Relief's in place of burst disc's?

[maddox]

The fire extinguisher valves Simon is talking about are the ones leaving this house. 2 seperate valves, mounted o,n an ali plate, with a servo to push them. It is perfectly possible to fit the PRD on the burst disk seat. No sensible restiction is applicable.
Just the best place, no need for extra T pieces or couplings to leak.

[simon]

Hi Mario, not seen you on-line in a while. Thanks for explaining something I seemed to be struggleing with

[evristow]

First of all, sorry for resurrecting this topic. I know this is an old discussion, but I do have a doubt that fits here, let me explain.

I recently moved from Brazil, were I was team RioBotz (Touro, some of you might know) captain. Since robot combat is highly addictive I decided to build a new robot to compete here in the UK, in Brazil and USA, at the Robogames. The only common class among these locations is 30Lbs Featherweight, and since the distances involved are huge, there wouldn't be any reason to build a heavyweight (We already have Touro Maximus in the US).

The problem:

I am designing a full pressure CO2 flipper, and read all the forum topics (really it took me months to do so) and rules, which by the way is really good concerning pneumatics. Researching about SPRVs I came across the Wizard of NOS valve (factory setted to 1000PSI), witch is intended to replace burst discs on NO2 bottles and one thing that always scared me was the possibility, even tough minimum, of a burst disc failure, such as presented in the following link:

http://forum.nitrous-advice.org/view...t=4025&start=0

When burst discs fail the whole content of the bottle is released, producing a dangerous situation if the bottle is being handled at the time, that can result in severe cold burns. I know that burst discs rarely fail, but they aren't fail proof, specially on an aggressive environment, such as combat arenas.

So the question is, can this specific valve be used in place of a burst disc?

If negative, can it be used at all?

I've already talked with Dave Calkins (Robogames Chairman) and Paulo Lenz (RoboCore Brazil Chairman) about the project and both gave me their blessing, although I will have to fit a gauge to compete overseas... Useless, I know, but it is the only point of the RFL rule that I failed to convince them.

Regards,
Eduardo Ristow

[kane]

Sorry I've only just seen this post!

It's a good question. The bottle burst disc is a saftey device made to prevent over pressure from rupturing the bottle. As illustrated in your example, the disc will rupture and vent the entire bottle in the event of over pressure.

A pressure relief device will open whenever the pressure exceeds a set level. In an enclosed space this may be a safety benefit, however experience shows that burst discs rarely fail and normally only when the bottle pressure has been exceeded due to overfilling. Although unlikely, a pressure relief device could also freeze potentially leading to a hazardous situation. Whereas a burst disc has no moving parts so is less likely to fail in a combat environment and if so, safely.

Bottles should be handled wearing gloves to prevent the risk of burns especially as the bottles themselves can freeze.

[maddox10]

A burst disk on the certified CO2 bottles are rated at least 135 bar, or in most cases 195 bar, because most bottles are rated at 200 bar work pressure.

For a burst disk to fail, as Kane writes, something has to be done very wrong. Overfilling and/or heating the bottle as main reasons. It has been known to happen, even in the pits. But except the noise and a large cloud of white smoke nothing else happened. The worst case I can imagine (oeps, had that happen, but not trough a failed burst disk, but by an used,but not empty extinguisher that started to roll in the trunk), is that a burst disk fails in a bloody hot car, and filling that car with chilly white smoke, making it impossible to see the road and other trafic participants.

The agressive enviroment of the Robot Arena's ain't the issue. If a bottle gets damaged in the fight, it should be discarded and replaced after that fight. If the valve is damaged, you cannot replace it at the venue, unless you have a full rig to test and recertify that bottle.