PVC Water Gun

This is a Water Gun made of PVC pipes and some brass fittings.

I made it such that it can be disassembled for storage and assembled again when required.

The 4 parts its made up of are

1. Air tank (i made it detachable such that i can be used for another similar project)
2. Water Tank (we can use any size regular cold drink bottle, but based on my test during development, i realized it can empty a 2.25L bottle completely just with the stock air tank)
3. Gun T Section (this parts joins Air tank, Water tank and nozzle together)
4. Nozzle (i over did this part, you may just use small brass nozzle or car wash hose nozzle instead)

How to operate

These are the steps below

1. Make sure the air tank valve is closed.
2. Fill air in the air tank through air inlet valve. For this pupose i went up till 100 psi (6.89 bar)
3. If not done yet, then attach the air tank, T section and nozzle togetherAttached water filled bottle to the gun
4. Aim and fire (open the air tank valve)

How it works

As shown in 'Fluid flow diagram', when valve is opened, air goes in to the bottle through a thin pipe. As air is introduced in the air tight bottle, pressure builds up and water raises though the tube and bursts out through nozzle

1. Choose a correct tank
   
   • Make sure its a steel can, so that we can comfortably solder it
   • Bigger the can, the better. (i chose an air freshner can)
2. Make Holes for Connections
   1. Can's top end i used as an air tank extension, and attached the end cap. (used a rubber washer to air tighten it)
   2. Can's Rear end is used to attach the brass valve. (at both the ends of the brass valve, i inserted silicon washers to make the attachment air tight)
   3. Added one hole for the Pressure gauge (used a silicon washer here as well)
   4. Last one hole for the tyre valve to fill the air
3. Attach the brass valve
   • See the pictures for a reference
   • I used a female connector to solder the air tank to, and used male to male brass coupler to attach it to valve
4. Check for air leaks
   • please please please be extreamely carefull while doing this
   • Start testing for low pressure first (i started with 25 psi)
   • gradually keep increasing the pressure
   • These tests will not only confirm solder leaks but joint leaks as well, since major parts are connected and air tightened using silcon/rubber washers.
   • I went up till 100 psi

Make sure you solder work is as clean as possible. I recommend using a blow torch to make sure the solder is evenly spread. My initial attempts using very basic 25 watt soldering iron resulted in air leaks.

1. Make an air tight seal around air tube, that will carry air to the bottle
   • Insert a vynil tube along with conical washer (add additional disc washers to have more space to tighten). I additionally used a brass tube to tighten it properly in the pvc connector
   • Let it pass though PVC T connector.
   • Use a PVC pipe connector to attach a small 6 inch pvc pipe segment to the T section which we will attach water bottle to.
   • Get a cold drink bottle cap and make a hole though it wide enough to slide the pvc pipe through it.
   • Slide the cap to the way up till it sticks to the PVC connector at the top
   • Glue it firmly with the best glue you may get :P, since it should carry 2.5 L bottle filled with water
   • insert a small washer in the cap to make sure when we attach a water bottle, it forms a water tight seal
2. Take out the other end of the air tube from a hole on the PVC pipe segment
   • make a small hole just enough to fit the vynil tube
   • Peek out the tube from that hole, glue it firmly right there
   • slice off the excess tube, file it to make the surface even as rest of the pipe so that water bottle can slide over it
3. Attach flexible rubber tube to the other end of the PVC pipe segment
   • make sure the diameter of the rubber tube is no more that the PVC pipe and its thinner enough to bend according the height of the bottle
   • file 3/4 inch of that segment to fit the ruber tube nicely still not being bigger the the PVC pipe diameter
   • Glue the rubber tube to the PVC pipe firmly
4. Repeat the pressure testing performed in first step, this time with a bottle attached
   • attach a spare PVC end cap to the nozzle part of the T section, so that leakage in the assembly can be monitored
   • you may use a smaller bottle for this purpose
   • you also might want to keep the bottle filled with water to inspect the bubbles, additinally it will also reduce the air volume that is compress, so its safer.

Let me accept the fact that i got carried away with this. I wanted to make a laminar flow to increase the range of the water gun.

The quickest and easiest way to make a faily well nozzle is to attach simple PVC pipe end cap with a hole in it

Another better way would be just attach a brass nozzle used for gardening.

I am still putting the steps just to know your views on this.

1. Started with a PVC female connector so that it can be attached to the T section
2. Added intermediate PVC pipe segment to extend a little bit
3. Added 0.5 in to 0.75 inch expander connector
4. Inserted 0.75 inc PVC pipe segment with a length 2 inches
5. this is the section i am indicating with my hand in the picture bove
6. this is the section we stuff all our scoobie strings
7. attached another 0.75 inch to 0.5 inch reducer to the other end
8. attach conical ruber gasket to reduce the water flow area
9. attach a ballpoint pen body make water flow more pointy
10. Glue this whole assembly with epoxy or similar good quality water proof glue

Additionally we may (should) attach yet another pvc ball valve to have a finer control over the water flow.

(sorry guys for not uploading a video of this gun in action, please follow this project as i am planning to do it ASAP)