Liquid flow control

[sgpope]

I'm trying to figure out how to control the flow of liquid from a bottle (2 liter bottle maximum). I've already picked up some solenoids (from seeedstudio Electric Solenoid Valve [SWT133B2B] - $8.50 : Seeed Studio Bazaar, Boost ideas, extend the reach), only to discover that the pressure of the water isn't enough to get through the opened solenoid.

I'm thinking of two possibilities now:

- Add pressure. Not sure how to accomplish that.
- Change tactics. Possibly using a servo to tilt the bottle down and up. I've never used a servo yet, so I don't know how exactly to hook it to a bottle, which size servo to get, or any of that.

Any better ideas?

 

[KMoffett]

How about a big-picture description of what you are trying to accomplish. And things like head (height), flow rates...?

Sometimes it's easier for us to help solve your problem, than help solve your solution..

Ken

Oh, and splitting out on a new thread on the same project can just be confusing to posters.

 

[sgpope]

Sure thing. I'm trying to figure out how to build a bar-bot. It will have 6 containers of liquid, and be able to accept input from software on a connected laptop to dispense the liquids in the proper amounts (which will be between 0.1 oz and 16 oz). I've tried some experiments using the solenoids I mentioned earlier, only to discover that there's not enough pressure from the 2L bottle to push through the opened solenoid.

 

[blueroomelectronics]

Put the upside down bottles up higher and someway to allow air into the bottle.

 

[Mosaic]

I don't suppose u thought about an air bleed hole in the base of the upside down bottles?
Or ...place an air pressure nipple on the base of the bottles and use an aquarium pump on it.

 

[KMoffett]

Unless you can maintain fixed pressure differentials between the supply bottle and the outlet point, I don't think you can use a timed-solenoid control with those volumes. Peristaltic pumps would be a better much choice. Also, since your are dealing with consumable liquids you need to assure that all of the materials in your system are food-safe, and compatible with alcohol and other ingredients of the liquids. Is this for commercial or personal use?

Ken

 

[MrAl]

Hello,

It seems to me that if you have a small tube in the lower part of the bottle and the upper part of the bottle is completely closed, nothing will flow out the lower tube. The upper part of the bottle would have to have an air vent to allow air to enter the bottle from the top.
There is a problem in doing it this way however and that is that a container with a hole in the bottom does not meter out water at the same rate all the time if the container is being emptied. That's because the pressure changes as the liquid level decreases. That means it may be hard to meter out the correct amount.
To make up for this error you can note that it is very systematic and thus predictable. You'd only have to do a few tests to determine how to vary the 'open' time period having the previous history stored in memory, and have the system reset every time the bottle is refilled, however you'd have to refill it to the same level each time. That assumes you dont want to be bothered with measuring the liquid level either.

Also, by opening the upper tube to allow air to enter the bottle that's when the flow would start not using a solenoid valve unless the lower tube diameter was large. That means it might even be possible to use a very small solenoid air valve rather than a valve that has to come into contact with the liquid constantly.

 

[sgpope]

I don't suppose u thought about an air bleed hole in the base of the upside down bottles?
Or ...place an air pressure nipple on the base of the bottles and use an aquarium pump on it.

I tried poking a hole in the bottom of a bottle to test, but it still wasn't enough pressure to get through the solenoid.

 

[sgpope]

Unless you can maintain fixed pressure differentials between the supply bottle and the outlet point, I don't think you can use a timed-solenoid control with those volumes. Peristaltic pumps would be a better much choice. Also, since your are dealing with consumable liquids you need to assure that all of the materials in your system are food-safe, and compatible with alcohol and other ingredients of the liquids. Is this for commercial or personal use?

Ken

Some good considerations here. Know where I can get some cheap peristaltic pumps? This is for personal use. I'd never subject anybody else to one of my creations.

 

[sgpope]

Hello,

It seems to me that if you have a small tube in the lower part of the bottle and the upper part of the bottle is completely closed, nothing will flow out the lower tube. The upper part of the bottle would have to have an air vent to allow air to enter the bottle from the top.
There is a problem in doing it this way however and that is that a container with a hole in the bottom does not meter out water at the same rate all the time if the container is being emptied. That's because the pressure changes as the liquid level decreases. That means it may be hard to meter out the correct amount.
To make up for this error you can note that it is very systematic and thus predictable. You'd only have to do a few tests to determine how to vary the 'open' time period having the previous history stored in memory, and have the system reset every time the bottle is refilled, however you'd have to refill it to the same level each time. That assumes you dont want to be bothered with measuring the liquid level either.

Also, by opening the upper tube to allow air to enter the bottle that's when the flow would start not using a solenoid valve unless the lower tube diameter was large. That means it might even be possible to use a very small solenoid air valve rather than a valve that has to come into contact with the liquid constantly.

I like this idea too. I've got some free-pour spouts that I can use to control the flow more precisely (once I get a good flow going, of course), so I'm not as worried about having to calculate the flow rate. Presumably I'd have to configure it to ignore the first few seconds of flow from each bottle to give it time for the liquid to get to the end of a hose or something.

 

[KMoffett]

Some good considerations here. Know where I can get some cheap peristaltic pumps? This is for personal use. I'd never subject anybody else to one of my creations.

Cheap peristaltic pumps?...No! An alternative would be to have stoppers in each bottle with two ports...one outlet for the liquid and one inlet for a constant low-pressure air supply. All the bottles would be connected to the same air supply. This would allow a fairly constant flow rate with the timed solenoid arrangement.

Ken

 

[sgpope]

Cheap peristaltic pumps?...No! An alternative would be to have stoppers in each bottle with two ports...one outlet for the liquid and one inlet for a constant low-pressure air supply. All the bottles would be connected to the same air supply. This would allow a fairly constant flow rate with the timed solenoid arrangement.

Ok, so I'm picturing something like a cork (of sorts) with two hoses going out of it. One of the hoses connected to an aquarium air pump and the other going out to the solenoid. Is that about right? If that's what you're thinking, do you know where I can get a cork that'll fit several bottle sizes?

 

[KMoffett]

That's the concept! Lots of stopper suppliers. Googled: rubber stoppers 2 hole

Search Results

**broken link removed**

Single Stoppers 2 Hole: The Science Fair Inc.

Ken

 

[SABorn]

Have you been to a night club and ordered a spirit drink and taken note to the dispenser system they often use.

The ones that come to mind are dispensers that the glass is pressed up under the inverted bottle, and the spirit then flows a measured dose into the glass and shuts off, after the glass is removed it then allows air into the bottle as it refills the measure chamber again ready for the next glass.

Maybe you could use a similar system with a small motor with a cam on the shaft to replace the glass action of activating the flow.
Home bar dispenser systems are available and might be easier to retrofit for the application than solenoids and timers etc.

Also you have the advantage of knowing the device is made for food products and safe for use with alcohol

Link here to product example.

**broken link removed**

 

[sgpope]

Have you been to a night club and ordered a spirit drink and taken note to the dispenser system they often use.

The ones that come to mind are dispensers that the glass is pressed up under the inverted bottle, and the spirit then flows a measured dose into the glass and shuts off, after the glass is removed it then allows air into the bottle as it refills the measure chamber again ready for the next glass.

Maybe you could use a similar system with a small motor with a cam on the shaft to replace the glass action of activating the flow.
Home bar dispenser systems are available and might be easier to retrofit for the application than solenoids and timers etc.

Also you have the advantage of knowing the device is made for food products and safe for use with alcohol

Link here to product example.

**broken link removed**

Lots of advantages, but a big disadvantage. I want to be able to measure in amounts between 0.1 oz (a splash, basically) and 16 oz.

 

[Reloadron]

Have you given any thought to a volumetric system? For example when I load rifle ammunition for general use I use a volumetric setup for my powder dispensing. The same concept can be applied to liquids.

Ron

 

[sgpope]

Have you given any thought to a volumetric system? For example when I load rifle ammunition for general use I use a volumetric setup for my powder dispensing. The same concept can be applied to liquids.

Ron

Sorry, I've no idea what a volumetric system is. Could you explain a little about how it works?

 

[Reloadron]

Sorry, I've no idea what a volumetric system is. Could you explain a little about how it works?

Volumetric just means if I want to dispense a given amount of something (could be liquid or a powder solid) we can fill a cylinder that is adjusted to hold a given volume. For example we have a supply or a hopper, the supply fills the cylinder, then the cylinder is emptied.

The problem with dispensing liquids is sometimes difficult because of outside factors. Water is easy because it doesn't change much but other liquids can change like for example heavy syrups.

There are other ways to dispense a liquid but they get more complex (though accurate) and increase the cost.

Ron

 

[SABorn]

You do realize you can get solenoids that will open and allow gravity flow through them.

Most solenoids work on a diaphragm that pressure opens when a small bleed off is opened via the coil, this allows for a difference in pressure across the diaphragm so it can open....No good for your application

There is solenoides that are made for gas and air flow that will open the port via the coil.
I have used these before for low gravity flow of liquids, and the ones i used was sold for LPG gas systems in cars and had a brass body, but have seen others that have a plastic body.

When the coil of these are energized you can blow air easy in both directions through the solenoid with your mouth.
Most times these valves have a 1/8 NPT thread in the body.

I had used these solenoides in a liquid additive system for hydroponic nutrient and it worked very well, which is similar to what you want to do.

Pete.

 

[sgpope]

You do realize you can get solenoids that will open and allow gravity flow through them.

Most solenoids work on a diaphragm that pressure opens when a small bleed off is opened via the coil, this allows for a difference in pressure across the diaphragm so it can open....No good for your application

There is solenoides that are made for gas and air flow that will open the port via the coil.
I have used these before for low gravity flow of liquids, and the ones i used was sold for LPG gas systems in cars and had a brass body, but have seen others that have a plastic body.

When the coil of these are energized you can blow air easy in both directions through the solenoid with your mouth.
Most times these valves have a 1/8 NPT thread in the body.

I had used these solenoides in a liquid additive system for hydroponic nutrient and it worked very well, which is similar to what you want to do.

Pete.

I realize there are solenoids that suit my purpose better. But the ones I've got I've already got.