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Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Mon May 26, 2014 1:22 pm
by neb777
So I have an idea to use the 100oz/4500psi HPA (High pressure air) tank from my paintball gun to power a watergun.
I am seeking any advice / criticism. see image for details.

pic attached is based on the tanks i already have. but i was also thinking of welding a third fitting to the bottom of the reservoir tank and connecting the water out there to avoid the need of the internal rod as it's removable if i change the fitting at the top to just a ball valve for filling.
glitchwatergun.jpg (124.75 KiB) Viewed 2348 times
anyone else build anything like this?
been trying to find others who have tried and the closest i could find is this: ... oaker.html
but there are no performance details... duration... distance... w

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Mon May 26, 2014 3:12 pm
I've thought of the idea a few times, but given how much money I'm already spending on things that don't quite work, I'm not about to plunk down more cash for more things that may not work.

Here are a few things:
- It's good that you're using HPA instead of CO2 for safety reasons.
- Both your design and the UberSoaker don't have ideal flow due to the valves used, although at higher pressure that may not matter especially if you have a laminator.
- If you're using a backpack setup, I recommend more water for the tank than 100 oz. You're going to need a lot of water at high flow rates.
- I recommend against using an intake tube as depicted. This causes major performance issues and prevents all the water from emptying out as easily. Simply having the hose on the bottom instead makes it easier to build and use, and gives better performance. If you can weld something to the bottom of the tank, that would be ideal. However, I'm not sure on the best way to do this; you'll almost certainly need special tools anyway. If the tank you're using is designed for air, rust may also be a concern.

For optimum performance, the best setup is to connect the hose directly to a ball valve, and the ball valve directly to a nozzle. The SuperCAP features this setup, with a handle added in using a drainage tee/outlet [McMaster part# 4880K107, with a few other sizes available]. This will give optimum stream performance. (Although I also recommend a conical nozzle to go with that.)

Anyway, someday, I may build something like this, should I decide to dispose of additional income. I've been meaning to get into paintball in general, but haven't managed it yet.

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Mon May 26, 2014 5:45 pm
by martianshark
I've wanted to build a similar homemade for a long time.

Using a paintball canister is a pretty neat idea. I'm not sure about using a solenoid valve for the trigger valve. It may reduce flow, and with the way you have it set up, water will dribble out the end of the gun, causing lag when you fire. You might be able to solve that by putting a check valve in front of the nozzle, but this again would reduce flow significantly. A brass ball valve would be cheaper and easier, but it would require two hands to operate, unless you can build your own trigger mechanism.

45 PSI isn't very much. I believe that's about what the Super Soaker 50 operated on. In my opinion, 120 PSI would be great. Maybe a little less. Be sure of course to use pressure-rated tubings and fittings.

As CA99 said, an intake tube probably isn't the best idea. I would recommend flipping the reservoir upside down and connecting the tubing there. And you should carry more then 100oz.

Out of curiosity, what is the safety issue with CO2?

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Mon May 26, 2014 6:12 pm
^ Yeah, I forgot to mention, using a "barrel" as a nozzle is a bad idea in general. It's a topic that's been well discussed previously. Here are a few links.

Check the pressure ratings of all components you use, not just whether they are rated. Ensure all connections are done properly too, and it should be good.

CO2 tanks lack some mechanism of pressure relief. That means overfilling them can have deadly results. In addition, I've read reports/posts where people have had faulty CO2 tanks, but cannot de-pressurize them nor remove them from their equipment. (Attempting to remove would turn it into a deadly projectile.) Both CO2 and HPA can be dangerous if there's any damage along the tank or nearby (i.e. from long term metal rust, or dropping it on hard surfaces, etc.), although they are very likely to be far safer than PVC douchenators/WBL's since that kind of equipment was actually designed for that specific application. Your best bet is a carbon fiber HPA tank, which is lighter and stronger than metal tanks.

Although you don't want to test the PRV on an HPA tank, it's still much better to have one especially considering the fact that this stuff is running at thousands of PSI.

In addition, CO2 can be a temperature hazard. It can chill the water to well below freezing, without the water actually freezing due to the pressure (and/or other effects; I'm not a chemist/physicist), which could be dangerous to blast at others.

Perhaps my suspicions of CO2's safety are being blown out of proportion, but with something that lacks a PRV and has the "deadly paintball air tank shooting off" reputation, I don't want to mess with it.

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Fri May 30, 2014 8:19 am
by neb777
Thanks CA99 thanks for the advice and those links made for some good reading.
and Martianshark... you may be right about the PSI but i'll have it adjustable as the reservoir can take up 250PSI

I've decided to take out the intake tube for performance reasons... it should come out of the tank pretty easy... haven't decided if I'm gonna flip the tank or weld another threaded valve to the bottom yet.

now contrary to most people i'm not aiming for high volume or distance...
i want about 20 feet... and ideal a fine steam breakup so it more of a spray than a squirt...
sprays will last 2 to 7 seconds at a time... the reason it is gonna work off an electric solenoid is it'll be attached to a motion sensor trigger... and pointed at my back patio where the neighbors cat keep peeing on my door mat because it wants to bang our cat and somehow think the peeing on my back door is gonna win him some point with out cat...

that said... unscrewing everything after the res tank and replacing it with a hose with a ball valve will make a pretty mean watergun too so really it's a multi purpose system I'm trying to make here...

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Fri May 30, 2014 1:42 pm
by isoaker
Flipping the tank sounds like the simplest solution if you can mount it in such as way not to crush/pinch the tubing. That way, you wouldn't need to cut/weld anything that may compromise the stability of the tank. If you're not going for much range or output, somehow 200 PSI (or even 100PSI) seems like overkill for your needs. :goofy:

Of course, there are also these type of things available and this other stuff, too, but building things is half-the-fun.


Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Fri May 30, 2014 4:50 pm
by martianshark
If you're not using this for water fights, then there are a lot of things you don't have to worry about. A solenoid will definitely be fine for your purposes, but try to put it as close to the nozzle as possible. Somewhere around 45 psi should be fine, and it doesn't really matter that much if you use an intake tube or not. And 100oz will most likely do the job, although if you can, there isn't really a reason to not give it bigger capacity. Also, I would recommend attaching a nozzle with a wide spray and setting next to your patio. Otherwise, the cat may figure out how to dodge it easily.

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Fri May 30, 2014 6:54 pm
If you're just trying to shoo cats, just get a WW Python 2.

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Sat May 31, 2014 12:22 am
by martianshark
Python 2 can't be automatically activated though. But honestly, a modified Thunderstorm attached to a motion sensor would probably do the trick should you give up on this idea.

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Sun Jun 01, 2014 11:34 am
by neb777
ISOAKER: Yeah i know those are available... but as you said building it IS half the fun...

Martinashark: Well... this will be it's primary home... i cant have water fights all the time... but i want to build in such a way that it can be easily switched over for a high power water fight... IE: have a good base setup where all i need to change is say the nozzle as maybe a larger reservoir... easy enough

CA99: WW Python 2... where is the fun in that... also... it's not automated ... think of what i'm building as a automated watergun turret... with the option to be quickly transformed into a handheld

and again... really it's all about the build.

Here is a question that i was trying to figure out... maybe one of you can point me in the right direction...
if i have 100oz vessel with 4500psi of air pressurizing another vessels to 100psi how long can i hold the trigger open before i run out of pressure? lets assume the water comes out of a 3/16th hole.

Re: Concept Watergun using 4500psi HPA tank to supply pressure

Posted: Sun Jun 01, 2014 2:43 pm
by martianshark
In that case, just go with our original suggestions (minus the ball valve suggestion), and turn up the PSI when in water fights.

I don't know how to figure out the answer to your last question. Someone else might be able to, but if they don't, you may just have to do some testing. If you do intend to use this in water fights, we would recommend a higher capacity, as we said before.

If you set it up so that it shoots out 1oz/second (fine for cat-spraying), then obviously, it will last you 100 seconds. If you hook it up to a shower nozzle, which would be more effective, it would probably require 2-3 oz per second, and thus would last 50 or 33 seconds. This is assuming the tank can be filled entirely with water.