New Project: Water Cannon

?ukas H?u?t?ler said:
Allright, thanks everybody for your awesome tips. So I found this 12v pump that would do 55 gpm at a 4m head.

More details:
95 Watt/8000 U / min
DC 12 V/13 A
(http://www.amazon.co.uk/Professional-submersible-12600-ideal-yachts/dp/B004J0FJZS)

I found a nozzle that can take it down to 1 cm, do you think it'd work on one or a couple of car batteries? If yes, should I get a tighter pipe (the one I have now is 18 mm) for the cannon to maximise pressure?

Peace,

[EDIT] - Forgot to pot an example battery. How's about this? http://www.amazon.co.uk/Alphaline-0...1WSC/ref=sr_1_1?ie=UTF8&qid=1339169224&sr=8-1
Click to expand...


You may have better luck going with a Deep Cycle Battery.

A Deep Cycle Battery would last longer in that application.


Have Fun, Be safe and wear Eye protection.
 
The pump in your link looks like a bilge pump. With 4 meters of head that converts to about 6 psi. I would think you need more psi to spray farther. I would go with a pump with higher pressure so the cannon will shoot more distance. I would play around with different nozzles to get the distance you want.
Also the pump in your link is a submergable pump, not sure if that is what you need or not. Where do you plan to locate the cannon and the pump? By where I mean is it going to be on a dock, beach, in a kayak, or mounted on the roof of your car? To get good answers you have to provide good information and a description of what you plan to do , pictures help too.
 
Smooky said:
The pump in your link looks like a bilge pump. With 4 meters of head that converts to about 6 psi. I would think you need more psi to spray farther. I would go with a pump with higher pressure so the cannon will shoot more distance. I would play around with different nozzles to get the distance you want.
Also the pump in your link is a submergable pump, not sure if that is what you need or not. Where do you plan to locate the cannon and the pump? By where I mean is it going to be on a dock, beach, in a kayak, or mounted on the roof of your car? To get good answers you have to provide good information and a description of what you plan to do , pictures help too.
Click to expand...

That's what I was afraid of. I've made a couple different nozzles that work great, one of 7 mm, the smallest one 3 mm. Here's a nice drawing of what I'm planning:

Water cannon.jpg

I could be standing on a small yeti as well, but this is basically the confguration. The idea is to be able to fit the battery into this suitcase:

P1120809.jpg

It's 13" x 19,5" x 7,5"

P1120801.jpg

This is the prototype barrel. It's 18 mm ø, 26" long and can be bushed down to 7 or 3 mm at the end by the nozzles I've made. Water will be fed from the right. Would it maximise pressure if I'd use a hose tighter than the barrel to feed the water through the pipe? Or is it equated when the water is forced down to 3 mm?

Thanks again you guys for your great help,

Lukas
 
Many of the 12 volt submergible pumps that I am finding pump a large volume of water but do not produce a lot of pressure. There are a few, but they can get rather expensive. Here are some links to 12 volt pumps. Most of this type of pump is used in motor homes or it is the type used for agriculture sprayers. This type of pump does not set in the water. You would need an intake hose that would be placed in the lake. You need a float or something to keep it from sucking up so much trash and a strainer. The suction hose needs to be hard enough so it will not collapse when the pump starts sucking on it. I would use hose and fittings with at least ¾ inch inside diameter until you get to your cannon, otherwise don’t try to restrict the flow except for the nozzle at the end of the cannon. I believe I would just use a battery box and forget the suitcase. You could always camouflage it some other way or let the yeti hold it.

http://www.all-about-the-home.co.uk/shurflo-on-demand-diaphragm-pump-12v-6843-p.asp

http://www.amazon.co.uk/dp/B006J7VL...de=asn&creative=22218&creativeASIN=B006J7VL8S

http://www.wcsuk.com/acatalog/SHURFLO-BLASTER-WASH-DOWN-PUMP-3901-2204-14-PU48.html

http://www.williamsonpumps.co.uk/

http://www.lilie.com/shurflo/infos-2s.pdf

http://kanubistanker.de/online-shop...ster-Deckwaschpumpe-12-Volt-Frischwasserpumpe
 
Last edited:
Smooky said:
Many of the 12 volt submergible pumps that I am finding pump a large volume of water but do not produce a lot of pressure. There are a few, but they can get rather expensive. Here are some links to 12 volt pumps. Most of this type of pump is used in motor homes or it is the type used for agriculture sprayers. This type of pump does not set in the water. You would need an intake hose that would be placed in the lake. You need a float or something to keep it from sucking up so much trash and a strainer. The suction hose needs to be hard enough so it will not collapse when the pump starts sucking on it. I would use hose and fittings with at least ¾ inch inside diameter until you get to your cannon, otherwise don’t try to restrict the flow except for the nozzle at the end of the cannon. I believe I would just use a battery box and forget the suitcase. You could always camouflage it some other way or let the yeti hold it.

http://www.all-about-the-home.co.uk/shurflo-on-demand-diaphragm-pump-12v-6843-p.asp

http://www.amazon.co.uk/dp/B006J7VL...de=asn&creative=22218&creativeASIN=B006J7VL8S

http://www.wcsuk.com/acatalog/SHURFLO-BLASTER-WASH-DOWN-PUMP-3901-2204-14-PU48.html

http://www.williamsonpumps.co.uk/

http://www.lilie.com/shurflo/infos-2s.pdf

http://kanubistanker.de/online-shop...ster-Deckwaschpumpe-12-Volt-Frischwasserpumpe
Click to expand...

Hey thanks for looking these pumps up.

So I'm looking at this one: http://www.wcsuk.com/acatalog/SHURFLO-BLASTER-WASH-DOWN-PUMP-3901-2204-14-PU48.html

It seems like something I could use, high pressure and all. However, it just pumps 13 liter per minute, 7,8 times the volume of the barrel. Even at high pressure, will this really be enough? Seems to me that the pumps would still need to pump a certain volume to get it right, or am I totally wrong?

Thanks,
 
Here are a few links to Flojet pumps. Some of them can pump up to around 5 gallons per minute. If you nozzel down your cannon and use a pump that has at least 30 psi, it should work very well. You should be able to shoot alot over 12 feet, even at 7 mm.You should be able to find this type of pump with 30 to 60 psi. The higher pressure usually the volume will be less. so a pump that has 30-45 psi and around 5 gallons per minute should do very well. Even a 3 gallon per minute should do pretty good.




http://sports-explorer.shoppingfountainonline.co.uk/228771.html

http://sports-explorer.shoppingfountainonline.co.uk/Flojet.html

http://www.amazon.co.uk/Flojet-3526...1_fkmr1_2?ie=UTF8&qid=1339330085&sr=8-2-fkmr1

http://www.justkampers.com/shop/leisure-battery-110amp-hours-j16859.html

http://www.gocaravanning.com/caravans/accessories/caravan_batteries.htm

http://www.amazon.co.uk/Draper-6680...Z0/ref=sr_1_63?ie=UTF8&qid=1339332319&sr=8-63
 
You will need more tha 5 gpm unless you go smaller on the nozzle. The volume needs goes as the square of the diameter. For instance, if you took my original calc and used say a 9mm nozzle, the reduction in volume would be (9/18)^2 = 0.25, so about 36 gpm*.25 = 9 gpm (plus additional to cover air resistance).

With a 7mm nozzle, the required volume is (7/18)^2 * 36 gpm = 5.444 gpm. Again, this is the minimum fllow required to get the distance.

The design of most things (like this) takes some iteration. In this case, it is like this:

1. pick a nozzle size (based on what is available or how wet you want to get them)
2. calulate the volume
3. calculate the pressure drop
4. look at pump curves to see if there is a pump available (consider price, power requirements, etc) that can meet the volume minimum at that pressure drop (just looking at max flow or max head won't tell you what you need).
5. repeat steps 1-4 by adjusting nozzle size until you find something that works.


Volume is what will determine the distance with a given nozzle size. The pressure drop will be set by the design and the flow rate (friction in the line, losses at the nozzle, etc.). If I have some time later today, I will estimate the pressure drop. Do you know the diameter and length of hose from the pump to the cannon (also type of hose)?


EDIT: Here is what I came up with. This is the pressure drop for different nozzles at what I calculate for the minimum flow rate. These values assume that the pump is located 2m below the cannon and do not include the losses due to the hose. They do include pressure drop due to elevation change, acceleration, and the losses at the nozzle and at the sharp elbow at the inlet to the cannon. If you keep a small nozzle (and lower flow), the pressure drop is mostly due to elevation. It seems like if you use the 3mm nozzle, you will have the easiest time finding a pump that will work (1+ gpm at say 2.5 m head, higher numbers will work better). If you go to a larger nozzle, the pump will need more flow as well as head.

[TABLE="width: 379"]
[TR]
[TD]Nozzle Size (mm)[/TD]
[TD]min flow (gpm)[/TD]
[TD]min flow (lpm)[/TD]
[TD]dP (m)[/TD]
[/TR]
[TR]
[TD="align: right"]3[/TD]
[TD="align: right"]1.0[/TD]
[TD="align: right"]3.8[/TD]
[TD="align: right"]2.25045[/TD]
[/TR]
[TR]
[TD="align: right"]5[/TD]
[TD="align: right"]5.4[/TD]
[TD="align: right"]20.6[/TD]
[TD="align: right"]2.29762[/TD]
[/TR]
[TR]
[TD="align: right"]7[/TD]
[TD="align: right"]9.0[/TD]
[TD="align: right"]34.0[/TD]
[TD="align: right"]2.56335[/TD]
[/TR]
[TR]
[TD="align: right"]9[/TD]
[TD="align: right"]16.0[/TD]
[TD="align: right"]60.5[/TD]
[TD="align: right"]3.39408[/TD]
[/TR]
[TR]
[TD="align: right"]18[/TD]
[TD="align: right"]36.0[/TD]
[TD="align: right"]136.1[/TD]
[TD="align: right"]7.00267[/TD]
[/TR]
[/TABLE]
 
Last edited:
Today I got my 12 volt pump out and set it up with an inlet hose in a wash tub full of water. I set the pump on top of the truck so there was about 1.5 meters of lift. I used regular garden hose with a valve on the end of the outlet. I could get from 6 feet to 27 feet by adjusting the valve opening. I did have some collapse on the suction hose but it still worked. My pump has a pressure switch so it turns itself off when it builds up enough pressure when the valve is closed. When I allow it to build pressure and open the valve it gets the most distance. With the valve full open, about 12 mm it gets the shortest distance.

My pump is a 12 volt FLOJET Model 4300-504
13 amps
4.9 GPM / 18.5 LPM
Press 45 PSI / 3.1 Bar Max

http://www.pumpagents.com/FlojetPumps/4300-504.html

I use a 3/4 inch inline filter similar to the one in this link on the inlet side of the pump.

http://www.bing.com/images/search?q...EF9DE3C002296226134685E39&first=0&FORM=IDFRIR
 
Last edited:
Smooky said:
Today I got my 12 volt pump out and set it up with an inlet hose in a wash tub full of water. I set the pump on top of the truck so there was about 1.5 meters of lift. I used regular garden hose with a valve on the end of the outlet. I could get from 6 feet to 27 feet by adjusting the valve opening. I did have some collapse on the suction hose but it still worked. My pump has a pressure switch so it turns itself off when it builds up enough pressure when the valve is closed. When I allow it to build pressure and open the valve it gets the most distance. With the valve full open, about 12 mm it gets the shortest distance.

My pump is a 12 volt FLOJET Model 4300-504
13 amps
4.9 GPM / 18.5 LPM
Press 45 PSI / 3.1 Bar Max

http://www.pumpagents.com/FlojetPumps/4300-504.html

I use a 3/4 inch inline filter similar to the one in this link on the inlet side of the pump.

http://www.bing.com/images/search?q...EF9DE3C002296226134685E39&first=0&FORM=IDFRIR
Click to expand...


Sounds like fun.

I guess you could add a small tank using a pump like that so you would have a little reserve.
 
DonL said:
Sounds like a overkill to have some water fun.

snipped
Portable batteries that can give 230V are hard to find and would be very expensive if you did find one.
Click to expand...
Also, I would think that 230 Volts AC or DC would be very dangerous to use with a water toy.

I like regular pump up water canons, which do a good job and are cheap enough.


German and Swiss designers come up with fabulous equipment; I work for a Swiss company, but everything is always overkill, WHY????????????????? Like Don said
 
?ukas H?u?t?ler said:
Awesome man, thanks. So I'm thinking of getting a 58 gpm pump. As far as I've understood, this baby would have a head of 28,5 feet, ≈ 14,25 PSI. How come smaller pumps that do like 26 gpm can produce 135 feet of head ≈ 67 PSI? Because the tubes have a smaller diameter?
Which should I go by to estimate the power, i.e. the length and solidity of the water beam, the gpm or the PSI?

Thanks,

L
Click to expand...
Bring along an air pressurized tank with water in it. Oh yeah, they have small ones called water canons/super soakers
http://www.hasbro.com/nerf/en_US/supersoaker.cfm?s_kwcid=TC|1027471|water%20cannon%20toy||S|e|11722310094
 
nukeman said:
You will need more tha 5 gpm unless you go smaller on the nozzle. The volume needs goes as the square of the diameter. For instance, if you took my original calc and used say a 9mm nozzle, the reduction in volume would be (9/18)^2 = 0.25, so about 36 gpm*.25 = 9 gpm (plus additional to cover air resistance).

With a 7mm nozzle, the required volume is (7/18)^2 * 36 gpm = 5.444 gpm. Again, this is the minimum fllow required to get the distance.

The design of most things (like this) takes some iteration. In this case, it is like this:

1. pick a nozzle size (based on what is available or how wet you want to get them)
2. calulate the volume
3. calculate the pressure drop
4. look at pump curves to see if there is a pump available (consider price, power requirements, etc) that can meet the volume minimum at that pressure drop (just looking at max flow or max head won't tell you what you need).
5. repeat steps 1-4 by adjusting nozzle size until you find something that works.


Volume is what will determine the distance with a given nozzle size. The pressure drop will be set by the design and the flow rate (friction in the line, losses at the nozzle, etc.). If I have some time later today, I will estimate the pressure drop. Do you know the diameter and length of hose from the pump to the cannon (also type of hose)?


EDIT: Here is what I came up with. This is the pressure drop for different nozzles at what I calculate for the minimum flow rate. These values assume that the pump is located 2m below the cannon and do not include the losses due to the hose. They do include pressure drop due to elevation change, acceleration, and the losses at the nozzle and at the sharp elbow at the inlet to the cannon. If you keep a small nozzle (and lower flow), the pressure drop is mostly due to elevation. It seems like if you use the 3mm nozzle, you will have the easiest time finding a pump that will work (1+ gpm at say 2.5 m head, higher numbers will work better). If you go to a larger nozzle, the pump will need more flow as well as head.

[TABLE="width: 379"]
[TR]
[TD]Nozzle Size (mm)[/TD]
[TD]min flow (gpm)[/TD]
[TD]min flow (lpm)[/TD]
[TD]dP (m)[/TD]
[/TR]
[TR]
[TD="align: right"]3[/TD]
[TD="align: right"]1.0[/TD]
[TD="align: right"]3.8[/TD]
[TD="align: right"]2.25045[/TD]
[/TR]
[TR]
[TD="align: right"]5[/TD]
[TD="align: right"]5.4[/TD]
[TD="align: right"]20.6[/TD]
[TD="align: right"]2.29762[/TD]
[/TR]
[TR]
[TD="align: right"]7[/TD]
[TD="align: right"]9.0[/TD]
[TD="align: right"]34.0[/TD]
[TD="align: right"]2.56335[/TD]
[/TR]
[TR]
[TD="align: right"]9[/TD]
[TD="align: right"]16.0[/TD]
[TD="align: right"]60.5[/TD]
[TD="align: right"]3.39408[/TD]
[/TR]
[TR]
[TD="align: right"]18[/TD]
[TD="align: right"]36.0[/TD]
[TD="align: right"]136.1[/TD]
[TD="align: right"]7.00267[/TD]
[/TR]
[/TABLE]
Click to expand...

Wow, this is really great stuff man. So what is the dP exactly? Is the table based on the requirements to get the 4 m?
Thanks,
 
Last edited:
Sorry about that. dP is differential pressure (or head) that the pump has to work against. The real head will be a bit more because I didn't include the hose from the pump to the cannon, but that resistance may be small depending on flow. For instance, if you used the 3mm nozzle with 1gpm or so, you could likely neglect the loss in the hose (assuming it is a reasonable diamter (say 18mm) and not very long). If you used the 18 mm nozzle and needed 36+ gpm, then you would need to include the resistance of the hose and may need to go to a larger diameter hose (such as 25 mm) to keep the resistance reasonable.


It sounds like finding a 12v DC pump that would support the 5mm nozzle might be hard to find (or may usee too much power). I think that I would start with the 3mm nozzle and see how that works for you. I bet that you will find that a decent 12v pump with the nozzle will shoot well beyond 4m.

Here is what you do for the pump selection:

1. Based on the 3mm nozzle, we know that the pump needs to do at least 1gpm (~4 lpm) when working against a head of about 2.25m. So, we know that the max flow and head of the pump need to be higher than these values.

2. Ideally, you would look up the pump curve for the selected pump and see what the pump can actually flow at that head. For instance, say you found a pump that had a max flow of 8 l/min and a max head of 4m. Although both of those number are larger than the numbers listed above, you really need to check the pump curve to know. In this case, the max flow (8 l/min) is with 0 head. At 4m head, the flow is 0. The pump curve tells you at say 2.5m head, what the pump flow will actually be. If it is greater than 4 l/min, it is okay.

3. If you can't find a pump curve, you will still be okay if the max flow and max head are well above what you need. For instance, the pump that Smooky last posted (the one that he has) is 5gpm and 35 psi (roughly 65ft of head). Because both numbers are well above what you need (1gpm, 2.25m), we know that this pump would work without even looking at the pump curve. However, it is probably more powerful than you really need, but that isn't a problem except for cost.
 
nukeman said:
Sorry about that. dP is differential pressure (or head) that the pump has to work against. The real head will be a bit more because I didn't include the hose from the pump to the cannon, but that resistance may be small depending on flow. For instance, if you used the 3mm nozzle with 1gpm or so, you could likely neglect the loss in the hose (assuming it is a reasonable diamter (say 18mm) and not very long). If you used the 18 mm nozzle and needed 36+ gpm, then you would need to include the resistance of the hose and may need to go to a larger diameter hose (such as 25 mm) to keep the resistance reasonable.


It sounds like finding a 12v DC pump that would support the 5mm nozzle might be hard to find (or may usee too much power). I think that I would start with the 3mm nozzle and see how that works for you. I bet that you will find that a decent 12v pump with the nozzle will shoot well beyond 4m.

Here is what you do for the pump selection:

1. Based on the 3mm nozzle, we know that the pump needs to do at least 1gpm (~4 lpm) when working against a head of about 2.25m. So, we know that the max flow and head of the pump need to be higher than these values.

2. Ideally, you would look up the pump curve for the selected pump and see what the pump can actually flow at that head. For instance, say you found a pump that had a max flow of 8 l/min and a max head of 4m. Although both of those number are larger than the numbers listed above, you really need to check the pump curve to know. In this case, the max flow (8 l/min) is with 0 head. At 4m head, the flow is 0. The pump curve tells you at say 2.5m head, what the pump flow will actually be. If it is greater than 4 l/min, it is okay.

3. If you can't find a pump curve, you will still be okay if the max flow and max head are well above what you need. For instance, the pump that Smooky last posted (the one that he has) is 5gpm and 35 psi (roughly 65ft of head). Because both numbers are well above what you need (1gpm, 2.25m), we know that this pump would work without even looking at the pump curve. However, it is probably more powerful than you really need, but that isn't a problem except for cost.
Click to expand...

This is great info. I found this one: http://www.****.co.uk/itm/FLOJET-WA...tEquipment_Accessories_SM&hash=item4cf47691a0

(The **** represents the e bay, forum won't let me post it)

Specs:
Connections: - for 13mm (½") bore hose or Hep20 push-fit connectors CW193
Dimensions: - 208mm long, 160mm wide, 100mm high
Fuse Size: 10 amp
Output: 12.5 litres/minute (2.8 gallons/minute) open flow
PRESSURE SWITCH - cuts in at 1bar (15psi) - cuts out at 2.4bar (35psi)
Efficient, high-flow, self-priming pump serving 3 or more outlets
Multi-diaphragm design self primes to 1.5m vertical lift, can run dry without damage
Supplied with snap-in ports for hose or Hep20 connectors
Quiet running
Motor protected by automatic thermal overload cut-out
Built-in bypass valve eliminates the need for an accumulator tank

By reasonable diameter, do you mean that less than 18 mm would be too little and create too much resistance or the opposite? Maybe it's good to have at least 18 mm so that the hose fills the barrel as quickly as possible?

The description says "Multi-diaphragm design self primes to 1.5m vertical lift". Does this mean it's only got a head of 1,5m?

Thanks,
 
Last edited:
?ukas H?u?t?ler said:
This is great info. I found this one: http://www.****.co.uk/itm/FLOJET-WA...tEquipment_Accessories_SM&hash=item4cf47691a0

(The **** represents the e bay, forum won't let me post it)

Specs:
Connections: - for 13mm (½") bore hose or Hep20 push-fit connectors CW193
Dimensions: - 208mm long, 160mm wide, 100mm high
Fuse Size: 10 amp
Output: 12.5 litres/minute (2.8 gallons/minute) open flow
PRESSURE SWITCH - cuts in at 1bar (15psi) - cuts out at 2.4bar (35psi)
Efficient, high-flow, self-priming pump serving 3 or more outlets
Multi-diaphragm design self primes to 1.5m vertical lift, can run dry without damage
Supplied with snap-in ports for hose or Hep20 connectors
Quiet running
Motor protected by automatic thermal overload cut-out
Built-in bypass valve eliminates the need for an accumulator tank

By reasonable diameter, do you mean that less than 18 mm would be too little and create too much resistance or the opposite? Maybe it's good to have at least 18 mm so that the hose fills the barrel as quickly as possible?

The description says "Multi-diaphragm design self primes to 1.5m vertical lift". Does this mean it's only got a head of 1,5m?

Thanks,
Click to expand...
Lukas,
Last item means that it will only pull water up on the suction intake side 1.5 meters for self priming, but the discharge lift should only be limited by the motor hp, which will be building up the pressure higher as the height of the water collumn it develops will weigh more and more the higher it needs to be pumped up to. Your sketch above does not seem to be of much concern here. Your concern is that the pump should be located less than 1.5 meters above the surface of the water supply or the pump will not be able to self prime itself.
 
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