question about APH

Build a homemade water gun or water balloon launcher and tell us about it.
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Lowii
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Joined: Tue Jun 19, 2007 4:09 am

question about APH

Post by Lowii » Tue Jun 19, 2007 4:18 am

Hi, I have a couple questions about making the APH (by DOOM) decribed on this website. First, if you do not plan on using the optional backpack, can you just replace the lower check valve with an end piece, or is it still important.

Also, I am not sure how you fill it with water.

Thanks in advance for any help.

-Jonathan

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Silence
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Joined: Sun Apr 09, 2006 9:01 pm

Post by Silence » Tue Jun 19, 2007 4:25 am

Welcome to the forums! :)

In case you didn't know, since the article didn't mention it, the backpack used is usually one detailed in the backpack mod article. You can use pretty much anything you want, though. Many water guns have PVC backpacks or PVC reservoirs on the water gun itself.

No matter what type of reservoir you use, you'll need a check valve between the reservoir and the pump. The animation in the HowStuffWorks article shows how the check valve setup correctly channels the water.

Oh, and Doom is now known as Ben (the webmaster), in case you see him on the forums. :cool:

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SSCBen
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Post by SSCBen » Tue Jun 19, 2007 11:33 am

Sadly, I never went into depth about the different options for water reservoirs in that article. An overhaul is long overdue. I apologize for not getting the overhaul out sooner. Let us know here if you have any questions and we'll answer them for you. ;)

all_washed_up
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Post by all_washed_up » Tue Jun 19, 2007 4:13 pm

The one thing I could not find at the store was a PVC check valve. They had only one type, and it was quite large and made of rubber. Does anyone have an online source for a small PVC check valve?

Thanks

a_w_u

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SSCBen
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Post by SSCBen » Tue Jun 19, 2007 4:34 pm

You can find most anything you might need at McMaster-Carr. I would suggest buying two of part number 46835K52. ;)

Lowii
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Joined: Tue Jun 19, 2007 4:09 am

Post by Lowii » Wed Jun 20, 2007 7:02 pm

thanks for the help. I understand whats happening now. I glued most pieces together - everything from the last checkvalve to the nozzle, and most of the other pieces. I am having trouble building up decent pressure. Do I need to glue everything to get good pressure?


Jonathan

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SSCBen
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Post by SSCBen » Wed Jun 20, 2007 9:03 pm

If you glued everything from the first check valve to the nozzle, you should have no problems getting pressure. I'll help you troubleshoot though. Answer the following questions.

By first check valve, do you mean the one before the pump?

What diameter is the pipe you used for your pump?

Is the pump seal leaking?

Is the pump sucking up a lot of air? The pump may feel "bouncy" if it is.

Are there any visible leaks?

How strong are you?

These questions will help determine why you're not getting adequate pressure. :)

Lowii
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Joined: Tue Jun 19, 2007 4:09 am

Post by Lowii » Wed Jun 20, 2007 9:20 pm

Hey, I just glued everything together completely.

...My pump is 1/2 in.

...The pump seal is very tight. I used a rubber stopper that was a little too small to fill the 1/2 in. pvc, sp I wrapped it with duct tape, then wrapped that with a lot of teflon tape to make it pump smoother. The end result is pretty tight.

...It gets to a point where it doesn't want to suck in more air in the back check valve.

...There are no leaks at all.

...I am pretty strong. :)


It seems to get to a point where it is no longer pulling in air ( from the back check valve) on the out strokes of the pump (my check valves stops honking).

Thanks, Jonathan

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Scavenger
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Post by Scavenger » Wed Jun 20, 2007 9:25 pm

That should work fine with water. The problem is you're pumping air, which compresses a lot more than water. The pump is designed for water, it won't build up very much pressure with air because of the space between the rubber stopper and the two check valves.

Lowii
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Joined: Tue Jun 19, 2007 4:09 am

Post by Lowii » Thu Jun 21, 2007 12:06 am

Ha! It works perfectly! Thanks for the help.

Jonathan

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