My Modified enteral feeding pump

[mloebl]

To make a long story short... I had bought a peristaltic reef modified pump a couple years ago, and had it fail on me once since it's gears I think need to be greased as it was sticking a bit. Figured I'd go in and lubricate it, but then found out the person who modified it put in security bits, so couldn't get in . Emailed the company but never heard back, so I made it my mission to try to make my own. My current pump has a float switch jack in the back, so I wanted to have a replacement pump to do the same thing.

Off to ebay... I won a pair of them for $134 shipped. Yes, TWO... So figured one to play with if I blew it up... Worst case it was still 1/2 the cost for two of them what I paid for one.

Here's the model I got all done being modified pumping away:

I powered it up, and quickly ran into a problem... it was smart enough to have a drip sensor so kept shutting off. I'm a basic electronics person and NO expert, so spoke with a friend of mine who helped me out. After disassembling, I found it was a simple beam that needed to be broken every few seconds. I metered it and the transmit side was 12v dc, and on the receive side it was going between 0 and 5v. So I ordered a simple 555 timer kit that was adjustable. The 12v dc was enough to power the kit, but not enough to drive the relay which needed 100ma. The power supply put out 24v ac, so ordered a very small and cheap 24vac to 12vdc transformer. Soldered it in, ran the wires... and heard the relay firing. I adjusted it to fire every few seconds for 1 second hold. I attached the relay output to the receiving side of the drip sensor, and it worked. Here's the inside after cramming it all in:

The transformer is hot glued above the battery, and the 555 timer is to the right.

cont....

 

[mloebl]

Now for my next challenge... the float switch. This turned out to be a lot more complicated than I thought. I was hoping it was a simple DC motor I could just cut the circuit to install a switch. Unfortunately the motor had 8 wires to fire magnets for the motor, so no easy way to break the circuit.

Here's what I was up against:

My friend looked it up, and found the chip controlling the motor had a disable pin. To shut off the pump, all I needed to do was set this pin to ground. After doing some desoldering... I was able to remove the disable pin from the PCB, and solder in two wires to connect to a standard 3.5mm mono audio jack.

Finally I drilled a small hole in the back for the jack. If the circuit is closed with a float switch, the pin is grounded, shutting off the pump:

Here's the rundown of what I needed:
Enteral Feeding pump: $67 shipped
555 Timer kit: $8.74 shipped
24v to 12v converter: $20.83 shipped
3.5mm jack: $2.50

I'm sure someone a bit more electronics saavy could have done it cheaper, but I'm pretty happy with the results

-Mike

 

[Jim Tansey]

Why not use a standard feeding tube and keep the drip function?

Jim

 

[rtc_reefer]

Brilliant! I admire you!

 

[mloebl]

Why not use a standard feeding tube and keep the drip function?

Jim

Hi Jim,

I pull from a 55g drum of RODI, and the pump sits on top of it. No real easy way I could think of to use the drip bag.

-Mike

 

[pantinor]

its cool. what is it for? enteral feeding? are you dripping kalk with it?

 

[mloebl]

its cool. what is it for? enteral feeding? are you dripping kalk with it?

I got the idea from seeing Paula's tank; I use it for ATO and Kalk dripping thru my reactor. However you could dose pretty much anything. It's adjustable from 1ml to 295ml/hour. One cool feature of them is they do have backup batteries built in that will run for several hours.

Since I have the reworking down to a science... (took about 30mins to modify the 2nd one) I now have two of them I was going to add the second one to my fiancee's tank doing ATO there, but since it's in the office area, I don't want to listen to the relay when on the PC, so changed my mind. I thought about using one for controlled dosage of feeding as well where you add the food in the morning, and it slowly adds it all day, but not sure if that's worth the effort or not.

They also (unless the silicone tubing snaps), won't siphon water if the destination is lower than the source tank. I placed my current one on the top of a 55g drum, which is higher than the level of my sump. It won't siphon and only push the water amount I want, and if the tubing ever snaps, being above the level of the 55g drum it won't spill out anywhere.

I suppose lastly... just wanted to see if I could do it myself for cheaper

-Mike

 

[pantinor]

Is this better than a gravity fed drip supply? What do you gain by using this pump? You mentioned a float switch that needed to be modified.

 

[mloebl]

Is this better than a gravity fed drip supply? What do you gain by using this pump? You mentioned a float switch that needed to be modified.

For dosing with the kalk reactor, I find it works very well since I only want a reasonably low-controlled flow going thru it. The pump by design does not siphon water, so doesn't matter as much where the pump is located. If your destination tank is lower than your source tank of water, on most pumps if the pumps shuts off, once it gets the flow going, the water will continue to flow down to the lower tank. With a peristaltic pump, it keeps pressure on the line by wrapping around the wheel (not sure of it's technical name), so when the pump wheel is not moving, no water can flow. I did the float switch so for auto-top off of the sump water, the float switch can turn on /off the pump depending on the level of the sump.

-Mike

 

[ziac]

I recently got a pump and it has the drip dector working also i have found a place with the 555 kit but they are out of stock I was hopeing you could post link to where you got your 555 kit of the transformer ? I was also hopeing you could tell me how to tell what side is the send and what side is the recive so I would know what side to hook the 555 to I only need to disable the drip dector so i can dose 2 part thanks

 

[mloebl]

Hi Ziac,

I got the 555 timer from ApogeeKits. I found the transformer on eBay, VID-2412CONV (they are used for CCTV.)

Good luck!

-Mike

 

[mloebl]

Sorry, just noticed your second question; I had to meter it to find which side was send and which was receive as both the diode and sensor looked pretty much the same to me. One side outputs a steady 12v which in theory should be the send side, and the other side will not have a steady voltage; it should change depending on whether it's receiving anything from the diode.

-Mike