Here is a thread for Soda Stream discussions.

Should we modify the rules to allow the use of soda stream bottles? (with appropriate precautions for safety etc)

Aaron mentioned they were banned in the UK/US rules because its illegal to refill them yourself.

I think that is valid, though in a robot like Stealth where you might use one tank per EVENT the $11 a bottle price is pretty nice compared to buying your own refill gear.

Plus it means every event you get a brand new tested safe full bottle.


Anyway thoughts opinions and ideas!

I have not seen the setup, but this is what woody wrote about it in the uk forum:

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"appears to use a Sodastream bottle and the standard push valve actuated by a spring return car door actuator / solenoid...the high pressure gas is quick shot vented into a ram the expanding gas pushes the ram open till the vent holes placed high on the cylinder wall are exposed releasing the gas..... a bit like a pressure relief valve. "

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I think not, which is a problem for some of us and a proposed rule change. There might be problems if the flipper was fired when it couldn't possibly extend and vent - like being stuck under the arena wall. The system would remain under pressure and might be dangerous to handle.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Well, that is the ram acting as a pressure relief valve at full extension yes.

Also in Stealth's case there was rubber tubing in the low pressure section that would burst if the ram was stuck down and the co2 valve stuck open.

So yes, that system has two non traditional pressure release valves.

People are probably not going to be happy with non-traditional pressure relief, particularly the exploding tubing. I trust Dumhead's engineering excellence, but how do you prove the tubing will burst a t aparticular safe pressure? Also, how do you relieve pressure if the system gets jammed in the closed position but the tubing doesn't burst? It would be good if the system had a manual emergency relief valve that could be operated externally. As I understand it, a pressure relief device like a burst disk will only operate if the pressure is excessive, not when the pressure is within limits but the system is stuck in an active & pressurised state.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

I agree, in Stealths case Andrew tested it pretty extensively and was able to convince the EO's that it was safe, but that doesnt work for everyone.

If any co2 robot gets jammed with a pressurised system then you have to be able to release that pressure. Of course if moving the robot might make it fire the ram etc then it does not matter what type of valve you have, its unsafe to get near it.

Its not practical to be able to vent the gas from the outside of the robot manually as far as i can see, but in a case where it is possible to get to a valveit is just as easy to say cut the rubber tube as it is to turn a valve etc. In fact I would cut the tube with a knife on a pole and feel a lot lot safer being further away from the robot and having a lower pressure system in use!

The UK guys must have gotten a solution to this ages ago - I would think about a re-usable spring loaded pressure reliefe valve that protests against over pressure situations (like the sodastream releases too much gas) and can be manually operated from outside the bot, possibly withthat long pole.

Just had a thought: if the system is fired and the ram is jammed so the gas can't vent, wouldn't a second firing in the jammed position be sure to burst the tube and vent the system? That would work for me if it was tested beforehand. For the traditionalists, adding a fairly cheap burst valve would do exactly the same thing.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

i dont see how pressure could exceed the rated limit causing the pressure valve to open unless the temperature went way up (i think that causes pressure to rise in the tank?), or if the system was fired, then something forced the cylinder back closed which would not happen in a mis-firing and that seems to be the only reason a pressure relief there would be used.

or so i would think?
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In our systems it pretty easy and not as expensive as some people tend to believe. We have small pressure relief valve that pop open as soon as pressure builds up to high, and clase as soon as pressure is below the treshold again. In events were it is very hot you can sometimes hear that, because you get a distinct popping noise out of the robot.

besides that a valve is required that will blow off any gas that might be left in a pressurised system. This valve should be accessible from the outside without tools.

is this the correct idea on the system of stealth then?

If Stealth was jammed and under pressure the quickest way to fix it would be to give it a kick and move it away from the jam. The ram would extend, vent the pressure, and if the valve was still open for some reason it would keep venting all the gas out.

Personally I find the idea of manual shutoff valves and mechanical over pressure valves to be a bit stupid. There's no way I'd be crouching over a pressurised CO2 bot to operate the manual shut off or purge valve!

quote:

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Also, how do you relieve pressure if the system gets jammed in the closed position but the tubing doesn't burst? It would be good if the system had a manual emergency relief valve that could be operated externally. As I understand it, a pressure relief device like a burst disk will only operate if the pressure is excessive, not when the pressure is within limits but the system is stuck in an active & pressurised state.

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quote:

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Originally posted by leo-rcc:

is this the correct idea on the system of stealth then?

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The difference between a spinner running down an the gas leaking out of your ram is that we can't SEE the gas leaking the system might still be pressurised when you think it is safe. I didn't know you had a relief valve in the line - does it failsafe to the open position? If so, you probably have more safety measures than most of the traditional bots. you could just turn your radio off to release pressure and a power loss would do the same.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

yeah there's a vent solenoid which is what allowed the ram to retract.
It was powered at all times except when flipping, so unless multiple physical pneumatic failures occurred as well as a loss of power it would vent.

There's also a cutoff switch that turns the gas valve off before the ram reaches full extension.

Did I mention it's a pretty safe setup? (as far as CO2 systems go anyway!)

You can't see the gas leaking out, but you can certainly hear it quite well - and it'll be pretty obvious when there's a potential problem, because the bot would have to have been reduced to a rather shredded pile of metal!

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the system might still be pressurised when you think it is safe.

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Have you ever locked the flipper arm in the half way up position and pressurized the system to 1300 psi? If so, which part blows first and at what pressure?

BTW I think that innovation is great. We all just want to make sure that the risks involved in our sport are managed.
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So even the rain that falls isn't actually going to fill our dams and our river systems

So Stealth in an open system, but only after the valve? But you are classing the whole system as being open because the valve is so close to the supply tank. The proposed rule "changes" that are being discused state that no manual shut off valve, purge valve or over-pressure devices are needed between the valve and the ram. But these where never needed in the rules anyway.
The rules are that a correctly rated manual shut-off valve, system purge valve and an appropriate over-pressure safety device (eg. burst disc) are needed in the normaly pressurised areas of the system. Since you would have to be realy stupid not to have your ram vent after being fired (it would never return) then all pneumatic robots I have seen to date would be classed under your rules as "open".
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