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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

How do i get a air tank to my launcher ?

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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thampson
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Re: How do i get a air tank to my launcher ?

Post by thampson » Thu Feb 10, 2011 6:09 am

Basrockets,

Air hoses usually have 2 ratings, one is the working pressure, the other is the burst pressure. For example, the high pressure hose we use has a working pressure of 290psi and a burst pressure of 1160psi. The air hoses also have an expected working life, and the more you use it over the working pressure the shorter the projected life of the hose.

You should probably check if the hose you are using has a working or burst pressure of 160psi. If your hose has a burst pressure of 160psi then the working pressure may be as low as 100psi (typical workshop air hose) which means you may be stressing the hose over its working pressure a lot of the time, which will lead to a failure.

Also the hose is not the only place you may get a failure, the types of clamps you use can fail as well as the types of fittings you use and how well you secure them. For the small investment of a few bricks and a bag of cable ties ie: $6 you are mitigating injury to yourself and spectators in the case of a failure.

Seems like a good investment to me .... :) TC:

-todd-


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guy97
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Re: How do i get a air tank to my launcher ?

Post by guy97 » Thu Feb 10, 2011 6:12 am

Hi thampson,
I think the guy said it was 160 bar hose

Regards,
Mathew



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thampson
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Re: How do i get a air tank to my launcher ?

Post by thampson » Thu Feb 10, 2011 10:13 am

Mathew,

Ah yes, you are right .. my mistake :)

Id say that would be the burst pressure then. Although its still connected to the launcher with a $2 clamp so they do still break. I think the sentiments are the same though, its still a very low cost method to mitigate the risk of getting hit with a flying hose.

:)

-todd-


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Re: How do i get a air tank to my launcher ?

Post by U.S. Water Rockets1 » Sat Feb 12, 2011 11:15 pm

ninja_iga wrote:Todd

good idea ! although the idea of carrying bricks.. haha tiring!
Instead of bringing bricks along you could just bring along water jugs with handles filled with water and string the hose through the handles and those can function as weights. When you are finished for the day, you can dump the water out and you carry the light empty jugs back home.


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Re: How do i get a air tank to my launcher ?

Post by ninja_iga » Sun Feb 13, 2011 3:49 am

U.S. Water Rockets1 wrote:
Instead of bringing bricks along you could just bring along water jugs with handles filled with water and string the hose through the handles and those can function as weights. When you are finished for the day, you can dump the water out and you carry the light empty jugs back home.
a much better idea!


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Re: How do i get a air tank to my launcher ?

Post by air.command » Sun Feb 13, 2011 6:36 am

If your hose is otherwise rated for the pressure (as it should be) it is unlikely to burst, the only problem then is if the end of the hose comes off the fitting. Why not just use a piece of string with one end tied a few inches from the end of the hose and the other end tied to the launcher? That way if the end of the hose comes off the fitting then it doesn't whip around. No need to carry any bricks or water jugs to the launch site. You can do this at both ends of the hose. You can use a cable tie like Todd uses or a hose clamp to stop the string from slipping off the hose.


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Re: How do i get a air tank to my launcher ?

Post by thampson » Sun Feb 13, 2011 8:54 am

USWaterRockets,
thanks for the suggestion, I thought of using 3L milk (empty) containers as brick substitutes but the plastic they are made of here is thin and soft and I was afraid the cable ties would just rip straight through it. Some tougher containers might be a good option though :)

George,
Thats a good idea to tie the hose at the launcher and the pump. Maybe a fishing wire trace with its clip on connections might work as well.

http://www.river2sea.com.au/img/product ... re_lge.jpg

I fear I may have hijacked this thread ... HJ: , however I think that discussion on this subject is worthwhile, there are some good ideas already to improve safety which others can benefit from.

For work I go to a lot of customer sites, some of them heavy industrial and I have sat through many OH&S inductions. The 5 minute risk assessment (Take 5) that a lot of client use is a wise investment when applied to our hobby. Its quite simple, take 5 minutes to survey the work (hobby) area and look for hazards and see what the risks of injury are and what could potentially go wrong, then what can be done to mitigate (reduce) those risk.

I did this 5 minute risk assessment when I was doing the 180psi hydro test of the 3 bottle stack and decided the risk of an untested hose / fitting at this pressure flying off causing injury was too high for my liking and devised the brick method to control a loose hose.

For any high pressure hydro tests or launches (over 120psi or so) I will be using the hose containment method (brick, wire trace or variation thereof) to mitigate the risk of injury due to a flying hose. Its really a very low cost to implement and only a couple of more minutes in setup time.

-todd-


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