# Peristaltic Pump



## Ginger NZ (4/12/07)

Hey guys, apologies if this is old news but it gave me a bit of a think last night. I read someone saying that peristaltic pumps were very expensive and I was surprised given how simple the mechanism is. The principle is that by squeezing the pipe and running the liquid along (sort of like squeezing the last toothpaste from the tube), you can pump without making contact with the fluid.

I saw a hire sprayer in my local garden centre on Sunday. On closer inspection it appeared to be based on a simple peristaltic pump. 

It consisted of a metal disk, 3 bearings or stainless steel spacers and some flexible pipe fixed to a cart or sack barrow. 

The bearings were located in an equilateral triangle on the disc and the pipe was run tightly over the bearings. The pipe ends were fixed to the frame of a cart and the disc was attached to the wheel. Rolling the cart caused the disc to spin and drove the liquid along

It set me thinking that it'd be easy to modify this design to include some beerline attachments and maybe a handcrank made from a couple of bicycle sprockets or even have it directly driven from a hand drill. It might be an option for some of you guys that filter beer. I think I'll bodge one together to remove the need for syphoning. 

Sorry if this is a bit confusing or if you all know it already, I needed to get it out of my head. 

PS. I think this is my first post, hey everyone!


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## Jye (4/12/07)

Welcome to AHB Ginger  

There has been a bit of discussion on them but the main problem is finding a commercially available one with a high enough flow rate and doesnt cost an arm and a leg.

Heres a few threads to help you with your project.

My pump
Jonathons pump
Craftbrewers pump


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## Ginger NZ (4/12/07)

WOW, some awesome work there guys. Definitely out of my league technically!

Thanks for the welcome


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## LethalCorpse (9/1/08)

Ginger NZ said:


> WOW, some awesome work there guys. Definitely out of my league technically!
> 
> Thanks for the welcome


Nah, I don't know about that, ginger. I've been thinking a lot about it myself in the past few days, and am convinced it's feasible using cheap materials and hand tools. The body, for example, could be made out of several layers of MDF cut with a scrollsaw or jigsaw, and sandwiched together. The rollers could be chair-casters, stacked ball-bearings, or needle bearings. If the disc had slots instead of holes to mount the rollers, you could move the rollers depending on tube thickness - and that can be done with a few drill holes and the jigsaw again. The motor could be a handdrill, because they're already geared and designed for speed control at about the speeds we're talking, or a more sophisticated speed controlled motor. I'm even thinking of putting in a sprung hosebarb on the inlet side to prevent hose creep as it pumps, and adding sprung rollers to prevent it jamming if solids get in it.

Wanna help me flesh out the design? Let's set a cap on it at $100 for parts, and no tools more expensive than a dremel? I reckon we can stay well below that. 

Of course, I'd also be interested in some more data on that sprayer you saw. You might be able to pick up the whole unit for very cheap, and all you gotta do is attach the drill. I see no reason why it wouldn't work for beer if it works for pesiticides etc. See if you can take some photos, and more importantly, get a brand name.


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## browndog (9/1/08)

LethalCorpse said:


> Nah, I don't know about that, ginger. I've been thinking a lot about it myself in the past few days, and am convinced it's feasible using cheap materials and hand tools. The body, for example, could be made out of several layers of MDF cut with a scrollsaw or jigsaw, and sandwiched together. The rollers could be chair-casters, stacked ball-bearings, or needle bearings. If the disc had slots instead of holes to mount the rollers, you could move the rollers depending on tube thickness - and that can be done with a few drill holes and the jigsaw again. The motor could be a handdrill, because they're already geared and designed for speed control at about the speeds we're talking, or a more sophisticated speed controlled motor. I'm even thinking of putting in a sprung hosebarb on the inlet side to prevent hose creep as it pumps, and adding sprung rollers to prevent it jamming if solids get in it.
> 
> Wanna help me flesh out the design? Let's set a cap on it at $100 for parts, and no tools more expensive than a dremel? I reckon we can stay well below that.
> 
> Of course, I'd also be interested in some more data on that sprayer you saw. You might be able to pick up the whole unit for very cheap, and all you gotta do is attach the drill. I see no reason why it wouldn't work for beer if it works for pesiticides etc. See if you can take some photos, and more importantly, get a brand name.



If you are going to do it on the cheap, I reckon you should make it hand wound and a big diameter. I have one of craftbrewers peristaltics and I can tell you they need a bit of torque to run them. you could call it a Bicepbuster

cheers

Browndog


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## LethalCorpse (10/1/08)

what I'm trying to get my head around now is how to keep the hose centered in the race without touching the main disc.


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## LethalCorpse (14/1/08)

Retaining arms to either side of the rollers as seen on Jye's pump should do the trick. I also thought of roller-skate wheels for the rollers, and a pair of skates can't cost that much. Next challenge I'm considering is fixed, adjustable, or sprung hose compression, and the attendant difficulties of all three.


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## LethalCorpse (16/1/08)

I wonder if a mod might be able to move this thread to gear and equipment. It might get more attention there.


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## PostModern (16/1/08)

'Tis done LC.


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## LethalCorpse (16/1/08)

Champ, cheers PoMo


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## mika (18/1/08)

I like the lemmings avatar, think it has a relation to your thoughts on the pump though. As Browndog has mentioned, they require some torque. Certainly wouldn't bother with sprung rollers, it's only going to work against you and add to cost, if that's your end result. No commercial peristaltic pump I've seen has that kind of protection. That's part of their advantage, to be able to pump tough stuff. Ball bearings too thin, needle rollers OK, but now you're talking about machined metal spindles and you've got to retain the bearings somehow. The drive shaft even if made into a 2 or 3 roller design is going to be subject to some significant bending forces and going to need a serious bearing and there's that steel again.
If you had a lathe in your back shed and a bit of scrap steel, less than $100 is certainly achievable. Otherwise I personally think you're stretching it. Feel free to prove me wrong.


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## altstart (18/1/08)

mika said:


> The drive shaft even if made into a 2 or 3 roller design is going to be subject to some significant bending forces and going to need a serious bearing and there's that steel again.
> If you had a lathe in your back shed and a bit of scrap steel, less than $100 is certainly achievable. Otherwise I personally think you're stretching it. Feel free to prove me wrong.



I dont want to rain on your parade but I agree with Mika here. I do have an Australian made metal working lathe in my shed a Hercus and I have spent some time trying to set up one of these pumps. There are all sorts of issues with precise clearances between rollers and caseing to suit specific pipe diameters and wall thickness. Then you have the problem of driveing it, the torque required useing half inch pipe suitable for this application is astounding. You have to use the correct grade pipe or the pipe will split after a very short time and it will split when you are pumping fluids. Too much speed and driving force and you will damage your filter. In the end I decided it was taking too much of my time and I bought one from Ross at Craftbrewer. I use it for various applications in the brewery including sanitising kegs it is a very useful piece of kit.

Cheers Altstart


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## newguy (18/1/08)

I'm surprised no one has mentioned this before. You can buy peristaltic pump heads alone and they're very inexpensive. The head unit is completely self contained - you don't have to build anything or worry about clearances or stuff like that. All you need is a motor to drive it.

Just type "peristaltic pump head" into ebay.


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## altstart (18/1/08)

newguy said:


> I'm surprised no one has mentioned this before. You can buy peristaltic pump heads alone and they're very inexpensive. The head unit is completely self contained - you don't have to build anything or worry about clearances or stuff like that. All you need is a motor to drive it.
> 
> Just type "peristaltic pump head" into ebay.



I went down this road as well. To couple a motor to a pump head requires precise engineering skills if you think about it the drive shaft of the motor has to be dead centre of the pump head. Windscreen wiper motors do not work they burn out very quickly a 24 volt motor is necessary and a suitable power supply. It then has to geared to the correct speed to match the pipe size to give you the flow rate required. I bought three coin units from Oatley electronics and scavenged the 24 volt motor and gear box from one of them. After expending a lot of time fitting the motor and gear box to the head I realised the motor simply did not have the torque to drive the pump head properly. I ended up spending more than the cost of a new pump from Craftbrewer it was however an interesting experiment. Anybody want to buy a new coin unit set for Australian currency very cheap.

Cheers Altstart


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## Jono_w (18/1/08)

LC,

I'm not one to put any one off experimenting with making their own brewing equipment, but I agree with Mika and Altstart. 
I spent a fair bit of time building my pump, and with a lathe, mill and computerized mill on hand I had trouble with tolerances. There is allot more pressure on that tube than you would think. Also finding a correctly geared motor with the right RPM and torque was very difficult. I was looking at using the pump to mash with but the flow was too low, would need a couple in parallel.
I did learn all sorts whilst experimenting with it though and thats what its all about , so go for it. 

Cheers Jonathon


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## newguy (18/1/08)

altstart said:


> I went down this road as well. To couple a motor to a pump head requires precise engineering skills if you think about it the drive shaft of the motor has to be dead centre of the pump head. Windscreen wiper motors do not work they burn out very quickly a 24 volt motor is necessary and a suitable power supply. It then has to geared to the correct speed to match the pipe size to give you the flow rate required. I bought three coin units from Oatley electronics and scavenged the 24 volt motor and gear box from one of them. After expending a lot of time fitting the motor and gear box to the head I realised the motor simply did not have the torque to drive the pump head properly. I ended up spending more than the cost of a new pump from Craftbrewer it was however an interesting experiment. Anybody want to buy a new coin unit set for Australian currency very cheap.



I agree that it's often easier to buy what you need rather than try to bodge something yourself. But if there is someone with good motor knowledge along with some mechanical ability, a pump head may be the ideal solution.

Just curious - did you try a drill?


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## LethalCorpse (18/1/08)

Thanks for the input, guys, I really appreciate it. I'm too stubborn to be deterred, but it's very helpful to have the pitfalls pointed out early. 

I've seen the masterflex pump heads on fleabay, and agree that they're nice and cheap, but I reckon their flow rates are just too low. 2.3L/min would take a long time to pump the wrt around, and I don't think it would be quick enough to control temps with a RIMS (one of my main reasons for building this pump), even if I used two in parallel.

I am an engineer, so things like motor speed control etc are no real problem. I reckon I'm going to start with a cheap drill, though, and go from there if needed. The design in my head is closest to this one on a smaller scale, using ideas from Jonathons (the sandwiched layers for the housing) and Jye's (the retaining arms on either side of the rollers). I think ordinary MDF or particle board will do fine for both the main rotor disc and the surround, provided I can machine it with reasonably tight tolerances. The rotor itself doesn't need to be entirely precise, but the relative positioning of the rollers and the shaft do. This can be done very accurately using a compass, if you remember high school geometry - fix the diameter of the compass, draw a circle, put the point on the edge and then cut the first circle on either side. Repeat with the point on the place where you cut it, all the way around the circle. Gives you six points equidistant from the centre and each other, you can choose to use all six or three. Use a drill press (or a hand drill and a steady hand) to drill them, and you've got your rotor. The wheels need to be big enough diameter that they can be mounted on the rotor stably, whilst extending well past the edge of the rotor. They also need to be taller than the diameter of the squashed pipe. I reckon rollerskate wheels will do the job nicely - about the right dimensions, with decent bearings already included. I've pretty much ditched the concept of sprung occlusion - came to much the same conclusion as you mika - but I'm still debating adjustable occlusion. Two options there - one is a slot cut in the rotor for roller mounting, but this would be very tough to get all rollers mounted the same distance from the hub. Another possibility is multiple sets of holes offset around the rotor with different occlusions for each set of three/six. Would be a pain to change occlusion, but would give firm mounting each time. I've also not yet decided if I want a single rotor, or rotors on front and back. This would add a lot to the overall bulk of the pump, but would provide better structural strength. Dunno if it would increase or decrease the requisite torque.

The next part will be tougher. The housing needs to consist of a backplate, a series of layers with U-shaped cutouts, then a front plate. The front and back plate need bearings with the outside mounted firmly to the plate and the inside mounted firmly to the shaft. The U-shape needs to be an extended semicircle, with the semicircle diameter being, say, 5mm larger than the reach of the wheels at maximum occlusion. To do this, I'll need several layers of board, cut precisely and evenly. I think the trick here is to mark them all using the compass at a fixed size, then cut inside the line using a jigsaw or router (I have a triton router/jigsaw table which will help a lot, but it could be done by hand). Then clamp together and sand by hand until they're all even, and ensure I don't go past the line at any point. If done carefully, this should give <1mm variation around the U. 

Any major concerns with the method so far?


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## newguy (18/1/08)

Oh, this is for a RIMS? Get a march pump. I built my own HERMS and there is no way that a peristaltic pump would work for my system. I'm not even considering flow rates - I get grain running around the system in the beginning and I don't know how a peristaltic pump would handle solids in the 'squeeze' path. Another thing to consider is the suction of such a pump. I'm sure that its suction is reasonably good, but I can't get over the fact that the suction will collapse the neoprene (is that what it is?) tubing being squeezed, and that will mean a loss of suction. In a HERMS or RIMS, the pump's pressure head isn't as important as its sucking force because until the grain bed gets set/established, it's pretty damn tough to pull anything out of the bottom of your mash tun.

Flow rate is absolutely critical in a RIMS. A friend had one (I say had because he's now commercial), and the biggest issue he had was flow rate. Grain husks would get caught in the heating element chamber and scorch. They'd lodge which would catch more husks which would also scorch. The beer would turn into a rauchbier. Until he modified his layout a bit to eliminate some sharp turns in the plumbing, scorching was a big issue. A peristaltic pump would have to pump huge volumes/minute to get around this problem.

Seriously consider getting a march pump. And if you need any information/tips regarding the layout of the system, let me know.


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## Jye (18/1/08)

These pumps handle grain, husk, hops and break material no worries. I have used mine through out the entire brewing process (transferring of all liquids, recirculation HLT/mash/wort and for filtering ) for about 40 brews with no problems at all.

Im not sure suction has anything to do with a rims/herms, unless the pump is above the mlt, in which case you cant prime a march pump since they cant suck. If this is the case then a peristaltic pump is better since it can suck to the point of collapsing silicone tubing, the sucking limit independent of what pump is attached. And finally sucking the wort from the mlt is just asking for a suck sparge, it should flow just under gravity.

Speed control is also not an issue as long as the pump head is large enough and you use a motor with a PWM for speed control.

IMO these pumps shit all over march pumps.

LethalCorpse good luck making one, Ive thought about it and reckon it would be damn hard without a CNC router... Im just cheering I scored mine.

Jye


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## newguy (19/1/08)

Jye said:


> These pumps handle grain, husk, hops and break material no worries. I have used mine through out the entire brewing process (transferring of all liquids, recirculation HLT/mash/wort and for filtering ) for about 40 brews with no problems at all.



Now I know. I couldn't wrap my head around a pump like that being able to pass solids.



> Im not sure suction has anything to do with a rims/herms, unless the pump is above the mlt, in which case you cant prime a march pump since they cant suck. If this is the case then a peristaltic pump is better since it can suck to the point of collapsing silicone tubing, the sucking limit independent of what pump is attached. And finally sucking the wort from the mlt is just asking for a suck sparge, it should flow just under gravity.



Every batch I've done with my HERMS - and my pump is below the mash tun - the flow out of the mash tun right after doughing in is pitiful. Once saccharification starts, the flow gets much easier. Once the mash is complete, the mash tun drains easily. It has to do with the viscosity of the mash. Right after you dough in, you really have porridge. Once the enzymes start to convert the starches into sugars, the solid portion gets smaller and the liquid portion gets more dense. At this point, the whole works tends to flow much more easily. I've done quite a few decoctions and have noticed the same thing with the first pull. When you first start heating that first decoction, it's a bugger to stir because it's so thick. But once the works gets up to sacch temps, it suddenly gets much more 'watery' and is suddenly very easy to stir.


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