Compressor Saftey

[jim]

Compressor Saftey

...preferably before I shell out £60 on a new buffer tank!

[m2xt]

Compressor Saftey

Neil, you only need a PRV with a compressor system if the remaining pressure fittings etc. are rated lower than the maximum potential pressure from the compressor. As for pneumatic connections, it always remains a possibility that nylon tubing etc. can blow off. The safety related consequence of such a failure in the arena is minimal. The risk of personal injury does exist if such a failure should occur during testing / maintenance of the bot - safe working methods should always be adopted. You are encouraged to ensure your build quality is adequate for the purpose, if you bodge the connections, you may still fail a tech check.

James, you are permitted to use non-certified components on systems with pressures up to 50 psi. This rule was included so as not to exclude bots built to Rexs Robot Challenge rules. Above 50 psi, the pneumatic rules apply and that means your coke bottle has to be certified. However, I would suggest to event organisers that coke bottles used at pressures above 50 psi would not be acceptable for a number of reasons. There are no CO2 bottles listed unlike the Mentorn rules, what is required is a suitable vessel in terms of design, specification and certification.

Eddy, yes the Cassius approach is almost certainly unacceptable as the FRA rules require all pneumatic components to be adequately protected within the body shell.

Paul
FRA Techical Team

[stu]

Compressor Saftey

From what i herd, Coke bottles can only take up to around 100psi before they go bang BIG TIME. I wouldnt go too high in coke bottle. Maybe 80spi, sometimes 100psi, ive found all coke bottles differ, even tho there all created the same way.

Mr Stu

[team_ireland]

Compressor Saftey

Its quite funny to watch the robot arm pouring liquid co2 into a coke bottle.

All I have to say is BANG!

[big_nipper]

Compressor Saftey

Are coke bottles tested at time of manufacture. I would guess at yes even if its just for a leak test. If you could find out the test pressure then under the rules (As I see them) they would be acceptable if derated by 20% from the test pressure. You would of course have to be able to provide documentation for it. Anyone out there work in a coke bottle manufacturing plant? Personally I wont use them as they are too easily damaged and the dry powder fire extingusher bottles dont weight that much anyway.

[blazerbotics]

Compressor Saftey

weve taken them to about 110psi, and ran away cos it was getting very hot.

[maddox]

Compressor Saftey

Im testing cokebottles, the 1.5L trow away versions, and they seem very happy with 70 psi.

I would suggest the RRC rule of 50 psi... oh, the FRA did cover that already.
Ok back to square one. Like the original posting told, the FRA rules seem to be very safe.Adhere to them.

[Mouldy]

Compressor Saftey

I used to run a small coke bottle on 80psi, no problems...Even ran 1 on 100psi once...not at an event though, incase someone found out But it worked well and Ive tested a 2littre coke bottle to the bursting point...sort of. I got it up to about 200psi. Scary...The problem is not usually the bottle itself, but the thread on the end or inside the caps stripping.

But Id always suggest a blowtorch bottle as an upgrade from a coke bottle!

Regards
Dave moulds
Team Turbine

[nmx6000]

Compressor Saftey

Im not sure what pressure the compressor will run to before it stalls the motor but I believe it will be over the 10 bar so I will fit the relief valve to be safe. Thanks everyone for all your advice with some luck and even more hard work I will be at preston on the 29th! cheers

[kaideejee]

Compressor Saftey

Anyone know how much it would cost to get a modified blowtorch type O2 bottle certified to use as a 10 bar buffer?

-- Kev

[tim_jones]

Compressor Saftey

Our coke bottle testing concluded that if pumping air (as opposed to CO2) there was no bang, the plastic heated and expanded until it quite quietly and undramatically released its contents at around about 200psi. Quite an anti climax when youre wearing ear defenders and cowering in the adjoining room!

The only problem I would envisage would be how to find a use for a holey plastic bottle that had formed itself to the shape of the inside of your robot

Tim

[jamesb]

Compressor Saftey

Got it!

been asking all my old rc plane mates about this, and Ive found my 300psi figure.

Apparently, the old cylindrical 3 litre coke bottles were ok to 300psi. This was not the case for the smaller bottles, infact, the sculped 1 litre version blew up at half this according to the bloke I was talking to.

So how does he know? he tested them a few years ago, whacked them on a standard test rib and noted them all down.
He currenly uses a 3 litre coke bottle at 300psi in his quad pulsejet powered Vulcan.

there we go, I knew Id heard 300 somewhere.
as for the rest, Id reccommend we look at the coke bottle issue, with possibly more tests, as 50psi was there for rex, whats the difference with 70psi, or 80? if it saves money and is safe why no go for it?

[stu]

Compressor Saftey

I think coke bottles at 80psi should be alright.

Mr Stu

[m2xt]

Compressor Saftey

First 80 psi then 100 psi and then 150 psi then what?

Fizzy bottles were not designed for anything other than to contain fizzy drinks. Are we to type test every fizzy drink bottle on the shelves of Tescos? Their manufacturing properties will differ as will their burst pressure. Their burst pressure will vary with temperature (hot air from that little car tyre compressor), how do you monitor fatigue? If you crease the plastic by accident as a vented bottle is rather weak, should it be rejected? There are just too many variables with fizzy bottles for me to feel confortable using them at pressures above 50 psi.

Keep the fizzy bottles to the RRC bots, there are other more suitable alternatives for the bigger boys wanting higher pressure.

Paul
FRA Technical Team

[stu]

Compressor Saftey

Fair Enough - safest bet.

Mr Stu