Water cannon

Would look to fire suppression equipment specifically for a fire boat.

Try checking some information with fire boats. They are using water cannons that might be similar for what you want.

Thanks guys.

I did try to look for info on those type of pumps and how they are driven, but I couldn't find any technical information. Those boats appear to be a way overkill as far as water pressure.

-Mike

Hey Mike, sounds like its more for show than go. Are these fired in sequence, simultaneous or running continuously.

I would think the people who design the "dancing" foutains are more likely to be using the techniques and technology you are looking for. Fountains being essentially a public focus item, the designers are usually more than willing to brag about their design and innovation.

There will be from 1 to 20 working at one time. I'll keep the fountain poeple in mind.

Thanks,

-Mike

20 cannons on a boat. Thank God you did not ask for cannon balls.

You've to be specific & detailed. You've not mentioned size of bore of cannon.

I might be wrong but a little guessing goes a long way:

I presume what you need is a Booster Pump System. Your length is 40 yds works out 132 ft + 15%= 152 ft = 4.5 bar.The pump cannot be selected without the flow details. The pumps to be ss 316L from Groundfos . The system is like this. Suppose you need 140 m3/hr. So you install 3 pumps in parallel 50 m3/hr with head 166 ft/5 bar.

Each pump to have a pressure switch and outlet disk check valve. All outlets tapped into main outlet pipe . The outlet pipe goes to a pressure vessel (partially filled with nitrogen gas). A main lines comes out of the vessel and distrubutes to each cannon with a solenoid valve at inlet of each cannon.The first pump pressure swich set at 4.8 bar , the second at 4.6 bar and the third at 4.5 bar. Each pump starts & stops with flow Vs set pressure of pressure switch. At inlet solenoid valve to be with on/off switch to fire at will.

The Boosting system comes complete and I suggest you check this at sites of KSB pumps/Gould/Wier/Grundfos - who again will ask you "flow".( I just buy pumps and make my own pressure Vessel since the bigger the vessel the longer the pump on/off or standby time).Select a pump with in-built inverters.

We do similar system of pressurized water distribution to textile machines/ Tannery drums where the minimum water pressure requirement is 3.5 bar ( Not viable to build an overhead tank that high)So our batteries of pump with inverters work with flow & pressure requirements.

This is a personal experience. you got to check yours.

For the size and bore I don't have any specifics yet because they are not built yet. I was imagining a 3/8 opening at the tip.

-Mike

Where on earth are these 40 cannons pointing? Are they all firing symultaneously?

Action and reaction are equal and opposite! Yer gonna have one danged fast marine craft! ( or is that the aim....)

As per

Dvader1000

You need to know your required volumetric flow rate and output pressure first.

We know the ouput pressure the volumetric flow is only required.

Dvader1000

"Also, are you going to pump water into a tank in the hold, and then pump the water to your cannons from the tank? "

No the pump outlet line will go straight to supplying to all the cannons with a vertical line tee-ing off into the pressure vessel. The water will be pressurized.

Dvader1000

"If so, you'll need 2 pumps at least, one to fill your tank and one to supply your cannons. "

You need 2 pumps only 1 . If one pump is sufficient the other is stand-by or 2. If one pump cannot handle the load the pressure drop is registered and the second pressure switch starts this pump.

Dvader1000

"If not, then how is the water going to be supplied to a pump? By a ram scoop? You'll need to decide all these first first before you can consider what type of pump to use."

A 3" ss 316L pipe maybe 6' in length will be tee-ing into the pump(s) inlet ,closed at one end. The other end a flexible hose with a foot check valve (long enough to reach from the boat to the water) to do the suction.

Sorry this reply was with reference to No. 7 Not No.5.

The pressure and flow is what I don't know. How do I firgure that out????

-Mike

The Navy will mistake him as an enemy and fire their guns to blast him off before he does any damage with his 40 cannons.

Hey Wrenched -- It's 20 cannons to shoot 40 yards -- but even with 20 cannons the reaction should be very powerful, as you said.

I wasn't thinking they would be THAT powerfull. Just more powerfull than 20 garden hoses.

-Mike

You need to know your required volumetric flow rate and output pressure first. Then, after calculating your pressure losses, you will be able to size your pump. From the flow rate, you will also be able to size your pipelines. Also, are you going to pump water into a tank in the hold, and then pump the water to your cannons from the tank? If so, you'll need 2 pumps at least, one to fill your tank and one to supply your cannons. If not, then how is the water going to be supplied to a pump? By a ram scoop? You'll need to decide all these first first before you can consider what type of pump to use.

Read No:10. With due respect.

You can use eiheim water pumps! These are used for heavy duty salt water aquariums! You can find these with various capacities from Eiheim pump manufacturers.Tese are salt water resistant! Then there are the CV Kettle pumps made of stainless steel and are sea-water resistant! Sucess!

I have a couple of pumps you can have. What psi and gpm dp you require?

I wish I knew. That is the main question I am hoping someone can help me answer.

-Mike

You may want to try asking The Fountain People in San Marcos Texas.

I can offer two sites that I know of. www.elkhartbrass.com and www.akronbrass.com

Both of these companies have very detailed flow charts in their catalogs. I believe it is available on line. They deal with fire products. That translates to high price along with high reliability. Brass pumps should work well for your needs. If the water is fairly debris free you can use a suction from the bottom of the boat. Two recommendations for your consideration. 1) Oversize the suction inlet and strainer. 2) oversize the pump and use an adjustable relief valve to dump excess pressure back to suction, or to the body of water you are floating in.

Now if you make a connection in the suction side, and connect to an overhead container of dish washing soap, you can hide yourself in the foam. Good luck.

While you are hunting for specifics for pumps, energy sources, flow rates etc, why not take a simple tank, something like 1 foot in diameter x 5 to 6 feet long, solder 40 3/8-inch common hose couplings onto the tank, and run 40 short ganden hoses from the "manifold". This will give you an idea of what you're up against and some feel for the volume and pressure of the water. You might be able to hire yourself out, on completion of the boat, as a fireboat!

That's not a bad idea. It sounds like I may have to do that. I was hoping that there were some type of calculations I could do to get close to what was needed before I start building a prototype.

-Mike

You are very very close.

1 . You have a water boosting system for the 20/40 cannons.

2 . You have the 40 yds / 5 Bar Pressure.

3 . you have a solenoid valve at each inlet of the cannon with a switch .

( You need 20 people to stadyby each switch to switch on each cannon/ you play along with switches by bringing all the wires to a panel of 20 lights with switches to switch on by one man. This is irrelevent now and the panel guy can play along to operate single/ multiple solenoids/cannons together or with time laspe with a timer).

4 . What you presently lack is flow gpm?

suppose you want 50 gpm, this becomes 50 x 20 = 100 Gpm pump at 5 bar

for 40 cannons 200 Gpm. You can select one big pump or set of pumps 25 Gpm/50 Gpm/75 Gpm etc.

Now tell me - What are the cannons for? To put out fire? To scare fishes? To display fancy fountains on floating boat? To ward off Tax Guys? To sink surfers? To shoot pirates on sufboards?

50 x 20 = 1000 gpm

At those figures you will need a BIG pump, powered by a big motor, or smaller flow rates.

Here is a start for you.

1/2" nozzle at 80 psi (5.5 bar) should reach 37 meters, and flow 66 gpm (250 lpm)

66 gpm times 20 = 1320 gpm

7/8" nozzle at 50 psi (3.5 bar) should reach 40 meters, and flow 201 gpm (761 lpm)

201 gpm times 20 = 4000gpm

Above nozzles were at 32* above horizontal.

These formulas may help you

Solid Bore Diameter Formula:

GPM= 29.71 x Dia. sq x square root of nozzle pressure.

Solid Bore Reaction Formula:

Nozzle Reaction= 1.5 x diameter x nozzle pressure

Note: Nozzle pressure is measured with a pitot tube. Don't confuse nozzle pressure and pump pressure. They may not be the same.

Great bob c ? Where were you hiding for so long?

He has to tell where he wants to use the 20/40 cannons?

If he wants to fight fire its a different senerio and the immense quantity of water flow will be justified to work on. There is another thing requiring consideration - Kwh power.

This too need to be generated with a diesel generator on board.

The cost/Kwh on 20 or 40 cannons for what purpose needs to be justified.

A good figure to start with would be 75 horsepower to run 1000 gpm at 50 psi.

If he is able to get the nozzle size lower, he will cut gpm drastically. His requirements are on the low end of the charts I have. BUT, I believe that he can drop nozzle size down to around .250 and raise the psi to 75 and have a reasonable combination. He is not fighting fires on water from only 40 meters. I believe this is to be a children's play device. If the discharge rate is kept low, electric switched water valves are plentiful in 12 volt dc. Higher water flows will also make aiming harder for children to control. Reaction force climbs faster with volume than it does with psi. It may help to work hard on very smooth nozzles to keep the stream together for longer distance without using higher psi. Less chance of hurting children.

Maybe, I missed something but I never did figure out what the purpose of these cannon are.

These are going to be mounted on a "pirate boat". And a kids are going to use them to shoot at another "attacking" boat.

-Mike

well I guess that rules out gas powered pressure washers... in that case i would keep a couple of old water fire extinguishers handy "to repell boarders, matey"

Mike, just an idea...

I don't have the complete scope of your project but instead of going for 20 cannons at a time, why not limit it to say, 5 cannons at a time (sequencing between the 20 cannons) for a 3 seconds burst (or similar). The controls would be fairly simple and you could greatly reduce the pump size needed.

-Rick

You have a very good idea. If you use a time delay to alter the discharge valve, you can use a smaller (cheaper) water system. Example; 1) The child pushes the discharge button, 2) Time delay only allows discharge valve to activate for 3 seconds, and will not allow the discharge valve to activate again till the valve has been off for 3 seconds.

The normal action of the children will take the 20 cannons out of sequence soon enough, and only 10 cannons will fire at the same time. What the child would see is a cannon that fires instantly, but only for 3 seconds. When he releases the trigger for three seconds the cannon will fire again for three seconds. Even if all of the children were to squeeze the trigger at the same time, all that would happen would be that the water pressure would drop off and the distance would drop off.

The time delay relays are way cheaper than the double water pump and engine.

hey, how about a catapult for lobing water balloons (trash bags) to mimic a deck mortar?

7/8" nozzle at 50 psi (3.5 bar) should reach 40 meters, and flow 201 gpm (761 lpm)

201 gpm times 20 = 4000gpm . To continue further with bob c's :

Simple centrifugal pump selected: KSB 80-20, size 4" x 3" CI pump , 2850 Rpm, 30Hp, 500 Igpm at 140 ft head(4 Bar) x 8 nos (4000 IGpm)+ 1 standby = 9 Pumps.

You can go for bigger capacity pump to reduce pump quantity in event you want to shoot all 20 cannons at one time. The combination gives you the advantage of any set of cannons from 2 thru 20.

(a ss multistage variable drive with energy efficiency motor can be 15 Hp-20Hp. economical in power usage saving in the long run. Flow in Ipgm which will be 10% + to above if Us gpm )

Install the pumps in parallel with inlet/outlet valves, inlet strainer, outlet disk check valve, on/off pressure controller with a boosting systems.Inlet/outlet header manifold 8" main, supply to each cannon 2" with inlet valve & solenoid valve.

Idea - You can market fire fighting boats in developing countries and even without asking bob c you can make bob c & mayself as 25% each partners.

How do you calculate going from a large diameter to a small diameter the GPM and PSI. A basic example: a 4" hose going to a 1" hose to the nozzle. What is the GPM & PSI in the 4" & then what is it in the 1" hose?

-Mike

The answer to this question is long and involved. In the design that has been talked about, the discharge rate is going to be the determining factor for all calculations. As an example, A water pump that can produce 1000 gpm. being discharged through a 1" nozzle would not be practical because the pressure required to flow 1000 gpm through 1" would be in the area of 500psi. And that would be way to high. Likewise a 100gpm pump will have less than 20psi through that same 1" nozzle. Have you found a discharge flow rate that will give you the reach you want combined with number of discharge nozzles you want? Here is the basic formula for flow.

GPM=29.71 x Dsquare x square root of NP

When GPM=Gallons Per Minute

29.71=Constant

d=Diameter of nozzle orifice (inches)

NP=Nozzle Pressure (psi) measured by pitot tube and gauge

I have a page from the Elkhart Brass Catalog that I will try to scan and post.

This equation looks very similar to the Fire Hydrant Flow Test formula. The only difference is that you have not included a coefficient of discharge (usually ranges from 0.7 to 0.9 depending on the geometry of the nozzle). Information below, sorry about the picture quality.