pressurized backpack water gun built

Homemade water gun threads that are notable.
coolocat
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Joined: Fri Jun 27, 2008 7:45 pm

pressurized backpack water gun built

Post by coolocat » Sun Jun 29, 2008 5:16 pm

Hello everybody I'm new to the forums and I thought I'd post details of a pressurzied backpack water gun I built recently.

I thought that this water gun would be easier to build as I live in Ireland and we don't have the range of pvc that is in the US. Though I am planning a copper aph soon.

Anyways the gun has excellent output and shot time with not much pressure drop off and the range is decent I reckoned it be about 45-50 feet.

But they say a picture says a thousand words so here are a few: :)

Pics:
http://i288.photobucket.com/albums/ll18 ... ge0058.jpg
http://i288.photobucket.com/albums/ll18 ... ge0056.jpg
http://i288.photobucket.com/albums/ll18 ... ge0053.jpg

Any questions are welcome:

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Specter
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Re: pressurized backpack water gun built

Post by Specter » Sun Jun 29, 2008 6:04 pm

What kind of pipe did you use for the backpack? It looks like PVC but it's brown. Or is that just the kind of PVC you have there in Ireland?
My "arsenal": Customizable APH, Storm 600 pistol (still haven't finished fixing this), launcher- Model:AB1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future
My site Image My website/forum is back up and running, for the most part after it having been deleted in october

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Silence
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Re: pressurized backpack water gun built

Post by Silence » Sun Jun 29, 2008 8:41 pm

Welcome to the forums! :)

That's a simple, clean water gun. I'm guessing a direct connection to the hose both fills and pressurizes the tank, along the lines of the 2-liter homemade.

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SSCBen
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Re: pressurized backpack water gun built

Post by SSCBen » Mon Jun 30, 2008 2:50 am

Looks straightforward and well executed. It might be a little tall for me, but that's all relative to the size and preferences of the user. The only problem I could see are the coupler things. The one that leads to the hose isn't at the bottom so you have a good deal of dead space, though you're probably limited by available materials.

You also could try some different nozzle sizes to see what works best. Looks to me that you're using an air coupler as a nozzle at the moment. Look for some flat threaded caps or something you could drill holes in and try some different nozzle diameters. Most of the time the ideal diameter will add 5 or more feet of range to your water gun compared against what you started with (unless of course you started with the ideal diameter!).

I'm looking forward to your copper APH. We haven't had too many of those made so any finished products are great news. :)

aEx155
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Re: pressurized backpack water gun built

Post by aEx155 » Mon Jun 30, 2008 3:39 am

SilentGuy wrote:Welcome to the forums! :)

That's a simple, clean water gun. I'm guessing a direct connection to the hose both fills and pressurizes the tank, along the lines of the 2-liter homemade.
Well, by the looks of it, it seems to be very closely built like RolandTower's design, but with a little differences made I guess to adjust to available pieces. It looks like there's "saddle tee connectors" for filling in the upper left, a schrader/presta valve in the upper right (I can see a bike pump in the lower right corner), and an outlet in the lower right (It seems like it was tapped into the cap, although I'm not sure whether or not he used reducers...). Nice design.

I bet the brown color has nothing to do with pressure ratings and is purely location-dependent...although I could be wrong. Could you clarify coolocat?

The only suggestion I would make would be to try and get the outlet as close as possible to the bottom of the backpack, as it allows you to get the most out of the water you put in.

An alternative, although not the best solution, would be to fit a pipe/hose on the inside leading to the bottom, like a feed tube. Just a suggestion...

It would be nice if you could provide some stats on the gun.

Good job overall though, looks like a good gun.

coolocat
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Joined: Fri Jun 27, 2008 7:45 pm

Re: pressurized backpack water gun built

Post by coolocat » Mon Jun 30, 2008 4:03 pm

Hello people I'm back you've all pretty much summed it up. The pvc pipe is basically sewer pipe and brown is just the colour of it over here. I had to use saddle tee connectors for the inlet to the hose and the filling part as its impossible to get a tee joint like roland towers had here in ireland.
Yah there is a lot of dead space in the reservoir and that unfortunately was a design flaw that i only realised after i was finished :) but i'm not sure i could have made a good seal with the saddle connector at the bottom. I used a schrader valve to pump in the air into it.

I am planning on using different nozzles to see which ones i get the best range coupled with a decent amount of output. I'll test it out more and post back with more accurate statistics.

Anyways about the copper aph I'll start building it this week and i'll keep ye posted

Any more questions are welcome :)

aEx155
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Re: pressurized backpack water gun built

Post by aEx155 » Mon Jun 30, 2008 4:47 pm

Do you know how much water is left in the reservoir after firing? Also, how much do you usually put into the gun before you pressurize it?

Could you get the pressure rating for the pipe? Or, what the pipe says on the side (you can see it in the picture) It would be interesting to know if that's any different from what we have here.

Here and here are examples of people who are building/built copper APH(s) that you might want to look at. Just to help.

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Silence
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Re: pressurized backpack water gun built

Post by Silence » Mon Jun 30, 2008 5:06 pm

And joannaardway's copper precharger water gun and insanitys_engineer's one. We do have a page, but it's rather sparse.

It looks like you already do have a good nozzle. You may want to try a slightly larger one, but if it's a drilled endcap you probably won't achieve the same lamination and range.

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SSCBen
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Re: pressurized backpack water gun built

Post by SSCBen » Mon Jun 30, 2008 9:03 pm

If you could make a guide to the construction of your copper APH us here would greatly appreciate. We're getting more visitors from places where PVC pipe isn't readily available so alternative guides are in high demand. ;)

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Drenchenator
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Re: pressurized backpack water gun built

Post by Drenchenator » Tue Jul 01, 2008 1:37 pm

Welcome to SSC!

Nice gun! The stream's very solid looking. The only problem with the gun is where the gun attaches to the backpack as you have already pointed out. Still, it should be a real monster on the battlefield.

Do you know what kind of output you're getting. The shot picture looks like about 5x to 10x, but I'm sure it's capable of more.
The Drenchenator, also known as Lt. Col. Drench.

coolocat
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Re: pressurized backpack water gun built

Post by coolocat » Tue Jul 01, 2008 7:00 pm

aEx155 wrote:Do you know how much water is left in the reservoir after firing? Also, how much do you usually put into the gun before you pressurize it?

Could you get the pressure rating for the pipe? Or, what the pipe says on the side (you can see it in the picture) It would be interesting to know if that's any different from what we have here.

Here and here are examples of people who are building/built copper APH(s) that you might want to look at. Just to help
I usually put about 2 gallons into the reservoir and then pressurize to about 80 psi.

unfortunately I couldn't find anything about the type of pressure rating system we use here but it could be the same as the US perhaps but I'll keep looking. The writing on the side is just the length of it and the manufacturers name.

While I was looking I found some interesting statistics about pvc piping I'm not sure whether it matters or not but heres the link
http://www.engineeringtoolbox.com/pvc-c ... d_796.html

Ben I'd be happy to write a guide about how to build a copper aph but I must make sure to write things down as a go along lol :)

Drenchenator I'm not sure of the output but like you said its about 10x. I used a 1/4" air coupler as the nozzle.

coolocat
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Re: pressurized backpack water gun built

Post by coolocat » Wed Jul 02, 2008 12:28 pm

I've been looking at the different copper aphs that are around the forums. They all seem to use a plastic bottle as the pc. On Aurums thread about his copper water gun his idea about using a copper pc intrigued me so i think i might build a copper pc like he's doing but I'm not sure its possible to do . One more thing I wonder would welding copper pipe together in construction of it be possible or would it be too leaky

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Silence
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Re: pressurized backpack water gun built

Post by Silence » Wed Jul 02, 2008 2:15 pm

Welding it (or even soldering it, or using JB Weld) would work fine. The only things is that it is much, much easier to take apart and rebuild a water gun that uses metal pipe nipples (essentially, lengths of pipes with male threads carved on the end) and female threaded fittings. If you make a mistake here or want to recycle the parts later on, that's not possible with welded metal.

Threads should offer a fine seal, at least if you use Teflon tape.

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cantab
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Re: pressurized backpack water gun built

Post by cantab » Wed Jul 02, 2008 9:15 pm

I believe compression fittings are usually solid enough as well - they're used for mains water at least. They're if anything probably even easier for disassembly than threads, since you don't need to rotate any pipe or fittings, just the nuts.

Soldered ('capillary') fittings will make for a lighter and possibly sleeker design, but are more permanent and a bit harder to make, though I think you CAN desolder them. You can get fittings that come with a ring of solder in them, so all you have to do for your first use is put together and heat (if you reuse them you have to feed new solder in the end).

I think there's really no need to weld copper.

Also remember you can bend copper pipe. Either by using bending springs that you put inside, and then bend it over your knee, or with fancier devices, which are better for the larger sizes (it's hard to bend the really big pipe by hand). This will give much better flow characteristics than elbow fittings (because it's a wider curve), so if you need a direction change between the PC and nozzle (and will with an APH), I'd suggest bending. You might also find you like the look better (fancy a water gun that looks like a brass instrument?)

I think I've seen a homemade copper gun with small metal PCs. Can't remember whose it was.

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Silence
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Re: pressurized backpack water gun built

Post by Silence » Wed Jul 02, 2008 11:52 pm

I haven't heard of any copper water guns with metal PCs. It's not in the threads that aEx and I linked to earlier. Weird.

Heh, I forgot about compression fittings. Those aren't used at all with PVC so I suppose it just slipped my mind. But I agree they'd probably be better than threads/welding/soldering for seals, space-saving, and reusability.

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