WaterWar.net

Hi!

I'm new to the forum here and (in full disclosure) not building a water blaster at all, but a drinkmaker the uses pressurized air to get liquids out of reservoirs. After a few frustrating trips to home depot wherein I failed to find the parts I needed, I began brainstorming communities of people with experience building custom pressure systems, and here I am. If anyone is willing to share his or her knowledge to my benefit, I'd be most grateful (and post videos of the project in action).

Below I've drawn a picture outlining the (current) problem. Basically, I'll have a pressure reservoir of liquid, a source of air pressure, and a spout by which the liquid exits. What's up in the air is:

1. What to make the reservoir out of? Ultimately, aesthetics will be a factor, though not for a prototype.
2. What types of fittings will allow for a good seal and easy of connection/disconnection for cleaning and whatnot.

Diagram below. Thanks in advance for any advice offered.

Brian

First of all, you might want to put the pressure tube on the top. It would be more practical and easier to build, although your current design would give it a cool bubble effect.

I once had a toy that worked just like this: Dr. Dreadful Demented Drink Lab. It included an electric pump connected to tubes, which could be connected to beakers to make the liquids go through them. It was cool, and I think it's originally what got me interested in stuff like this.

Anyway, I would use a 2 liter soda bottle for the reservoir. It's a safe, one piece container. For fittings, PVC would probably be best, but avoid using solvent since this is for drinks. When connecting everything together, slip them together without gluing them, or use threaded fittings. Use electrical tape on the outside if you have to.

It all depends on how much pressure you want to use. If you want a higher pressure system (to force more drink out of the reservoir in less time) then you'll need something stronger than if you use a relatively low pressure system. If the pressures you're talking about are anywhere below 100psi (but lets say 70psi to be safe), then go with m-shark's advice and use some form of fizzy drink bottle.

If I'm right in assuming you'll have a few of these reservoirs containing different types of drinks and only want to move the liquids to mix in another container, then you shouldn't need anthing near that sort of pressure, so yes a bottle that used to contain a fizzy drink will be perfect for a prototype (plus it lets people see how it works!).

The only problem with a plastic bottle is the limitations in the types of connections you can use. You probably won't be able to fit a connector into the side of the bottle without some form of adhesive. A better and cheaper bet, at least for a prototype, would be a snug fitting cork in the top of the bottle, with two small holes in it one for a pressure inlet, and one for the straw outlet). if you cut a small hole into the bottle cap, you can put this over the cork to stop the cork popping out. You could also find a way to connect directly to the bottle cap, but that would be a less easy option.

Something like this maybe:

Thanks for the brainstorming guys. I like the idea of a two-liter bottle with thin tubing providing pressure and fluid exit. Later, we may look for improved aesthetics (maybe glass, though that seems inherently risky in a pressure application) and higher flow with thicker lines that may not fit well in a two-liter neck. I'll post results once this thing is started.

Brian

Glass will stand pressure fine. 60 PSI in a glass bottle is nothing.

So the initial pressure is coming from an electronically controlled tire inflator capable of (roughly) 150 PSI. In doing this, I'd be making the assumption that the controls could fail and the glass receives the maximum physically possible pressure.

Downstream, we may use a tank+regulator setup. In that case, as long as you trust the regulator to function perfectly (or trust that nobody will tamper with it) you're fine. I would probably just want to be especially conservative because though the risk of failure is minute, the price is high.

I was thinking of using some type of mason jar, eventually. No idea what those can take pressurewise but with square corners I'd guess not enough for a conservative safety factor on the whole affair.

A glass bottle should be able to handle that sort of pressure mainly as it's thicker than plastic bottles. A plastic coke bottle can reach a maximum of 150-200psi before exploding (though I'd never want to test that with my face anywhere nearby). If you're worried about over-pressurisation, you could always use a pressure release valve with a release pressure of 60-ish psi. As far as tampering goes, as long as it's either not adjustable, or has a maximum pressure threshold which is less than your maximum safe working pressure, there shouldn't be a problem.

Obvoiusly if you do use a 2-litre bottle as the protoype, the tubing will be small due to the small neck of the bottle. On a larger scale you could use something with a large bung. You could always consider some chemistry equipment, such as a filtration flask (brand new of course, you don't know what chemicals have been in used chemistry flasks).

A large test tube might be possible too.

When I first saw this, I thought it said "drink make brainstorming better!" lol! I have slight dislescia so I mess up words some times (I also mess up spelling so bad even spell check can't help, hope you all can read that).

Not really one for building guns yet, I'm trying to master taking them apart and fixing them first. I am curios though, what are you going to use this for? For dispensing drinks wouldn't is be easier to just use one of those Rubbermaid drums with the spigot on the bottom?

Schedule 80 PVC. PVC solvent welding is safe for potable water, so I hardly see how it would be any worse in this application. Use 4" PVC and fittings for your reservoir (a bit pricey, especially with the SCH80 tubing, I'm afraid...) but the SCH80 is rated for far in excess of 150psi. Use a service cap for your lid (which gives a nice, flat surface to mount the outlet to) and use a 4" coupling with a built-in 1/2 or 3/4" saddle for your pressure line. Use a traditional cap for the bottom and build it a little base- for added redundancy, use a Dremel tool or the like to smooth out the stops in the coupling so your 4" PVC will slide all the way through, and jam it in there. Drill a hole in this inner layer to line up with the saddle, slap on your end caps, and you're good to go.

The service cap will require either 4 complete wraps with traditional Teflon tape (not! ideal!) or several wrappings with Teflon tape sold specifically for pressure applications. 4 wrappings of the little stuff was enough to stand up to my pressure test with my APH (125psi, held for ~1 hour) so either way you should be safe enough- especially if you have an active pressure source.

It could be easily painted/decorated for aesthetic purposes, as well. PVC is receptive to most paints as well as epoxy putties.

Edit: Additionally, if you use CO2 as your pressure source, bubbling it up from the middle will add a bit of "fizz" to the drink- especially if they are then stored under pressure.

scottthewaterwarrior wrote:When I first saw this, I thought it said "drink make brainstorming better!" lol! I have slight dislescia so I mess up words some times (I also mess up spelling so bad even spell check can't help, hope you all can read that).

Not really one for building guns yet, I'm trying to master taking them apart and fixing them first. I am curios though, what are you going to use this for? For dispensing drinks wouldn't is be easier to just use one of those Rubbermaid drums with the spigot on the bottom?

I haven't seen many of those used under pressure before, and wasn't sure how they'd do. I actually did buy one and remove the spigot before deciding it'd be easier to use two-liter bottles. Could be wrong though - these processes aren't always linear.

Jeffman3 wrote:Schedule 80 PVC. PVC solvent welding is safe for potable water, so I hardly see how it would be any worse in this application. Use 4" PVC and fittings for your reservoir (a bit pricey, especially with the SCH80 tubing, I'm afraid...) but the SCH80 is rated for far in excess of 150psi. Use a service cap for your lid (which gives a nice, flat surface to mount the outlet to) and use a 4" coupling with a built-in 1/2 or 3/4" saddle for your pressure line. Use a traditional cap for the bottom and build it a little base- for added redundancy, use a Dremel tool or the like to smooth out the stops in the coupling so your 4" PVC will slide all the way through, and jam it in there. Drill a hole in this inner layer to line up with the saddle, slap on your end caps, and you're good to go.

The service cap will require either 4 complete wraps with traditional Teflon tape (not! ideal!) or several wrappings with Teflon tape sold specifically for pressure applications. 4 wrappings of the little stuff was enough to stand up to my pressure test with my APH (125psi, held for ~1 hour) so either way you should be safe enough- especially if you have an active pressure source.

It could be easily painted/decorated for aesthetic purposes, as well. PVC is receptive to most paints as well as epoxy putties.

Edit: Additionally, if you use CO2 as your pressure source, bubbling it up from the middle will add a bit of "fizz" to the drink- especially if they are then stored under pressure.

Jeffman, that's probably the "pro-grade solution," but I may not be there yet. Thanks for the advice though, and for the heads up on the CO2. Right now I have an electric tire inflator rigged up, and will have to see how the drinks taste.

General Update:

I tried the "two tubes one cork" solution that Andrew was kind enough to post an image for above (04 May 2012). It works ok, but you've gotta be really light with the pressure or the cork blows out and scares the crap out of everyone. Capping seems out of the question, since with two tubes there's no way to screw the cap down, if that makes sense.

I'm starting to hatch a second plan, and that's to put some sort of T fitting through the bottle cap. One side of the T (outside the bottle) would be connected to gas. The other side (also outside the bottle) would be how the liquid exits. To let the liquid leave from the bottom of the 2-liter I'd snake a "straw" down through the T fitting and into the bottom of the bottle - the attached picture will help make more sense.

The big questions are:

1. How does one mount the T-fitting (which may need other pieces, flanges, etc) to the bottle robustly?
2. How does one seal the gap between the "straw" leaving the T fitting and the T fitting itself? Would it make sense to use a T-fitting with male threads in conjunction with a threaded end cap that I drill (and seal) a hole through?

http://www.fastfittings.com/brass-all-male-tee

braincof wrote:I haven't seen many of those used under pressure before

I think he meant without pressurising it (open the spigot and drink flows out).

braincof wrote:I tried the "two tubes one cork" solution that Andrew was kind enough to post an image for above (04 May 2012). It works ok, but you've gotta be really light with the pressure or the cork blows out and scares the crap out of everyone. Capping seems out of the question, since with two tubes there's no way to screw the cap down, if that makes sense.

Yes that will happen. My original suggestion was to:

cut a small hole into the bottle cap, you can put this over the cork to stop the cork popping out.

The hole in the top of the cap can be as large as necessary, as long as there is a small 'ledge' which can hold the cork into the neck of the bottle. From what you've already described, this should still be possible (using either a knife [take extra care] or a drill press).

I suggested this because of the few options for connecting to a 2 litre bottle (hence the additional suggestion of a filtration flask, with one of those special bung clip things to stop it flying out). If you really want to go for the T-junction, 22mm copper pipe fits perfectly within the neck of the bottle, and you could link a tee to this. The problem is then taste. You may not find the slight coppery taste too pleasant. The other option is to fix the tee to the cap with adhesive (but you will have to find non toxic adhesive obviously).

EDIT: You might be able to connect a tee to a threaded adaptor (male) and use a nut on the inside of the bottle cap. Due to the size of the cap, you'll be looking for around 1/4" threaded connectors and nuts. A washer should seal it if the inside of the cap is smooth.

@Andrew:

Thanks for all of the helpful hints, and good to know that 22mm fits perfectly. I'll try boring out the cap and see how far that takes me.

No problem! I want to see this thing working nearly as much as you do!

braincof wrote:I'll try boring out the cap and see how far that takes me.

If that doesn't go well, you could make a rubber 'boot' out of something and clip it to the cork and bottle neck with jubilee clips to hold it in (probably won't work as well as if you can get the bored cap to work though). if you do make a mistake, it's not like you can't replace the bottle cap.

That's the current setup, actually - rubber boot hose clamped (as they're known this side of the pond) over the neck of a tequila bottle. No pressure in that setup, though, just gravity feeding.

It also raises an interesting question: given the low-cost and widespread availability of 2 liter bottles (and hence their use by pressure hobbyists) why hasn't someone produced a screw-on pressure fitting for those bottles? Seems like there's a market.

You could always modify one of these, or modify a carbonator (remove the ball seal thing). They are used by home brewers with compressed gas so they are pressure rated too!

One other thing, I'm guessing that (in your drawing) the inside of the tee looks something like this:


If it doesn't it won't work as well as compressed air will just go straight out through the exit tube.

A possibility would be to get a 3/4 in female threaded tee, which will somewhat screw on to the bottle (can be inproved with some sort of glue), and then use a hose barb in conjunction with large and small vinyl tubing, putting the one on the outside of the hose barb, flowing towards your tap or whatever, and the smaller one inside the barb- might be difficult to find the right fit) and headed into the bottle.

Also, your most recent design will not have any purty bubbleses.