conpewter

Recipes 

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"People should not be afraid of their governments. Governments should be afraid of their people." - V

Primary: Pumpkin ale, Pumpkin wine
Secondary: Shady Lord RIS, Water to Barleywine
Kegged: Oatmeal Stout, Living the Mild Life, Thunderstruck non-oak aged IPA, Sweet stout, Smoked Porter, soda water
Bottles: July Moon Riesling, Black Pearl Porter, Hobgoblin (II), Apfelwein, Apfelwein w/ Nottingham, 999 "Small" beer, 999 Barleywine, Oatmeal Stout, Robust Porter, Robust smoked porter

beerthirty

Recipes 

Your specs are indeed impressive. I built one a couple years a go, but had problems with tubing creep, so discarded it. I would run the motor slower simply due to the fact that the only two real factors for the tubing life is the number of compressions and the heat cycle you get with each compression. Due to these concerns I found this single lobe pump(way overpriced) which would give about three time the life of a three lobe pump. Eccentric Pumps, LLC
If any of you CAD geniuses could do something like this we would all be in heaven. It seems like it would be easier since we a talking a complete circle instead of a partial one, but what do I know, I'm not a CAD genius.
Also agree with conpewter 2 gpm would be just about perfect.

__________________
primary- Tangerine Dream, SWMBO slayer,
serving- amber ale hop experiment #6, Roggenbier, apfelwine
planning- Cru?
conditioning- 9/9/09 barleywine
Drink water?... Never, fish fornicate in it.--- W.C. Fields
Most problems can be solved with the proper application of force.

BrewBeemer

Recipes 

Very nice Eccentric Pumps, thanks for posting beerthirty.
Their 2.5 GPM pump looks like they use a sprial for the 360 degree roller contact. They keep mentioning friction of a shoe or slider vs a roller generating heat to the tubing. The original thread starter has rollers hence no added friction or heat buildup.
The smallest unit at 125 to 150 PSI wow, plus the 65 pounds weight, i'm afraid to ask what two of them would cost. I bet more than my last couple home made brewing systems in total costs. Would be nice especially as a double pump single unit design.
With in and out fittings for their hose connection this would eliminate the tubing from creeping around in the roller direction, just an opinion here.

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"Islander".....=o&o>.....

Yorg

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Yep,the eccentric design looks very good.
+1 Appeal for CAD Geniuses.
As for the tubing. The right stuff is Norprene Tubing (not neoprene):

http://www.sdr.com.au/tubing.html

uncia

Recipes 

The 5 gpm eccentric pump requires 750 in lbs @ 150rpm (~1.8HP ). This may not be all that cheap after all. That said, I am pretty sure I don't achieve the 7 gpm that my march pump is speced at so 5 gpm may be overkill.

Smeller

Recipes 

Here is a link to a Danish guy who has built a peristaltic pump, with 2 rollers

Teknik

silverbrewer

Recipes 

It looks like "tecnic" made his wall by hand, proving cad is not the be all and end all! The single roller idea is very good and does everything it says on the tin! It works fine as long as the setup has sound bearings and is well engineered, as the forces of squeezing the tube are not counteracted by other rollers, so a continual sideways strain is created that will be no problem as long as the bearings are nice and massive. Also the tube MUST overlap so the single roller always completely squeezes the tube at some point or the pumping pressure is lost. (unless a non return valve is introduced into the system, this is what I did on my mates farm pump that was a single roller affair using an old compressor crank and crankcase, and we could not overlap the tube. we can't use non return valves though, so don't even think about it.) A good starting point for anyone thinking to use the single roller approach would be to use the crankshaft and crankcases of a small motorcycle engine, (say Honda cub 90 or 125 cc single) and put the tube around the inside of the crankcase where the generator flywheel used to live. This gives an easy way of getting nice big bearings and a concentric wall to run the tube on, with a potential for about 2 usgpm or thereabouts.

On my wooden Mk1 effort, before the rollers get to see the water and are struggling to pump just the air, there is a very slight "cock up" somewhere that allows a tiny amount of air to pass the rollers. I think it happens as two of of the rollers pass the tube entry points nearly at the same time, and have to rely on only the single roller and the quality of the bearings to keep the tube squeezed. This means that to get the priming ability with only air in the system I need a good amount of revolutions to counteract the slight leak...once water gets into the tube, all is well. This proves that quality construction is paramount! With no air leak, this type of pump should suck air with no problem and self prime to several feet or more, so back to the drawing board. My skateboard wheels need to be about 1/16" wider to ensure a complete squeeze, so my slight air priming problem is sorted.

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Blessed are the "cracked", for it is they who let in the light.

beerthirty

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Heat buildup will occur even with rollers due to compression and expansion. Take a balloon and stretch and release it several times in rapid succession then feel the temp of the balloon. It is much warmer. Although each stretch cools it, the release heats it back up. Unfortunately it is easier to heat than to cool, so it gets a little warmer with each cycle. As it gets warmer the rate of deterioration increases, therefore the cooler it can run the longer it will last. With fewer rollers you reduce the heat cycle.
The pumps in the link are indeed expensive. I priced one out at $1800. Way out of my price range. But I did like the design and it seems like it would be just as easy to build as any other style of peristaltic as long as the housing can be centered.

__________________
primary- Tangerine Dream, SWMBO slayer,
serving- amber ale hop experiment #6, Roggenbier, apfelwine
planning- Cru?
conditioning- 9/9/09 barleywine
Drink water?... Never, fish fornicate in it.--- W.C. Fields
Most problems can be solved with the proper application of force.

BrewBeemer

Recipes 

Look at the replacement tubing they are asking for the Eccentric Pumps company. The price of one tube is way more than one March pump, damn what a deal killer of a pump purchase besides replacement tubes by them.
Maybe ok from a manufacturing company that has deeper pockets than you and I as only home brewers.

__________________
"Islander".....=o&o>.....

beerthirty

Recipes 

Ya I know, it was such a nice design I thought I would share it. Perhaps give some people ideas, but not about buying one.

__________________
primary- Tangerine Dream, SWMBO slayer,
serving- amber ale hop experiment #6, Roggenbier, apfelwine
planning- Cru?
conditioning- 9/9/09 barleywine
Drink water?... Never, fish fornicate in it.--- W.C. Fields
Most problems can be solved with the proper application of force.