will do what you want. Many of these are scientific instruments that are designed to produce accurate disbursement amounts but as an infusion, i.e., a very slow flow rate (some insulin pumps have a bolus mode, but these are for very small quantities). Then you have the issue of refilling the syringes - which at 40 times per min X 50 ml is a very large syringe for these pumps, to start with - at least the ones that I am familiar with.

The second issue and it is one that disadvantages the use of a peristaltic pump as well is that they are also designed for relatively slow flow rates and I don't think that you will find it easy to get a pressurized bolus, which is what it sounds like you want.

A solenoid valve is a cheap possibility https://www.amazon.com/Electric-Solenoid-Normally-Solid-U-S/dp/B00APDNPXG/ref=sr_1_1_sspa?crid=LD267GALHYWT&keywords=solenoid+valve+12v&qid=1578116721&sprefix=soelnoid+valve,aps,142&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyRkcxWkhaVE5aNzVTJmVuY3J5cHRlZElkPUEwMTczNzMwMUEwOEVLTjNNTDNMUSZlbmNyeXB0ZWRBZElkPUEwODczMTc2TFBWUTUySDBQQ01IJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

but the liquid needs to be under some pressure and you have to deal with very small/partial operations of the solenoid. Don't know how close you could get to a 5% error. It would be nice if there were some kind of plunger pump where you could operate it at less than one stroke.

What do they use for automatic paint mixing or squirting food-like substances on prepared foods?

Just my thoughts...what is the "machine" do?

Thanks so much for input guys.
Yes a syringe pump would not work in this situation as needs to be strapped to the ag sprayer and needs to deliver the chemical within a second or so to the stem of the plant and then move onto the next plant.
A dosing pump would be ideal and yes they are expensive.

I have used automatic fill vaccination syringes before but leads to fatigue of the wrist and hand as well as carpal tunnel syndrome down the road. Basically wanting to replicate that with a small motor. I have found this on Alibaba, which they claim is a dosing pump, which kinda fits what I need and runs on DC 12 v as well as has a regulator and one way valve system similar to a manual plunger.

**broken link removed**

**broken link removed**

Hopefully they get back to me on Monday. If this ends up fitting my needs, then next have to figure out how to sort out a controller to squirt out the chemical.

Is it possible to calibrate the facet/ solenoid pump to 5ml per stroke and deliver on demand?

I'd back Alex_t's suggestion of a peristaltic pump.
It's infinitely variable volume and little to go wrong.

eg. From a quick ebay search:

Possibly driven using a DC or stepper motor with an added gear reduction stage, so it takes a reasonable time or number of steps to deliver the amount of fluid you need, if a direct drive does not give adequate repeatability.