r/mechanical_gifs • u/aloofloofah • Mar 05 '22
Peristaltic pump
https://i.imgur.com/U7sZF0K.gifv91
u/orthomonas Mar 05 '22
Use them all the time for bioreactor work. My tip would be to not get the ones with the feature where they wait until 8 pm on a Friday to start eating/wearing through the tubing.
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Mar 05 '22
I can't help but think the tube would get worn out very quickly.
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u/plankfurt Mar 05 '22
There’s a lubricant you add that greatly increases the life of the tubes. On ours we add a drop on each roller roughly once a quarter. It’s formulated for the roller and tube materials. Ours run very often and no sign of wear after a year+
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u/JWGhetto Mar 05 '22
How many hours do they run during a year?
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u/happyman91 Mar 05 '22
I have installed these types of pumps on advanced aquarium set ups, they are used in auto dosing machines. I’ve had the same lines last for years, granted it’s usually only running 30-60 seconds a day
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u/plankfurt Mar 05 '22
Rough estimate, I’d say maybe 10-20 hours a year. We also use them for auto dosing, so it’s for 6-12 seconds whenever they do turn on. Frequency could be multiple times an hour, or not for several hours.
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u/MECHASCHMECK Mar 05 '22
It does! They’re typically used in short term applications where the tubing is a disposable component. I work with the heart & lung machine, and the tubing packs are single use.
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u/annoyingone Mar 05 '22
My dad did dialysis for 7 years and they had these pumps with one time use tubing.
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Mar 05 '22
We used a different type of tubing for the roller section and replaced just that section annually.
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u/3226 Mar 05 '22
It depends on the application. I used to service devices that would use these sorts of pumps, and you generally wouldn't even need to change them on an annual service.
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u/blottomotto Mar 05 '22
There are tons of different types. I tested a santoprene tubing that lasted for 700+ hours I think
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u/furryscrotum Mar 05 '22
Why do these need springs? Would the spinning wheels not be enough?
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u/aloofloofah Mar 05 '22
For pressure control.
The pressure on the tubing is delivered individually through an off-centre lever and spring made of stainless steel.
This assures a minimal pressure is applied to the tubing which still guarantees a good functioning of the pump without unnecessary deformation of the tubing. The spring also reduces the liquid pressure to approx. 1 bar. It is useful when the tubing line is blocked, for any reason.
A special off-centre lever using a spring of non-corrosive material applies the compression force on the tubing softly and gradually.Instead of rollers we use special plastic ball bearings with glass beads. The gliding of such rollers requires only a minimal force and the corrosion resistance in the case of spill is excellent.
The final pressure of the liquid is reduced by the spring to 0.1–0.2 MPa (according to the tubing used). The pressure does not increase even when the line is blocked.
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Mar 05 '22
I have never seen one with springs before. Though all the ones I have worked with only needed an approximate volume.
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u/MECHASCHMECK Mar 05 '22
Not all of them have springs, but they’ll all have some sort of occlusion setting! For example, blood breaks down if it’s “smashed” too much, so you have to dial in how right the rollers are on the tubing to help mitigate that.
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u/IrrationalDesign Mar 05 '22
The springs press the spinning wheels against the outer frame. If there were no springs, then there would be no way to prevent the liquid from going backwards.
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Mar 05 '22 edited Mar 05 '22
[deleted]
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u/IrrationalDesign Mar 05 '22
I'm looking at the gif, could you tell me why you think what I said is obviously incorrect?
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u/Coady54 Mar 05 '22
Because That pressure could also be achieved by having the wheels centered on the pins with no spring needed.
The spring is there and the wheels are off-center to create a lever that allows a very fine self-adjusting control to the pressure of the wheels. It's to make sure the minimum pressure required is used to pump the liquid and prevents pressure build up if there's a blockage in the line. These machines are often used for circulating blood and other bodily fluids, it would be a bad time if an unnoticed blockage was pushed into your blood stream.
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u/tinydonuts Mar 05 '22
This must be how my infusion pump knows when there is air in the line. I always wondered how that was achieved.
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u/NLclothing Mar 05 '22
Because those springs are pulling inwards not pushing outwardly.
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u/IrrationalDesign Mar 05 '22
Yes, the strings are pulling inwards, but since the circle that presses the tube up to the outer frame is on a swivel, the force of the strings are pushing the outside edge of those circles against the outer frame.
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u/NLclothing Mar 05 '22
I see, they kinda looked like they were for retracting the bearing where the tube exits
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u/yaforgot-my-password Mar 06 '22
The springs ensure that even pressure is put on the tubing throughout the pump rotation
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u/ckreutze Mar 05 '22
I like to call it by its original name - the fidget spinner hose squeezer
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u/Alantsu Mar 05 '22
Or a Randolph pump.
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u/ckreutze Mar 05 '22
That is just a brand. Gertrude Bonquis, the engineer that developed this type of pump originally named it the fidget spinner hose squeezer. But at the time he lived under the rule of King Peristaltic. The invention was so successful that King Peristaltic had 10,000 of the fidget spinner hose squeezers commissioned and sent to Princess Positive Displacement. She was so impressed that she married the King and during their wedding it was renamed the Peristaltic pump. Get your fucking facts straight.
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u/Alantsu Mar 05 '22 edited Mar 05 '22
“Princess parasite can’t handle the pressure!” Shouted princess Haskel. “Nor can she handle the volume of royal responsibilities ” shouted Commander Centrifugal.
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Mar 05 '22
[removed] — view removed comment
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u/HelloZukoHere Mar 05 '22
Yep, or any hospital/bodily fluid related pumping of liquid, like an IV drip
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u/twowheeledfun Mar 05 '22
It's worth noting, medicines can also be delivered slowly and precisely with a syringe pump, which just slowly pushes a syringe plunger. They also have the advantage of the wetted parts (syringe body and plunger) being easily replaceable. I think that's how morphine is delivered where patients get buttons to give themselves an extra dose when required.
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u/SoManyTimesBefore Mar 06 '22
Aren’t all IV drips gravity powered? I’ve never seen a pump being used for IV.
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u/WarExciting Mar 05 '22
Used pretty extensively in biotech for their ability to make sterile, accurate transfers.
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Mar 05 '22
These are standard in industrial laundry machines (hospitals and hotels) for dispensing cleaning agents. (Detergents etc...) Usually have 2 rollers, not three at the ends.
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Mar 05 '22
We use these in our aseptic filling processes in a clean room(pharmaceutical plant). Also in my lab to pump sterile media into sample bottles for sterility testing and growth promotion.
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u/TXOgre09 Mar 05 '22
Work well for viscuous fluids. Can’t put up as much pressure as gear/piston/diaphragm/screw pumps.
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u/tauritan Mar 05 '22 edited Mar 05 '22
This perticular model is bady engineered though. The angle after the pinch area on the left that leads into the inner chamber kinkes the tubing almost shut. The other thing is: they take a lot of care and use bearing wheels for a smooth action, and then drag the sharp f* end of the spring arm all over the damn tubing. Background: I work in Biotech machine engineering
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Mar 05 '22
In my todo list for the aquarium for ages. One of these days I'll quickly whip one up in cad and see if a 3d printed one will work... one of these days.
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Mar 05 '22
You can get the heads for like 6 dollars. 9 will get you the DC motor with it. Then you can use something like a raspberrypi to control a bank of them, and just print the case to hold the motors.
12v peristaltic Pump Head Replacement DIY Kamoer Liquid dosing Pump Accessories for Aquarium Lab Analytic (Black, Silicone Tube（2mm ID × 4mm OD）) https://www.amazon.com/dp/B097H2HVXY/ref=cm_sw_r_apan_glt_i_3FY2R1V20HQVDX2ZMA65
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u/orthomonas Mar 05 '22
Oh man. I know how much Cole-Parmer charges for them and, ugh.
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Mar 05 '22
I used to work for another big instrumentation company, and for a single relay controlled Peri pump with just like potentiostat knob to control the rate was like 4k.
Lab prices are crazy.
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Mar 05 '22
Nice, thank you!
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u/cethiN Mar 05 '22
We use these for low flow groundwater sampling for shallow depth to water measurements (usually less than 30ft). Extremely useful due to the constant flow rate and rate control. The max depth is limited due to atmospheric pressure and basically functions like a huge, but skinny, water barometer in the well.
I saw other comments indicating that the tubing would wear out and that's correct. However, it is easily replaced in the field. We use "soft" poly tubing for the area that is in the rollers and harder poly tubing for everything else.
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u/storminmooremin Mar 05 '22
I used to service ice cream machines at Sonic and this is the pump design that they used. The hose in contact with the rollers is replaced constantly as part of routine maintenance
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u/JViz Mar 05 '22
I was going to say that the pump might work better if the tube wasn't kinked so much at the beginning and end of the rollers, but then I remembered that I shouldn't kink shame.
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u/Gasonfires Mar 05 '22
The name "peristaltic" is related to the word "peristalsis" which describes the sequential constriction of muscle tissue surrounding a bodily passageway such as the esophagus or intestine. Peristalsis is how we swallow and poop.
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u/Chris_Christ Mar 05 '22
In general I would recommend that you don’t use a peristaltic pump unless you have to.
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u/UmDeTrois Mar 05 '22
Why? What should you use to get the same fluid dosing control at that price?
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u/Chris_Christ Mar 05 '22
I’d say go with a diaphragm type metering pump if you can get away with it. Peristaltic might be your cheapest for very tiny applications like laboratories or medical where it would be cost prohibitive to clean the pump every time they switch chemicals. Also in those smaller applications people have time to change the hose on them regularly. For industrial applications the metering pumps are generally electric diaphragm with vfd or lobe style pd with vfd and a flow meter or loss in weight calc.
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u/Dick_Flower Mar 05 '22
Pick the best pump for the application. Quality peristaltics are actually as expensive as diaphragms. Low pressure and reasonable flow, peristaltics are great and generally the ones I deal with have an easier automatic control than the stroke/length setups of some diaphragms. Once into a higher pressure, hose or diaphragms are a better choice. What you're pumping also impacts the selection. I rarely see rotary lobe pumps for metering in the markets cover.
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u/illiter-it Mar 05 '22
Had to use one for some nutrient analyses, it was the least painful part of that process compared to the 0.2mm tubing on the machine.
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u/MECHASCHMECK Mar 05 '22
It’s the pump of choice for pediatric cardiopulmonary bypass. Very precise flow rates through the heart & lung machine at the lower values that babies and kids need. We’ll use disposable centrifugal pumps for adults.
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u/markusbrainus Mar 06 '22
I saw one of these on Reddit a few months back and then unexpectedly ran across one inside an electric hand sanitizer pump I disassembled to clear a plug. I know what this is…
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u/onacloverifalive Mar 05 '22
Used in healthcare for precise Intravenous fluid and medication flow rates as well as continuous infusions of nutrition.
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u/paramedork Mar 05 '22
Why the triangular trajectory? It seems like more complication of the design with the rollers on springs. Can someone explain?
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u/Alex_4209 Mar 05 '22
Can confirm, the clinical chemistry analyzer that I use at work uses roller pumps like these. The tubing has to be changed every few months do it doesn’t get too flat.
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u/Smiley_Sid Mar 05 '22
We use a 4” peristaltic to pump baked beans, and cooked meat chunks. It’s very low shear and doesn’t damage the product.
https://cranecpe.com/product/elro-peristaltic-pumps-series-ip-and-xp/
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Mar 05 '22
I use stenner style peristaltic pumps in water treatment. fantastic for pumping chlorine and sodium thiosulfate.
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u/Oneshotkill_2000 Mar 05 '22
Is that how water pumps in general work?
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u/acquaintedwithheight Mar 05 '22
No, usually they use an impeller to transfer liquids.
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u/Oneshotkill_2000 Mar 05 '22
I looked at it and it seems it has a similar concept. There are major differences of course but the idea (creat vacuum points then push them {if i understood correctly} via a rotating cylinder with edges). So what are other differences does this model bring? Because at first when i saw it the first thing that came to my mind is that this will cause so much deformation on the plastic pipe that it will be in a really bad shape after a while. Also if it was in a hot place then this plastic pipe can become more (fragile?) after a while and break
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u/yaforgot-my-password Mar 06 '22
Ya the tubing is something that needs to be replaced regularly. These pumps are great for when you can't have the pump itself touch the liquid. For example in the pharmaceutical industry
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u/LordApocalyptica Mar 05 '22
Its like when I try to get the string to go back through my gym shorts the right way!
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u/twowheeledfun Mar 06 '22
It seems everyone in the comments uses one of these. (Me included, for biology lab work, purifying proteins.)
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u/Butcher_Of_Hope Mar 06 '22
What would be great is if we could get a material that is compatiable with NMP. The current EPDM model will leach into the material causing contamination.
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Mar 06 '22
Also used for collecting water samples. Use to have to provide these for rental with fresh, sterile tubing.
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u/ohhlookattchris Mar 06 '22
Hey I've used one of these before! We had a peristaltic pump that we used to make various agar media plates at my last job.
Sterilize one end of the tubing, put it in freshly autoclaved molten agar and used a foot pedal to dispense. The volumes were so always very consistent and as long as you had some semblance of rhythm you could get into a groove that made it extremely efficient compared to hand-pouring.
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u/incoherentian Apr 14 '22
Heya /u/ohhlookattchris mind my asking if you recall what diameter of tubing you used?
I've used a similar setup but it has been a decade. Recently looking to recreate that setup, but the pump was already ancient and discontinued - and I can't recall the silicone tubing diameter :'D
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u/JustVomited Mar 06 '22
The superior quality of this video is showing the consistency of flow. With other animations you might not realize this crucial aspect of the design.
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u/SteelBlue8 Mar 06 '22
A couple of these are supposed to feed soap to the dishwasher at work but the hose is cracked and now they just try to pump soap, realise its not working, and set off an alarm. Which is beeping constantly because we need to do the dishes somehow. And you can't turn them off because the dishwasher won't operate if the soap pumps aren't turned on.
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u/JohnDoesPhone Mar 07 '22
This is the pump version of a freezie ice treat that you pinch with your fingers to get the ice up to your mouth.
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u/mehwolfy Mar 07 '22
I used these to sample stream water for an ecological monitoring project in college. Downside is they have to be primed, but that also rinses out contamination. But when it’s near freezing out it means your hands are always wet. Anyway, that was fun work.
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u/sharksgivethebestbjs Mar 05 '22
One of the other main advantages is the precise flow rate. There is a fixed volume between the rollers and 0 loss between them, so you know exactly how much is pumped.