My APH

Build a homemade water gun or water balloon launcher and tell us about it.
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Simmo
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Joined: Sat Jan 01, 2005 5:52 am

My APH

Post by Simmo » Mon Mar 06, 2006 8:59 am

Hi all, first post here.
I'm finally building my first APH. I follwed the same design as the one on this website. One change I am thinking of making is adding a bike/car valve instead of the pump. Will this standard valve handle the pressure? Also my PC's total 3 liters of water, is that more than ideal? Will this restrict performance in anyway? More posts later on my gun. (In a hurry.)
Thanks.

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joannaardway
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Post by joannaardway » Mon Mar 06, 2006 4:07 pm

You must have a pump, unless you are building a pressurized reservoir, and then you can pump in air using a compressor of sorts, otherwise the water won't get into the PCs.

You could put water into the PCs using a pump, and then use a car/bike valve to force extra air into the PCs to increase power, but unless I am totally misunderstanding you, I don't believe that what you are detailing would work.

Unless water is in the PCs it won't fire and a bike pump won't do that job (it sucks air from the surroundings and then forces it in - it won't act like a water gun pump.) A pump is essential.

Short version: A tire valve will hold the pressure in the PCs if well sealed (and could be used to add more pressure), but cannot be used to load the PCs.

3l sounds like a lot of pumping. A set that added to 3l with valves allowing you to shut them off might work, but 3l will have you there forever, and as an APH, if the PCs aren't well filled, you will have low range and output.
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SSCBen
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Post by SSCBen » Mon Mar 06, 2006 8:56 pm

You will need a pump in the separate pressure chamber homemade water gun design. The water itself has to move into the pressure chambers, as
joannaardway mentioned.

A valve to attach to a bike pump or compressor could be used in a pressurized reservoir based system or as a secondary way to build pressure in a separate pressure chamber system.

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kevinthenerd
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Joined: Wed Apr 05, 2006 4:14 am

Post by kevinthenerd » Wed Apr 05, 2006 4:27 am

Schrader valves that you can get in the automotive department are prety stong. They'll probably handle more pressure than the PVC you attach them to. The problem I've had with them, however, is mounting them without coming out. Put the fat end on the inside to prevent it from shooting out and hurting someone, but make sure it's well mounted to not go back inside.

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kevinthenerd
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Joined: Wed Apr 05, 2006 4:14 am

Post by kevinthenerd » Wed Apr 05, 2006 4:30 am

I'll be using a schrader valve in my next design. I'll probably be using an air compressor rated at 200+ psi, so PVC won't be my first material of choice. (Be careful with that stuff. For safety's sake, use low pressures, well below 100 psi if you want to stay safe. For example, ideal conditions are for about 70 degrees F (21 degrees C). If you use your PVC at 100 degrees F (38 deg. C), which isn't too uncommon for direct sun outdoor play, you'll only get 60% of its maximum strength. (110F/43C yeilds 50% strength!) If you add a factor of safety of 2 (for unexpected forces, like if you drop it or something), you should only be using 30% of the strength. If the pipe is rated at 300 psi, you shouldn't go above 90 psi in these conditions.

It's just something to consider for high-powered custom applications.
Last edited by kevinthenerd on Wed Apr 05, 2006 2:42 pm, edited 1 time in total.

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SSCBen
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Post by SSCBen » Wed Apr 05, 2006 10:27 pm

Schrader valves are too much trouble for me. I use an attachment meant for air tools on my compressor-powered water guns. I do have one image of this attachment online: http://www.sscentral.org/images/air-too ... tion-1.jpg

The air tool connection seals excellently and stays in it's place. The only problem might be finding the connector because I'm not too sure about their availability.

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