DIY dosing pump

[kevin_mic]

Just thought I would share a project I am working on and see if I could get some input.

Here is a picture of what it is and how it works.
http://www.utahreefs.com/forum/uploads/20061113_152444_diydosingpump.jpg

So basically you have a small motor that goes fairly slowly. On the little gear piece I made an acryic piece that fit and drilled holes in that piece for various dosing rates. Then I took a piece of steel rod (any rod will work) and bent it to stick in the hole, and bent the other end and hot glued it to the syringes plunger.

The syringe I fixed in place and on the end of the syringe I put a plastic T. One the other ends of the T's I put one way valves that flow the same way.

So here is the operation steps.
1. basically the motor rotates pulling the plunger out, witch creates a vacuum and pulls liquid up the line and into the syringe.
2. the motor continues to rotate pushing the plunger in. The fluid cannot go back down the line because of the one way valve so it continues up the line.
3. The process repeats and basically the fluid can never return down the line because of the one way valves.

I have done some testing with my 3 rpm motor and it produces very consistent results when operating at the same height from source to syringe to output.

Every 2 minutes on mine (trying to get syringe to use its full length) it would push about 4.1 ml of fluid. (If if was pushing the amount I thought it should it should have pushed 6 ml).

The things I don't know is how it will work over time. Namely, how long before the syringe wears out. How long before the one way valves stop working right.

Here is cost of supplies.
1. (1) 3 rpm motor -- $3.99 3 rpm motor (https://www.surpluscenter.com/item.asp?UID=2006031613352805&item=5-1563-A&catname=electric) (I know it says 2.5 rpm but that is what I bought and it is 3 rpm.)
2. (1) 1mm syringe -- $0.25 at calranch (or try a pharmacy)
3. (2) One Way Valves -- $2.00 -- One way valve from petsmart (http://www.petsmart.com/global/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524441811424&FOLDER%3C%3Efolder_id=2534374302030092&ASSORTMENT%3C%3East_id=2534374302023693&bmUID=1163450159759&itemNo=5&Ntt=valve&In=All&previousText=valve&N=2)

4. (1) Plastic T -- $0.99 from Home Depot for a pack of 5
5. Tubing -- I used rigid tubing hoping maybe it would make flow more consistant. I don't know if that makes a difference.

Also, you will need to figure out how to connect the tubing to the syringe, it is a loose fit with the tubing. I ended up using a larger piece of tubing on top of the syringe and other tubing to make a nice fit.

So in all the dosing pump would cost 7.25 not including the price of shipping and not including the price of a timer. I liked the idea of an electronic timer that would allow you to turn it off to within a minute but you could try and get it to dosing the amount you want on 15 or 30 minute intervals.

So let me know what you think.

[Tigger240]

i would be concerned with the longevity of the syringe - but could be replaced easy enough

[GSerg2]

Wow, looks neat. I say go for it.

[kevin_mic]

I am going to see if I can get it up and running tonight on my actual system.

I will start by just dosing my calcium part of my 2 part addative ( I have an IV pump dosing the alk part ). I hope to get a timer that will allow me to dose four 6 minute intervals which will give me 49 ml per day. I will have it drip into a measuring container and each day I will check the container and dump it into my tank and record the results.

After a month or two of tests it will for sure tell me how accurate it is. Unfortunatly the only way to tell if the syringe and one way valves will work (over time) is to use them.

If all goes well I might try adding another syringe in parrallel and see if the motor can handle pulling two syringes.

If it works well, I think it would be a good DIY substitute for a much more expensive dosing pump.

[Keelay]

This one is definately outside the box. I like how you think.

[pista01]

Do the syringes have rubber? I don't think the rubber would hold up long. I used to use a large syringe to dose my 2 part. It only lasted a few months before it swelled up to the point where I couldn't use it. You might want to try the kind without rubber.

Also, the syringe may wear out quicker due to the sideways force from the rod. Maybe have the rod slide a square plate back and forth, then attach the plunger to the plate. That way the plate will be taking up the sideways force of the rod rather than the syringe.

I planned on building this myself, just haven't got around to it yet.

[Harold Edwards]

looks cool, like to see pictures when you get it done

[pista01]

Something like this -> http://www.drpez.net/panel/showthread.php?t=160887

Use The Fish to translate (Babel Fish) http://babelfish.altavista.com/

[BeanAnimal]

Kevin,

I have built two prototypes of just such a pump (dual syringes for dosing 2-part). Your going to need to have the sryinge on a pivot to reduce the wear on it. In other words let the syringe "free float" between two stops. The movement will reduce the wear cause by imperfect alignment.

I used a little pivot board with a velcro strap.

The second prototype I built used a T-BAR design that was to have a reciprocating arm on it (just like a sewing machine) that would move the pistons up and down. I never finished the prototype... but had plans on using delrin and o-rings with stainless steel check balls. The design would be basically be a direct copy of a standard GRACO or BINKS piston pump.

Never saw that link before pista.... that setup looks pretty good though. Becasue he used a T-BAR setup and a wide carraige, alignment does not look like it is a problem.

[kevin_mic]

Awsome, thanks for the link. BeanAnimal -- Still not sure what you mean to let the syringe "free float" between stops.

Also, since you have done this, how long did your syringe last before you had to replace it? How could you tell it needed replaced?

[BeanAnimal]

I never ran the setup long enough to see how long the syringe would last... it was just a proof of concept.

Think of it this way. As your cam and pushrod move, the only thing keeping the motion linear is the syringe cylinder itself. Remember evn though there is a pivot point on the crankshaft and the piston, it is the piston wall that acts as the guide and forces the piston to undergo a linear motion. This works OK in a car or a train, were a secondary guide would rob horsepower more than the friction and wear do.

In our application we are looking for long life, not efficient transfer of power from a drivetrain. We need a secondary guide to keep the lateral forces away from the syringe piston or cylinder.

Setting up a lateral guide would require some extra thought and bulkiness. So instead, if we attach the cylinder on a pivot point near the end closest to the piston rod, it will "free float". As the piston rod moves in a lateral motion, the cylinder will pivot and aling with the pushrod and negate most of the lateral force. You will want to put stops on either side of the cylinder so that the range of motion is limited enough to prevent it binding up for any reason.

Bean

[douggiestyle]

you could easily make a peristaltic pump using the same motor.

[kevin_mic]

And where would one find a reasonably cheep peristaltic pump head?

[Donw]

<a href=showthread.php?s=&postid=8544124#post8544124 target=_blank>Originally posted</a> by kevin_mic
And where would one find a reasonably cheep peristaltic pump head?

I like your idea, I dont think you can find one as cheap as your project. I copied the one that was posted in the link above and used it to feed rotifers for 5 months before I took down the culture tanks. I did have a hard time getting the exact dosing but that was just with a cheap timer and trying to dose tiny amounts. I dont think you will have a problem with two part. I gave it to a friend for rodi / kalkreactor dosing and its still working I'd guess about a year later on the same salifert siringe.

Don

[mhj1580]

they already make syringe pumps for medical/ research I would see if you could pick up one of them cheap.

here is a google search for syringe pump
http://www.google.com/search?hl=en&lr=&q=syringe+pump+used

[kevin_mic]

I have looked at syringe pumps before, but I don't think they would work. Problem is I think they only push fluid out, not pull fluid in. So all you would get is one push before you have to reload. Problem 2, as with the current dosing pump I have there is too much medial crap/Circuitry associated with it so when it stops working your only choice is to throw it away.

[douggiestyle]

make a head. a couple of sealed bearings. a plate to mount them on and a pvc tube to stick it in.

you can get a peristaltic pump for a drill at $10-$15.
its not like its some type of "extreme Engineering" project.

it was just a thought.
go with the syringe.

[kevin_mic]

Sorry, I didn't mean my question to come across as rude. I have looked for peristaltic pumps before and didn't seem to find anything that was cheap. So I was just asking where to look. I am more than open to suggestions on how to do a diy dosing pump. I just was hoping for a cheap accurate alternative to the medical pumps, or the 80-300 dollar pumps I find on ebay.

[BeanAnimal]

doug I would be worried about tolerances... i suppose that the OEM stuff has gone through a lot of trial and error.

At one point I had thought of building a DIY peristaltic... but realized I would end up spending more than buying a $75 head that was already tested and had the bugs worked out. Neat idea though.... 3 bearings on a machined disc was what I had planned. The race for the tubing was to be machined as well. Don, let us know how that pump works. I am on the verge of ordering myself.

I keep going back and forth between the idea of a peristaltic, piston, and air driven dosers. Just can not make up my mind.

[douggiestyle]

i suppose tollerances would be a concern. dont want the tubing to break all the time.

those little pumps that sell for $89. figure the dealer or distributer is making a 50% margin on it, maybe more.
so like $40. shouldnt be tight tollerences.

couple nylon bearings, and a housing. no race for the tubing.
i would think the hardest part would be connecting the thing to the timer motor.

that multi syringe thing is pretty wicked

[TropTrea]

2.5 or 3 RPM pump for $3.99? Where did you find this? I have several ideas for something like that if it has enough torgue.

Dennis

[kevin_mic]

Link was listed above -- Its at www.SurplusCenter.com -- The motor I gave a link to says it has 14 pounds of stall torque. There are other motors that are cheaper but I tried one of those and it didn't work so well.

[joshuaroot]

i like it, good work!!

[Jester]

good stuff... keep us updated...!!!!