Food grade liquid 'pump' (alternative?)

Projects General Guidance
1

Hey gang-

I am (slowly) working on making a BarBat (YouTube it.. there are TONS out there)..

What it is.. is basically an automated drink maker using stepper motors and a linear rail system..

The liquor bottles are held upside down, and use measured optics to provide the alcohol part..

For the 'mixer' liquids (soda, orange juice, cran juice..etc).. I was initially looking into peristaltic pumps..

what I didnt know/realize was that they dispense the liquid in little 'bursts'... totally not acceptable when you need to fill the rest of the glass with OJ.. but you have to wait for it to fill up 'drizzle/burst' at a time.

I need more a constant 'flow' (if that make sense?)

This project is my 'goal'... (really like this one)

If you look to the left.. there are just a bunch of 'hoses' that dispense the 'mixer' liquid into the cup at a nice/fast rate.. filling it up quickly.

I'm having a hard time trying to understand how they set this up however? (without pics, my mind wonders!)

On their site, they state the following:

"All mixers are in plastic bottles in a cool box, each bottle has two pipes, one that is hooked to the gas tank (70% Nitrogen and 30% Carbon Dioxide), and the other goes from the bottom of the bottle to a valve. When the gas tank is opened (through a regulator) the bottles are pressurised to a low safe pressure. When 12v is applied to the valve it opens, and the pressure causes the liquid to flow through the pipe and ultimately into the glass. Each mixer has its own valve and individually controllable. There is also a cut off valve for the gas supply."

So to regurgitate this into more laymen/noob speak..

  • All mixers are in their own 'bottles' (in a cool box? refrigerator perhaps?)

  • these bottles have two hoses connected to a 'gas tank'? (is this a single gas tank containing, 70% Nitrogen and 30% CO2?.. or separate gas tanks?)

  • pressurized at a safe pressure (which is what? does that mean you turn on the tank.. 'pressurize' the bottle/contents... then turn the tank off? Or is this a constant on 'level'?.. once its down.. you dont have to do it again? or at least until you see/feel the mixer fluids not coming out as fast/at all...etc)

  • Apply 12v and the 'valves' open (what values? are these specific to food grade ones?)

From this picture.. it 'looks' as if the values used are these:
Pic: (far right side,..follow the tubes and placement from the video above)

Value:

Which works for me! The price is 'acceptable'... especially when I'll have like 6-8 mixers!

What I need is some 'chit-chat' to help my understand the gas-tank approach they are doing for the pressurizing the mixer liquids.

Are these 'tanks' expensive? Where do you get a mix of Nitro and CO2?

Thanks for helping me plan out my project! (All feedback appreciated)

2

look for welding supply company in your area. They can point you to the source of the gas if they can't supply it.

Paul

3

xl97:

  • these bottles have two hoses connected to a 'gas tank'? (is this a single gas tank containing, 70% Nitrogen and 30% CO2?.. or separate gas tanks?)

You can get tanks with the blend. Called "beer gas" or "draught gas" because it's used for carbonating and dispensing draught beer on tap. You can also use separate CO2 and N2 tanks to create custom blends specific to the type of beer. For soda fountains only CO2 is used. These tanks should be readily available pretty much anywhere since this is a very common thing. In your case since you're only trying to dispense and not carbonate I don't think it will matter whether you use CO2, CO2/N2 blend or just N2.

I wonder if you could even use a low pressure membrane air pump instead. The downside to that is the noise. It might be nice not to have to deal with the tanks but they should be cheap and one tank of gas would probably will last a long time.

xl97:

  • pressurized at a safe pressure (which is what?

It depends on the container. You definitely need to be careful not to exceed what the container can handle. I don't think it will really require much pressure to push the liquid through the hose. I saw one barbot with this pressure dispensing system that used plastic soda bottles. Those are actually made to handle some pressure (since they store carbonated soda), are food safe, and readily available. Unlike glass, if one did burst you wouldn't have dangerous shrapnel flying around, but only a mess and lost liquor.

xl97:
does that mean you turn on the tank.. 'pressurize' the bottle/contents... then turn the tank off? Or is this a constant on 'level'?.. once its down.. you dont have to do it again? or at least until you see/feel the mixer fluids not coming out as fast/at all...etc)

It will be best to leave the tank constantly open to the containers. You will have a regulator that maintains a specific pressure in the containers.

xl97:

  • Apply 12v and the 'valves' open (what values? are these specific to food grade ones?)

"valve", not "value". It's definitely a good idea to get food grade valves since you don't want your drinks to be contaminated.

4

oh.. LOL.. so this isnt a special kind of tank?

(I just filled up the tank for my welder too!) LOL

Its literally a big metal 'tank'...

How much do you think its needed? I'd like the keep the extra/external components to a minimum, and to a size that helps keeping things mobile.

As far as the bottles that holder the mixer liquid..... do they need to be anything special? as to hold the pressure? or will regular 2 liter bottles work?

5

Just really quick!

@pert

Thanks for the reply... I on my out of work.. and will read your post more in depth tonight!

Thanks!

6

When it comes to dosing liquids, persistaltic pumps are definitely the most accurate and easy to control (just pump for some amount of time). The fastest I have do about 80 ml/min, and that are pretty small pumps. Get bigger ones with bigger hoses and you'll definitely get bigger flow out of them. A few seconds per ingredient should be acceptable, no? Indeed the flow is not perfectly constant but does that really matter so much?

Another option is indeed to pressurise your containers and use a small solenoid, open it for a specific time. That should give a quite accurate volume as well. You can pressurise PET bottles to a certain extent, just make sure you don't exceed the safe limit for those bottle (I really don't know what that limit is - at least you should use thick walled coke bottles, not the flimsy water bottles).

CO2 gas should indeed be easy to find with a catering supplier. Alternatively use a small air compressor.

7

"It will be best to leave the tank constantly open to the containers. You will have a regulator that maintains a specific pressure in the containers."

I was just coming back to comment on this.. and see you already touched on it.

I was thinking...........over time.. the 'mixer' dispenser pressure (not the liquor that uses the measures optics)... will not be equal?

If I open the tank up.. 'pressurize' the mixer bottles.... after the first drink in made/mixer fluid is dispensed.. the 'pressure' will now be lower...

each consecutive time a drink is made.. the pressure will be less and less.. making the drinks un-equal....no?

if I have a value set to be open for say 2 seconds (or whatever).. that same '2-second' threshold will dispense/delivery less fluid each time.....correct?

This must be where this 'regulator' you mention comes into play here?

So your solution that problem is use a regulator... and keep the tank on (open) at all times? (when in use)

I think I am going to try this approach first.

to re-cap:

  • tank to hold nitrogen/CO2
  • regulator for said tank
  • mixer bottle 'holders' capable of being pressurized - (are there pre-made containers for this? instead of trying to use a 2-liter.. where I feel the failure point might be where the lines have to be added from a DIY process)
  • food grade values ( x however many mixers I have)
  • 2 x lines per mixer bottle (1 x pressure/gas input 1 x mixer liquid output) - do these lines need to be anything special? Do they too need to be able to hold a specific amount of pressure?

I was planning on using this for the linear rail system

Its a nice and complete packages... but jumps the price right up to around $120 or so.. without shipping already!

The only negative I see with the above (which is just a preference really) is that the stepper and idle pulley are on the ends.. make it wider over all..but not more travel.

I'd like to find a nice belt & pinion type of approach so I can have the stepper motor MOVE along with the cup holder platform
(as well as have all other electronics in side the cup holder 'box')

Anyone know of a complete kit like the above.. but with a belt & pinion set-up per chance? (and cheaper?) LOL

I dont need it to be a v-slot either.. actual round bar/rails is fine too.. (just looking for a complete set-up as well as belt & pinion or even rack and pinion I suppose)

Think a small tank like this should work?

(although I like the red one better...LOL)

I also found 1 that is just slightly over 1lb:
https://www.ebay.com/itm/20oz-CO2-Tank-Aluminum-Draft-Beer-Kegerator-Homebrew-Welding-Aquarium-Hose/151292432978?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D52475%26meid%3Df066ec3ef560426384d15e341150f0bc%26pid%3D100005%26rk%3D3%26rkt%3D11%26sd%3D151292426970%26itm%3D151292432978&_trksid=p2047675.c100005.m1851

for roughly same price as the 5lb one though! :frowning:

Not sure if it has any advantages or not.

Still need to find a cheap gauge as well...

8

It's normal to use such cylinders with a regulator. High pressure (for CO2 60-80 bar or so; other gases can go way higher) to a more manageable pressure on the outlet. That pressure you use for your bottles, so when liquid is drained, gas is automatically filled and pressure remains the same.

9

xl97:

  • mixer bottle 'holders' capable of being pressurized - (are there pre-made containers for this? instead of trying to use a 2-liter.. where I feel the failure point might be where the lines have to be added from a DIY process)

I agree that could be tricky. The one I saw they drilled holes in the stock bottle cap and then glued the two tubes in. That means you would need to find a glue that it compatible with the plastic of the cap and the tubing material and is strong enough to handle the pressure. It would be great to have something with hose barb nipple connectors you could just slip your hoses over and put a hose clamp on them. Remember that the outlet hose needs to go inside the bottle to the bottom so that's even more tricky!

xl97:

  • 2 x lines per mixer bottle (1 x pressure/gas input 1 x mixer liquid output) - do these lines need to be anything special?

I'd go for food safe, especially for the output tube.

xl97:
Do they too need to be able to hold a specific amount of pressure?

Yes. At least whatever the tank regulator is set to. I think the standard regulators you'd get for beverage gas tanks would be a higher pressure than is necessary since you are not wanting to carbonate. You only need enough pressure to push the liquid through the system. How much pressure that is would probably need to be experimentally determined.

xl97:
Its a nice and complete packages... but jumps the price right up to around $120 or so.. without shipping already!

With 3D printers being so common these days, it seems like you should be able to find a better price. It's not as if you need sub-millimeter precision so even the cheapest should be plenty fine.

xl97:
for roughly same price as the 5lb one though! :frowning:

Not sure if it has any advantages or not.

You'll need to get the small bottle filled more frequently than the large one.

10

every soda joint you see has CO2 under pressure that mixes with the beverage, so CO2 tanks and valves and regulators should be quite common.

considder that 1 inch of water would lift the fluid up 1 inch. OK, so it is not rocket surgery.....
so, 1 PSI would lift up your fluid 27.7 inches of water. makes a regulated line pressure of 1 PSI to seem very high.

second : with 1 psi and a 5/16 diameter inside of pipe, one can calculate the volume per second.

ergo, all you need to do is to invite a whole bunch of friends over, get some Stoli and some O.J. and play that "is this drink too strong?" game.

you should be able to hone in to 1.00 ounces per X time at X PSI in short order.

11

pert:
the outlet hose needs to go inside the bottle to the bottom so that's even more tricky!

Not more tricky at all, just use a long enough hose so it reaches the bottom.

12

wvmarle:
Not more tricky at all, just use a long enough hose so it reaches the bottom.

Wow really, genius! I would have never thought of using a long enough hose.

13

It the first video, it looks like they use a simple bar bottle with a bar bottle pour cap. the device has two openings, one for air, one for the liquid. the air is only an inch longer
this is set into a shot-glass. the size of the shot glass and the diameter determine the volume and depth of the pour cap determine the exact amount of fill. no pressured air needed. the weight of the liquid is enough to dispense.
the solenoid is connected to a drain line under the shot glass.
I assume the shot glass assembly is cleanable/removable.
I would also assume there is a second solenoid or servo, to cap off the liguid and air hole when the unit is not being used.

My thoughts go to a teeter-totter valve mechanism.
in the un-used state, the spring or weight would cap the air and liquid holes.
when activated, it would open them and allow the liquid to pour.
when activated, the shot glass hole would be plugged and the glass would fill.
possibly to a sight line, or liquid sensor
when the unit is de-activated, the bottle is capped, and the shot glass is drained.

that way, the only time air gets into the fluid is during the pour cycle.

being on a lever or plunger means only one coil needed.

if you ever saw a soda machine that has a wrist weight, you lift the weight, the pincher relaxes the tube and the liquid flows.