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Author Topic: Peristaltic pump (flow rate ~1000ml/min) or better solution?  (Read 1057 times)
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Hi,

I'm new both here and to electronics. Halfway through Make: Electronics and already hooked smiley

I'm looking for a peristaltic pump with a flow rate of about 1000ml/min to pour shots with.

I've only found 100ml/min on eBay. Anyone know where I can find what I'm looking for at a decent price?

Or am I looking for the wrong part? Maybe there is a better way to pour shots?

Appreciate any help!

Thanks in advance!
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The thing about peristaltic pumps is that they are used for precise metering of fluids - generally in a medical setting; for most uses, 1 liter/second is way too high. You likely won't find such a pump because there isn't a need for it in the niche those pumps are used; if you insist on such a pump, you'll either have to custom build it, or if you find such a pump, it's going to be fairly expensive.

There are three basic systems typically used for "automated bar" pouring - all will require an alternative method to meter the fluids:

1) Gravity feed
2) Pressurized system (generally via CO2 or nitrogen)
3) Windshield washer pumps

Note that if you go with #2 - you -will- want to use CO2 or nitrogen; using plain air can work, but it isn't generally considered "food safe" (which is why the beverage industry uses those gases in fountain drink machines). Be sure to purchase food-grade CO2 or nitrogen, and to use food-grade parts and lubricants, because industrial grade gases can have contaminants as well as machine oils in them, and the tanks (which you rent, generally) may have been used in a situation in which contaminants could have gotten inside the tank (perhaps the last renter opened the tank, and "cleaned" it, then put some other gas inside or something - who knows!).

Ultimately you'll want to make sure all of your parts that come into contact with the food liquids not only are impervious to ethanol, but are also food-grade or certified for food usage (especially if this is for a commercial setting or product - for a home based system, you can do what you want, as long as you and others using the machines realize the long-term potential risks).

Metering the product will be the difficult part; you could use a scale of some sort (or a similar weight/mass sensor), or you could look into an appropriate flow meter to insert into the output line (again, make sure it is a food-grade part and can be used in the presence of ethanol). Generally, though, a little variation in a mixed drink is not that big of a deal; most of the time, a bartender is not going to whip out a graduated cylinder or something to measure out each and every drink or shot. It gives it a bit of character in the difference, IMHO. So - simply doing a weight/volume measure should be fine. Even just timing the output may be enough (though that wouldn't catch an empty bottle/reservoir)...
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The thing about peristaltic pumps is that they are used for precise metering of fluids - generally in a medical setting; for most uses, 1 liter/second is way too high. You likely won't find such a pump because there isn't a need for it in the niche those pumps are used; if you insist on such a pump, you'll either have to custom build it, or if you find such a pump, it's going to be fairly expensive.

There are three basic systems typically used for "automated bar" pouring - all will require an alternative method to meter the fluids:

1) Gravity feed
2) Pressurized system (generally via CO2 or nitrogen)
3) Windshield washer pumps

Note that if you go with #2 - you -will- want to use CO2 or nitrogen; using plain air can work, but it isn't generally considered "food safe" (which is why the beverage industry uses those gases in fountain drink machines). Be sure to purchase food-grade CO2 or nitrogen, and to use food-grade parts and lubricants, because industrial grade gases can have contaminants as well as machine oils in them, and the tanks (which you rent, generally) may have been used in a situation in which contaminants could have gotten inside the tank (perhaps the last renter opened the tank, and "cleaned" it, then put some other gas inside or something - who knows!).

Ultimately you'll want to make sure all of your parts that come into contact with the food liquids not only are impervious to ethanol, but are also food-grade or certified for food usage (especially if this is for a commercial setting or product - for a home based system, you can do what you want, as long as you and others using the machines realize the long-term potential risks).

Metering the product will be the difficult part; you could use a scale of some sort (or a similar weight/mass sensor), or you could look into an appropriate flow meter to insert into the output line (again, make sure it is a food-grade part and can be used in the presence of ethanol). Generally, though, a little variation in a mixed drink is not that big of a deal; most of the time, a bartender is not going to whip out a graduated cylinder or something to measure out each and every drink or shot. It gives it a bit of character in the difference, IMHO. So - simply doing a weight/volume measure should be fine. Even just timing the output may be enough (though that wouldn't catch an empty bottle/reservoir)...

Thank you very much for your response!

Considering what you wrote, I've changed my strategy to load sensors for determining the output volume. That gives a bonus of auto pouring the shot when a glass is put on the sensor.

Ordered two of these today: http://www.ebay.com/itm/360740315934

What I do need though is to start the pouring somehow. I was thinking placing the bottle up side down, but I still need a ball valve hooked up to a servo or something to start and stop the flow. Any ideas?

Maybe something like this and hook up a servo to it? http://www.ebay.com/itm/Rotating-4-Bottle-1-1-2-Ounce-Drink-Dispenser-bartender-shot-party-carousel-/230877773364
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Try some of these small pumps, one rotation of the axle = finite, measurable amount.   
micro rotary wheel pump
http://www.welco.net/

Hook up the pump to either a stepper motor or a continuous servo (call the company for the torque reqirements)

Or you can use a Misty mate hooked up to a solenoid valve, you time the valve to get a ms/ml value, you can add a micro pressure regulator so the bottle has a constant air pressure and thereby constant flow.   

Misty Mate
http://www.campingworld.com/shopping/item/Misty-Mate-16-Classic/60120/&?&affiliateid=3274&cvsfa=2734&cvsfe=2&cvsfhu=3630313230&gclid=CJeC4caM8rkCFYs1QgoduiMA6A

Pressure regulator
Mcmaster.com part no 3834T51   $16.02

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What I do need though is to start the pouring somehow. I was thinking placing the bottle up side down, but I still need a ball valve hooked up to a servo or something to start and stop the flow. Any ideas?

You might looking into small plastic ball-valves or needle valves at a hardware store - you'll want to stay away from anything metal, though (corrosion issues, mainly).

If you can engineer a method to hook the bottles up (upside down) to a sealed interface with two tubes/holes, with one tube extending into the bottle to the airspace at the top - then you could simply "pour" from the tube/hole under the liquid by blocking and unblocking the other tube to let in air (you can't just turn a bottle upside down without a way for air to enter to displace the fluid pouring out).

Alternatively, if you go with re-fillable bottles of some sort, you could drill a hole at the "top" to allow air in, and then either cover/uncover the hole with a valve of some sort, or use the ball valve or other method on the output tube.


Perhaps - it would all depend on how easy it would be to mechanically couple the servos or whatnot to the mechanism that operates the valves on the bottles. You might see if you can check one out "in person" before purchasing one online (heck, I've seen these dispensers on and off being sold a Goodwill cheaply).
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