View Full Version : water spitter
Frightful Nights Haunted
12-03-2008, 05:29 PM
I am looking for a great how to on making spitter mechs. There is not much online and would figure there would be, but nothing. I know of a place to buy them, but feel that $400 for them in too high, based on looking at the pics what they are made of.
i am also just woundering why it is such a big secret what the little metal cube in the spitter is. This isn't nuclear bomb design were talking about.
Any how tows for submerged or dry applications would be great OR just a good direction of where to go looking. If I get a basic idea of it then I can run with it and adapt if needed.
all i am mainly after is what is they little part that all of the hoses hook up to.
any help would be a great.
12-03-2008, 06:08 PM
dude i swear this is a secret. haha
ive looked everywhere and asked tons of people and cant find one either.
im dying to know how.
i think i may have found out a way using a three way valve, pond pump, and solenoid. but not sure yet.
Frightful Nights Haunted
12-03-2008, 06:31 PM
i am thinking that it is a siphon effect were when air is applied to the cube, it pulls the water and mixes with the air and them comes out of the tube with the nozel on it. i thought about useing this part http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200137124_200137124
in not shure if it would work.
12-03-2008, 06:55 PM
hey bro I had this problem last year but I finaly figured out somthing out a real simple fix and way cheaper........ I have used this on my outhouse prop for the last 2 years with know problems. I also have another new way were using but all post that after no real pics or vids of that set-up but here is an easy set-up....
and here we upgraded the size of the water botole last's almost a week with 500 guest's.
12-03-2008, 08:15 PM
frightful nights i think that part might work, dang that would save a lot of money if it did. let me know.
OK Northern, how is the water coming up the hose. Is it a vacuum being created when you blow the air through the end???
12-03-2008, 11:26 PM
I saw a parade car that had windshield washers cranked up so much that they could soak people standing along the road in the parade crowd, maybe 25 feet away!
Howd they do THAT?
12-04-2008, 08:18 AM
The concept is the Venturi Effect. Google it for more information, but here's the general concept. When a fluid (in this case air) is flowing through a pipe it can be characterized by Bernoulli's Equation. A simplified version of that equation says:
P + 1/2 p * v^2 = constant
where P is pressure, p is density, and v is velocity. The Venturi Effect describes a case where the cross section of the pipe quickly decreases for a moment. If you take a point just before the change and call it point 1 and take a point inside the reduced cross section and call it point 2 you can make Bernoulli's Equation to say:
P1 + 1/2 p1 * v1^2 = P2 + 1/2 p2 * v2^2
P2 = P1 + 1/2 p1 * v1^2 - 1/2 p2 * v2^2
If you take real data and plug it into this equation you'll find that the pressure inside the reduced cross section is less than that in the larger cross section. In other words...you have a vaccum. If you tap into that section you can use the vaccum to draw water into the air stream.
Okay...now a simpler answer. If we go back to the previous work we can see that, for our purposes here, the faster the air moves through the pipe the lower the pressure. Well, the air moving through the pipe is always moving faster than the air outside of it which isn't flowing at all...so there is always some vaccum in the pipe compared to the outside air. If you tap into any pipe with fluid flowing through it you can access a vaccum...just not as powerful as the one described above. For the simple approach, just be sure that the tube you use to bring water in is significantly smaller in inside diameter than the tube air is flowing through or it won't work. It should be somewhere around 2 to 4 times smaller...but you'll have to experiment to get it right.
That has been todays lesson in fluid dynamics. Thank you all for your kind attention. Class dismissed. ;)
12-04-2008, 08:26 AM
Okay...so...I never actually watched Northern's video until just now. That's pretty clever all it's own. It't the same general concept, but instead of tapping the vaccum within a tube of flowing air he is injecting the air into the larger tube and the flowing air in the front of the tube creates a vacuum strong enough to draw in water from the back. The only probelm that I can see is that the tubes are orientation sensitive. If the air tube coming in isn't situated right in the water tube the air will just flow back into the water bottle. At any rate...I like it. I've never seen one done like that before.
12-04-2008, 03:34 PM
The technical word for them is an eductor. It uses a venturi effect to create a vacuum that can draw a fluid into an air stream. Mostly they aren't designed to do this, because there really isn't much use for that in industry, but as long as you get an air eductor it'll pull enough to draw water from a local reservoir.
McMasterCarr sells them part # 4977K31
They also have this comapny called EX Air whom I like that sells aluminum ones for a little cheaper and they won't rust.
So yeah they do exist and they are used all over the place, you just didn't know the right name to search for.
kpolley - that's some cute little equations you have there but unfortunately those are based on Bernoulli's principle and only hold for an incompressable fluid. And for some reason i'm going to say that compressed air is a compressed fluid. At which point you get into some pretty nasty differential equations to define mathematically the principle works. But it does work none the less so who cares about the math behind it.
Northern Touch - That's a hell of a rig buddy, but wouldn't it have been easier to just buy an eductor?
12-04-2008, 03:44 PM
Thankz guyz I played around with a few ideas before we came up with this but I also have a simple way using a cheap airbrush gun! And washing mashing solenoid to fire at will all try and take apart one of the new spitters we just built to show how easy this set-up is.
12-04-2008, 05:17 PM
Actually, the equation is quite applicable to this situation. It is common practice to consider gases to be incompressible if there velocity is considerably below the speed of sound. Experts range wildly on how far below the speed of sound the velocity needs to be but I have read texts that suggest Mach .7 is the transition point at which Bernoulli's equation becomes unusable. Since I doubt the air is traveling at 7/10 the speed of sound it would be a completely reasonable assumption that the flow is incomopressible the same as it is to drop the g and z variables from the equation which account for acceleration due to gravity and elevation. According to your statement, no air flow could ever be characterized by Bernoulli's Equation when, in fact, the equation is applicable to many air flow scenarios. In fact, most definitions or descriptions of the Venturi Effect reference Bernoulli to explain the concept. In addition, I spent several years doing some very extensive air filtartion testing for the US military on a test rig I designed, built, and automated and the military had us use the exact same assumptions when calculating pressure differentials. I think if you look at MIL-PRF-46736E you'll find Bernoulli's Equation in the Appendix where it discusses air flow calculation...but I don't have the standard in front of me right now. At any rate, if it's good enough for the Army's Tank and Artillery Command it's good enough for me. Bernoulli is completely applicable here.
12-04-2008, 06:19 PM
Thank you professer Polley, once again the world can revolve in greased grooves.
12-04-2008, 06:36 PM
What are you smok'n!!? I want some.
"Actually, the equation is quite applicable to this situation. It is common practice to consider gases to be incompressible if there velocity is considerably below the speed of sound. Experts range wildly on how far below the speed of sound the velocity needs to be but I have read texts that suggest Mach .7 is the transition point at which Bernoulli's equation becomes unusable. Since I doubt the air is traveling at 7/10 the speed of sound it would be a completely reasonable assumption that the flow is incomopressible the same ad it is to drop the g and z variables from the equation which account for acceleration due to gravity and elevation. According to your statement, no air flow could ever be characterized by Bernoulli's Equation when, in fact, the equation is applicable to many air flow scenarios. In fact, most definitions or descriptions of the Venturi Effect reference Bernoulli to explain the concept. In addition, I spent several years doing some very extensive air filtartion testing for the US military on a test rig I designed, built, and automated and the military had us use the exact same assumptions when calculating pressure differentials. I think if you look at MIL-PRF-46736E you'll find Bernoulli's Equation in the Appendix where it discusses air flow calculation...but I don't have the standard in front of me right now. At any rate, if it's good enough for the Army's Tank and Artillery Command it's good enough for me. Bernoulli is completely applicable here."
12-04-2008, 08:27 PM
Instead of running various control lines for electric, or air lines to do something, just have the customers step on a flat surface that has used enema bags full of water under it. This goes to a small diameter hard plastic metal/copper tubing to the squirter, think brake line tubing and fittings. Drill a small hole in a pipe plug or perhaps the small tubing alone IS the size of the stream. Practice trying to shoot in the center of a toilet seat. Remember to lift the lid.
Bingo they also happen to be located where the squirting will take place. If you just can't take the shrine down to Bernouli, have the bladder on the ground be ambient air filled at a pressure generated by the customers weight. What is that awful smell? The fun part of this calculation is that the real heavy weights get soaked harder than a 2 year old with asthma or the later may not set it off at all.
Refilling air or water in the bladder is done as the plate flexes back to a position of rest drawing from an off site reservoir for liquid that is higher than the pad or for air nothing at all, the squirter end is open. No real reason for check valves or anything complicated that can fail if the tubing sizes are right. In fact this is the relief that if your system is walked upon by a Rhino it doesn't explode.
A more industrial version of the enema bag would be a hydraulic accumulator back filled with pressure with out the schader valve in place. Yet I like the idea of being able to reveal USED enema bags as the source.
To do Jims Query of windshield washers shooting 25 feet, it is misusing a 12 volt air compressor carry in case of emergency, to cycle water rather than air. Totally the same principal as a regular diaphram washer pump for a car only bigger, faster and thus more distant monkey pissing capability for you clown car.
Prototypes for the squirter can be done by taking one of those little frog toys that when you pump the little bulb, the frog legs kick out and it moves. Now, when mommy isn't watching take Mister Frog under water during your bath and the little vent hole it has to take in air, now full of water is the desired squirting effect. It will break after about 20 cycles and you will cry because your toy is un repariable but, then you have the principals down to make it stronger faster better than it was before.
You will have visions of Pulitzer prizes but try to stay focused. You are just trying to pee on people with out using your own internal bladder and adjustable orifice tube and still not hit the seat.
Really huge versions of this principal would use a water bed as the bladder, some heavy plastic plastic floor pad like office chair rug protectors as the flexible walking surface and multiple stream locations. Trying to walk on a too thick a movement surface like the water bed is the distraction that can be limited by having an outside frame and a wooden panel system over the carpet protector plastic.
Enjoy your bath. Don't blow bubbles, stay focused.
12-05-2008, 08:38 AM
Don't try and correct me when you are still wrong. Dude what is the difference between super-sonic, and sub-sonic flow? Hint, it's not just the speed of sound, it's where the air starts to compress around the body traveling at that speed. So you're telling me your air ventilation systems were using compressed air? No you were using fans at extremely low velocities. So how does NASA do mid range super-sonic wind tunnel testing? They use compressed air. For Mach 1.5 you only need about 130psi. And I helped to build one of these for NASA, woohoo lets throw names around.
Look we refer to it as compressible and incompressible flow for a reason. Look at your little wiki page again, it says incompressible flow. When you push compressed air through these things it expands, no where in Bernoulli's equations, nor the stuff you posted does it take into account the volume changing. So explain that to me. 1cm^3 goes in and 8.5cm^3 comes out.
Now why in gods name would you even bother to put any of that up here? Do you think most of these people really care? You trying to make yourself look smart is that it? If you are so damn good at this why couldn't you tell them what an eductor was? Look buddy you want to continue this conversation feel free to email me.
Some poor dude asked a simple question that needed a simple answer and you plaster him with math BS. I'm sure that's exactly what he wanted.
12-05-2008, 09:23 AM
No, actually...we were using massive volumetric flow rates in our testing. So incredibly high, actually, that we had to have enormous blowers custom made to handle the pressure and flow requirements. At peak, we were pulling 480cfm through the system at 50iwg. And, to ensure proper suspension of dust particles in the air stream we used a compressed air nozzle inside the inlet pipe. Also, it's funny you suggest that there is no mention of volume in the equation...since density is a function of volume and the equation clearly has a density component. But, I took your advise and hit Wikipedia...guess what I found..."In most flows of liquids, and of gases at low Mach number, the mass density of a fluid parcel can be considered to be constant, regardless of pressure variations in the flow." You say NASA uses compressed air to create velocities of Mach 1.5...I don't doubt that. You are, however, confusing the issue. If you really know anything about the topic then you know that there are a million factors at work here and to suggest that the compressed air we are using in pneumatic lines is breaking the sound barrier, or is even pretty close to it, is crazy. Where's the sonic boom?
You obviously have a chip on your shoulder about something and I really couldn't care less what it is. You seem to think you're an expert on fluid flow and I'm tired of arguing with you. You're rude and obnoxious. I only thought some people might be interested in a brief explanation of the concept behind the Venturi Effect which Bernoulli's equation is absolutely capable of doing. You're right, I should have never got involved in the first place. Silly me for thinking that I could share a little bit of my knowledge with someone who was looking for it. On this, we'll just have to agree to disagree but I'm tired of talking about it with you.
12-05-2008, 11:51 AM
My head hurts, could you guys bring it down to a high school level.
12-05-2008, 02:34 PM
I'm really glad you've found a happy place. So what part of when I asked you to email me did you not understand. But OH, you just had to look like the big man in front of everyone didn't you.
Lets see 50iwg is the equivalent of 3psi. That's some serious compression there paw paw. Wake up.
And density is consider a what in the equation? A constant of yes, so how can you have a compressible flow which is going to change volume, with a constant density. Man that doesn't work, awe piss.
A sonic boom is created by a body moving through a fluid at greater than the speed of sound. In this case you are moving the fluid. And what do you think that crazy wooshing sounds is?
You love Bernoulli so much, you're going to teach everyone how this works, so why don't you go ahead and use those equations to calculate the velocity of a flow with 100psi differential? Let me let you in a little hint here, your answer will be wrong, because you're using the right equations, but you'll get the point.
Now what is right? Well Thomas Kegel wrote a really good paper back in the 70's regarding exactly this topic. He wasn't quite right either, but started on the right track.
And you are absolutely right, there are alot of factors at work here, and it's even worse than you think because you are stepping into compressible world now. Hell incompressible flow is easy, crap college freshman can handle those basic equations, just a little algebra.
So once again I'll give you an invitation if you want to discuss my aerospace and computational fluids backgrounds, along with why people trying to act smart who really aren't pisses me off, I will be more than happy to, but not here. Email is for things like that. So man up and quite being a jackoff in front of your little friends. But that's not really the point is it, the point was always to make people think you were smart, and now I'm a threat to that. Awe poor baby. If you actually had some substance to any of this you would have emailed me, and we could have discussed it. Hell man maybe you could have taught me a thing or two. So go ahead make your pathetic little comeback post. You've already convinced me that you are way above your head here. And honestly why have I even wasted my breath, this is like trying to teach quantum theory to a pre-schooler. Oh yeah, because people like you piss me off and I was really bored today.
And remember you're done with this right?
And now for the simple version.
If you design a nozzle with two holes in the correct way you can actually create a suction on one of those holes. The reason it works is because the nozzle is designed so that the pressure inside of it actually drops below the outside pressure. So it wants to suck stuff in. The physics and math behind it can be a bit daunting, obviously, but at the end of the day it is just a simple static mechanical device.
So you take one of these little guys, shoot some air through one hole and it sucks water up into it through the other. Instant water gag. You can buy them all over the internet, as a said before, and they are really easy to install and use.
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