Displacement Pump

Build a homemade water gun or water balloon launcher and tell us about it.
Locked
User avatar
Silence
Posts: 3825
Joined: Sun Apr 09, 2006 9:01 pm

Displacement Pump

Post by Silence » Mon Apr 24, 2006 1:43 am

If you've looked at enough of my posts (if not, try "PreCharger Homemade"), then you probably know that I am a big fan of homemades that allow you to use the ball valve like a trigger because of its proximity to the grip. Of course, with most homemades this can be a problem; the ball valve must be in front of the PC(s) and near the front, while the grip is usually the pump-PC connection tube and near the back--this means that you must use extra tubing in the connection tube. While it might be an inefficient workaround, this concept is one solution to this problem.

If the pump-PC connector attached near the front of the pump tube, then the gun would be sturdier, require less tubing, and would position the ball valve "trigger" next to the connector grip.
Image
Basically, instead of pushing the water out of the pump tube, there is no piston; the pump, which has an outer diameter (OD) that is almost the size of the inner diameter (ID), displaces the water that was originally inside the tube; this water is then forced out and into the CPS bladder, or whatever chamber is used as the PC.

The seal is created by an O-ring that is fixed at the mouth of the pump tube. Somehow, possibly through a tracked pump, the pump must be kept parallel and aligned with the pump tube.

This is only a rough draft, and it is horribly inefficient when compared to true pumps, but it might have some potential. And before anybody rudely shoots me down, please understand that I'm just expanding the knowledge of the soaker community :) .

User avatar
m15399
Posts: 224
Joined: Sat Oct 15, 2005 1:54 am

Post by m15399 » Mon Apr 24, 2006 1:57 am

It would work, but you will probably have some problems with the seal.

I can see why you might want this... but then you would need to have the reservoir in front of the PC or on top to balance it.

User avatar
Silence
Posts: 3825
Joined: Sun Apr 09, 2006 9:01 pm

Post by Silence » Mon Apr 24, 2006 2:06 am

I don't see any problems with the seal, but you did alert me to another problem: how would one attach the O-ring to the inside of a tube? That would be a little difficult.

m15399 (Post #2)
I can see why you might want this... but then you would need to have the reservoir in front of the PC or on top to balance it.

Why must the reservoir be in front of the PC? I think my diagram itself shows that the reservoir may be mounted just like those in any other homemades. It could either be top-mounted or in a backpack.

User avatar
DX
Posts: 1780
Joined: Wed Feb 04, 2004 1:00 pm

Post by DX » Mon Apr 24, 2006 2:22 am

It all depends on where you plan to grip the soaker. In no two homemades do I use the same exact area for a grip! Different designs call for different areas to hold the gun, finding a design that gives a nice grip is a goal. All you have to do is alter designs to put the valve near where you want to grip. Don't have to do anything special, such as altering the pump. That might not work if the shaft is not exactly the right size and if the seal is not exactly perfect. You would need high precision for this.
Mess With the Best, Get Soaked Like the Rest!

2004 Red Sox - World Series Champions
2007 Red Sox - World Series Champions!

User avatar
m15399
Posts: 224
Joined: Sat Oct 15, 2005 1:54 am

Post by m15399 » Mon Apr 24, 2006 2:46 am

It has to do with the balance. You will have to hold it on your shoulder like a bazooka if the reservoir is behind the PC/grip. You want the majority of the weight to be on the grip, not behind.

User avatar
Silence
Posts: 3825
Joined: Sun Apr 09, 2006 9:01 pm

Post by Silence » Mon Apr 24, 2006 2:50 am

Well, I've almost given up on this idea anyway. As I said before, it would be hard--no, impossible--to secure the O-ring within the pump tube. That in itself, together with an inefficient and otherwise flawed design, kills the concept.

EDIT: Didn't see m15399's post. It makes sense, and I was dealing with the balancing problem earlier anyway--I just couldn't link this to the "reservoir in front of the PC." Currently, my solution (actually, it's better than a displacement pump) is to have a slanted pump-PC connector. See the current (mid-/late-April, for future readers) diagrams in the "PreCharger Homemade" thread.

User avatar
Silence
Posts: 3825
Joined: Sun Apr 09, 2006 9:01 pm

Post by Silence » Mon Apr 24, 2006 9:01 pm

Yeah, I'm really happy with my other solution (the slanted connector tube and second check valve). It (1) allows for the use of standard pumps ;) , (2) it allows for a slightly more linear flow, (3) it moves both the pump and the grip back along the line of the soaker, (4) it allows for the ball valve to be used like a trigger, and (5) the slanted design allows for a theoretically more comfortable grip. I think that I had more arguments, but these were enough to wrap this up (for me, at least).

Locked