Peristaltic pumps

  1. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    As per my user name, I brew beer as a hobby. As the kit is mostly on the level and there are processes where I recyle the wort between heat exchanger and mash tun then I need pumps.

    Small brewing pumps are expensive noisy and generally cr@p at priming and being able to keep them clean. The pumps also need to be able to withstand boiling water. Currently I'm using 12v pumps that are used to recirculate boiling water arounf solar thermal panels, cheap and adjustable but you cant take 'em apart to clean them. I've also tried flojet pneumatic pumps and a Totton, I haven't tried a march may which are over 200 quid but by all accounts they are onlys slightly better.

    One guy converted some Landrover brake drums into a pair of peristaltic pumps. These are the kind of pumps that are used for kidney dialysis and precise dosing in chemical processes. Basically they are a piece of flexible pipe in a cylindrical holder and a rotor goes around squeezing the pipe, pushing the liquid around. Chemical/medical pumps tend to be very expensive and only a few litres per hour, I need them to variable between 2 and 10 litres per minute. With only a length of pipe in contact with the liquid then they are extremely easy to clean and prime easily.

    I'm at the early design phase, something similar to brake drums but in alloy would be a good start, probably 8 to 10" diameter. Then I need a motor that I can adjust in speed with quite low revs, probably geared down. I will have to experiment to work out the exact flow, I will probably be using 1/2" bore silicon tube and probably 3 or 4 rollers on the rotors to minimise pulsing. Silicon tube doesn't collapse at boiling water temp and its what all my brewery is plumbed in.

    Andy ideas on sourcing parts cheaply welcome ;)

    Cheers
    Andy
     
  2. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    15,279
    Location:
    East Yorkshire
    First thoughts are it will have spin at sone rpm to get you 10ltrs a minute, using 1/2 bore pipe
     
  3. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    I guess it will also depend on the diameter of the pump too. I would settle for a few litres less, say 7 or 8 top end if it meant the size/cost were contained and could increase the pump pipe diameter too - I need to do the theoretical figures

    Anyway - back to finishing this bottle of port ;)

    Happy new year!
     
  4. KemppiFrog Member

    Messages:
    3,210
    Location:
    Aquitaine
    I used to have a hand driven plastic one, would have suited your purpose, but can't for the life of me remember who made it. Black & Decker?
    You will need wheels on the end of the rotor.
    A quick calc gives the volume of tube at 12mm means 8.850 mtr for one lt. so for 10lts It is over 88.8 mtrs of tube. The periferal speed of your rotor needs to cover that for the top flow/min not counting losses.

    Think I got the 0s right.:laughing:
     
  5. kelsham Forum Supporter

    I used to work for a company who used such a pump on a dyeline printing machine. It used a silcone hose to carry the developer fluid.
    It was only a low volume pump, when it failed due to the silicone hose splitting it used to lose a small amount of fluid before it stopped pumping.
    It was situated above the tank, so could not syphon all the contents out.

    Kels.
     
  6. mr_splatter

    mr_splatter Member

    Messages:
    133
    Location:
    Buckinghamshire, UK
    Hi,
    A long time ago I used to work for this company on the design side of this company -www.watson-marlow.com although not mechanical. Most of your thinking is sound in particular the ease of cleaning. The flow rate you are after is quite high though with the tube size. Also if you run these pumps at high speed this wears the tubing quickly. Most of the heads I remember had two rollers sprung against the outer guide. Their pumps are expensive new but I have seen them on eBay before. The idea of using a brake drum is good though and could work. I only worked on the smaller microprocessor controlled pumps but they used DC motors with PWM speed control through an H bridge. The motor had a slotted disc on the shaft for speed feedback. I remember they would run the head at between 2 - 220rpm through about a 6:1 reduction gearbox if my memory serves me.
     
  7. Rudi McAnichal Member

    Messages:
    335
    UK
    I have seen a very simple peristaltic pump with a rotor, but no stator. The tube (neoprene, about 1/2" bore and 1/8" wall thickness) was lightly tensioned, so that it pinched closed when in contact with the rollers.

    Pros: Very cheap. No need for precision manufacture, works even if the rotor is put of true. Flow rate can be increased by fitting several tubes in parallel.

    Cons: Low pressure (it was delivering liquid at about 5-7psi, and presumably any major constriction would cause liquid to leak back at the pinch points). Increasing the tube tension would probably allow higher pressures, but reduce life of the tube.

    This pump was on an experimental crop sprayer (hand-pushed wheel barrow type) designed by ICI Plant Protection Ltd around 1971. I’d be interested to know whether anybody has seen anything similar, or has information about the tube life with this arrangement.
     
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  8. DrNik

    DrNik Heath Robinsons long lost son

    i have seen some time ago at the local scrapyard an industrial washing machine with dosing pump the way discussed, i'll keep my eyes peeled if i see one i'll nab it for you
     
  9. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    Thanks for all the ideas and suggestions guys.

    Here's photos of the pumps another brewer has made out of landie transmission brake drums

    I think this was a prototype

    [​IMG]
    [​IMG]

    I think this was testing
    [​IMG]

    and the finished product showing the brake drums
    [​IMG]
    [​IMG]
    [​IMG]

    all 3 can pump 25 litres if used together, so around 8 litres a minute seems to be achievable per pump.

    Cheers
    Andy

    EDIT - missing image bracket added
     
    Last edited: Jan 2, 2013
    Maker likes this.
  10. penfold

    penfold Ambassador plenipotentiary

    Messages:
    2,119
    Location:
    Argyll and Bute, God's own country.
    You could try wiper motors, or electric window motors, but I'm not sure how durable they would be. Alternatively, perhaps try gearing down a mains motor using toothed belts(tiny motor pulley and massive fabricated drive pulley, out of plywood or similar; because of its size, the drive pulley does not need teeth), or a cascade of bicycle chain and sprockets as duff bikes can be pulled out of skips readily.
     
  11. mike 109444

    mike 109444 Member

    Messages:
    4,254
    uk Bristol
    I work on medical equipment aka endoscopy washer disinfectors. The machines I work on have a 24v dc motor and gearbox (6 per side for scope + 3 chemical pumps shared, 2 sides to machine total 19 pumps) 2 fast pumps 310 rpm output 4 slow pumps 48 rpm (per side) plus chemical pumps. The pumps use the two roll mechanisam and the output is aprox 400ml per min from a 4.8mm bore pump tube. The pump tube is held against the roller with a nylon type material clip/strap (holder). The pumps are designed to be "serviced" so take seconds to remove the pump tube and holder for replacement. Although not the sort of output you are looking for I will get some pics of the parts such that you might be able to scale up. The pump tubes feeding the water to the scope are made of a tube called "medpure" and the ones carring the chemical (pericidic acid or clorine) are made of "tygon" which is very good at resisting chemicals and the ware and tear of operation in the pump. These pumps ect run 8 plus hrs a day 5 days a week for 6 months befor we replace them.
     
  12. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    Thanks Mike, sounds interesting :clapping:
     
  13. petedut Member

    Messages:
    86
    Sunny Wigan U.K.
    I know its not going to help your project but the pump I use for my veg oil is called a Tam105. It can handle heat, can be stripped (never personally done it) and will pump 30lpm.
    They are 240v though if thats a prob?
     
  14. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    Thanks fior the info. They pose the same problem as most of the ones used in the brewing industry, also flow rate is high and I would have to put a bypass valve on it to control it. The little solar pumps I have are good for now, not ideal, but will probably last until I get around to building a parasitical pump.

    This is a picture of a Totton pump that is food safe to around 70c and often used in brewing for some of the functions, often used in pub cellars too. To control flow I've added bypass valves and bleed valves to get rid of airlocks but still a sod to prime and prone to cavitation especially at higher temps. Solar pumps are cheaper and better at priming but still not very good. March may pumps are food safe to 100c but evidently suffer from similar problems. The holy grail is peristaltic, I hope :D

    [​IMG]

    Cheers
    Andy
     
  15. mike 109444

    mike 109444 Member

    Messages:
    4,254
    uk Bristol
    The attached pic are of the pumps in the machines I work on. The machines have to have a daily self disinfect which runs the water up to 82deg for 15mins.
    The motors are 24vDC adn each pump is protected by a 630ma fuse so they draw a lot less than that (aprox 400ma). Although the flow rate is perhaps not what you are after they are at least working pumps so you could up scale the design. Looking at the "brake drum" design I thing they lack any form of pressure spring for the rollers so are pressing the rollers on the tube with no give. In my pics you can see the spring wire. There are 4 in total 2 frount 2 rear which allow the roller some give. In use these pumps produce 1.5bar and are able to produce more (2+bar?)they are limited by pressure switches to protect the equipment they are being used on. The design is such that it takes only seconds to remove the pump tube and it's holder for servicing/replacement. These pumps run aprox 8hrs a day 5 days a week. The pump tubes and holders get replaced every 3 months (but could run longer) as preventative maintenance.
     
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  16. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    many thanks Mike. :clapping: That has given me lots of ideas, all I need now is 8 days in a week :D I have about 6 projects on the go (not counting house DIY ;)) so may take me a while to get around to it. I like the idea of spring tensioned rollers. I'll keep my eye out for some suitable motors and gearboxes or i may consider a compressed air drive.

    Cheers
    Andy
     
  17. piman Member

    Messages:
    1,732
    Location:
    Oswestry Shropshire
    Hello Brewdexta,

    all pumps are expensive but centrifugals are the most common and generally work well.

    Apart from our cask filling machine, which is a peristaltic, basically so we can pump to a specific volume, we use centrifugals, albeit stainless steel cased.. They are cleaned after use by pumping a cleaning fluid through them then a rinse with clean water.

    You can probably find some on E-bay for a reasonable price?

    Alec
     
  18. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    Hi Alec

    I currently use magnetically coupled centrifugal pumps, most food safe pumps are, for example these from March May in both polysulphone or stainless. The ploysulphone are the cheapest but are well over 200 quid and still are a pig to prime and clean. There are thousands of homebrewers scanning ebay for food grade/hot water pumps so no bargains to be had and IMHO they are still crap.

    I too use cleaning fluid to pump around the kit, I use a hot solution of sodium percarbonate oxygen based cleaner (you can buy it for £££ from brewing suppliers or pennies if you buy unperfumed stain removing powder from Lidl) followed by hot water to rinse and then sterilise with a mixture of Dodecylbenzenesulfonic Acid and Phosphoric Acid (starsan is the brand name)

    The issue is that being a home brewer its weeks between brews so anything stuck in the rotors of the pumps tend to fester, bits of hops and malt etc. I have filters etc. however some stuff gets through. Even after an hour of pumping boiling cleaners around they still can contain crud unless you dismantle them.

    I move the pumps around a lot as they are used in several functions, I use a method called HERMS (Heat Exchanged Recirculating Mash System) to allow stepped mashing, precise temp control and very clear wort. So I use 2 pumps simultaneously to transfer hot (circa 66c) and boiling liquids from one verssel to another, sparge, recirculate, cool through a plate heat exchanger and finally aerate through a sintered stainless "stone". Each time you mess with the pumps, air can be introduced blocking flow and bleeding air when there's hot or boiling liquids is no fun. I did get a couple of litres of 66c water over my plums a while ago when I forgot to close a tap and took off a quick release fitting to clear an air lock.:o

    So I'm going peristaltic at some point, just a matter of designing and building them with all the other stuff going on :D

    Here's a picture of the brewery I've built so far, 80 litres of beer a go so definitely a nano not a microbrewery.

    [​IMG]
    [​IMG]
    mashing
    [​IMG]
    boiling in the copper (well SS :) )
    [​IMG]

    pumps - these are DC pumps typically used for solar thermal panels. I keep the pumps low to minimise air locks
    [​IMG]

    pump controlled using tattoo power supplies
    [​IMG]

    Here's a pirate bringing precious hops from the new world with a cargo of beer kegs behind her
    [​IMG]

    Here's the neighbours cows eating the spent grain - they can smell the brewery is on the go, come running and wait for hours, trouble is the mash is a bit hot when it comes out.
    [​IMG]

    Cheers
    Andy
     
  19. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    15,279
    Location:
    East Yorkshire
    That's some setup, how much are you brewing at a time.
     
  20. brewdexta

    brewdexta Forum Supporter

    Messages:
    3,863
    Yorkshire
    Only 80 litres, although I can stretch it to 100 litres if I'm brewing something around 3.8% by liquoring back (adding cooled boiled water to the fermentation vessel after the main boil in the copper).

    So not commercial scale allthough some microbreweries use something similar for testing new recipes. Probably just about enough for a smallish pub if you brewed most days. I brew about once every 5 or 6 weeks unless I'm having friends over or there's party coming up. I have 8 x 20 litres SS pressure kegs and bottle some too.

    A lot of microbreweries use reclaimed small dairy vessels, that would be the next step up for me. Lots of SS welding needed then,

    Cheers
    Andy
     
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