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Air pump CPS gun concept

Posted: Wed Mar 30, 2011 2:55 am
by strato_2r5
My idea is that instead of using a homemade pump, because homemade pumps have problems with leaking, we use an air pump, but not have it PR. The idea is that you hook up an air pump to a resevoir. Since air always stays above water, the air will push water down into a check valve located on the bottom of the reservoir. The water will move into a tee with the bladder located at one end and a ball valve at the other. What do you think?

Re: Air pump CPS gun concept

Posted: Wed Mar 30, 2011 3:10 am
by C-A_99
Same issue as with the PR: you will have to re-pump more and more air as the reservoir becomes empty, possibly even more because the water only goes into a PC instead of leaving the blaster directly.

Unfortunately, converting bike pumps to pump water doesn't seem to be a viable option either. The best way may be to explore other type of seals; if we can find something similar to what SS and WW uses as water pump seals (the piston kind of seal), that should get the job done.

In the meanwhile, the best method to build O-ring based water pumps is to use a steel or aluminum dowel (the fact that wood shrinks when its not wet means it won't seal until the wood gets wet and expands, plus it starts leaking once the entire dowel is soaked), and to keep the O-rings in place with epoxy putty. (Regular epoxy and/or gorilla glue may work too.) CPVC spacers don't work well as they must be cut perfectly square and the inside drilled out (merely cutting them vertically so that they open up and snap around the 1/2" rod won't do the job), and they often detach from any glue used.

Re: Air pump CPS gun concept

Posted: Wed Mar 30, 2011 6:10 am
by mysterio
In my personal experience, bottle-blaster type cheapo water guns often have seals that can be reused, with the help of a threaded rod and some nuts/washers.

Re: Air pump CPS gun concept

Posted: Wed Mar 30, 2011 6:26 am
by C-A_99
I guess you could take out the seal out of any cheap piston pumper, but spending $4 just for a seal is kind of meh. Stock pumps are typically too short to work for homemades.

Re: Air pump CPS gun concept

Posted: Wed Mar 30, 2011 12:54 pm
by isoaker_com
strato_2r5 wrote:My idea is that instead of using a homemade pump, because homemade pumps have problems with leaking, we use an air pump, but not have it PR. The idea is that you hook up an air pump to a reservoir. Since air always stays above water, the air will push water down into a check valve located on the bottom of the reservoir. The water will move into a tee with the bladder located at one end and a ball valve at the other. What do you think?
The problem with this idea is that, unlike water, air compresses (which is why it can be used to pressurize a chamber). If you need to pump in air into a reservoir to create enough force to expand a CPS-type chamber, you'd need a good amount of force and may be better off simply hooking that reservoir directly to the nozzle. Sure, if may have more angle restrictions than the rubber bladder would, but if it is power you're after, your system ends up basically having two PCs (sort of like the Hydro Blitz) with the reservoir PC powering the secondary firing chamber PC.

In theory, it would work, but seems like a lot of wasted energy considering that after the reservoir is emptied, it'd still be pressurized a lot while not being able to push out any more water. Direct pumping into an elastic bladder makes more sense to me.

:cool:

Re: Air pump CPS gun concept

Posted: Sat Apr 09, 2011 5:28 pm
by -G-JiV-
SUper SOaker already built up such a gun:

Super Soaker Max-D Secret strike. You push air into the main firing reservoir. The air pushes water into the second, seperate firing chamber, but in this case you have a air-PC and not a CPS bladder as PC...

Works as a back-up option, butit is really MUCH BETTER to push the water to a nozzle and not to a second PC, for back up ok, but really not for main weapon!

You can build a water-pump out of a air-pump. just glue the o.ring in place, close all further holes(may also a PR-valve if existing) drill a hole into the pump's end or cut the hose off and install two check valves to get a water flow in on side. Check where the original check valve is installed, mostly at the end of the pump where the hose is connected.

You can do everything, you just have to really want it ;)

Re: Air pump CPS gun concept

Posted: Sun Apr 10, 2011 2:40 am
by C-A_99
I don't think the MDSS uses a check valve between the reservoirs though. I'd have to check.

The issue with converting air pumps to water is that it involves busting up stuff to get the seal out and exposed. In some cases, you can put it back together effectively, but I'd have to doubt that such a converted pump would be more reliable than the typical homemade pump. I have some new ideas for building pumps however, and I'll be experimenting and trying them out when I can.

Re: Air pump CPS gun concept

Posted: Sun Apr 10, 2011 4:19 am
by soakernerd
I can't find the thread, but didn't SEAL convert a bike pump for use in his APH?

Re: Air pump CPS gun concept

Posted: Sun Apr 10, 2011 5:32 pm
by SEAL
The thread is here.
The issue with converting air pumps to water is that it involves busting up stuff to get the seal out and exposed. In some cases, you can put it back together effectively
Yeah, in my case the bike pump I used was very easy to take apart, convert, and put back together.

The pump has held up so far, but for my CPH (Which I really need to start working on.), I think I will build a regular pump, mainly just to see the difference, and for the experience. Besides, I don't think I have any spare air pumps laying around, and even if I did, like C-A_99 said, it would have to be easy to take apart and put back together.