Compressor Saftey

FRA rule 8.3.:
The compressed gas shall be stored in a comercially manufactured gas cylinder of appropriate design, specification, and certification. Except where the maximum storage pressure is less than 50psi (3.4Bar).

This raises another question- in the origional Cassius, Rex used an F1 role bar as the basis of the chassis, but also stored 100psi CO2 in there for the suspension. It had no problems containing that pressure (it was thick, high grade steel), and Im sure the whole system would have been implimented safely. Would it still be outlawes under these rules, or is there room for negotiation on this issue- i.e to ask the EO prior to the comp?

hum... we need to test these coke bottles as I have always worked to 300psi.

So with a couple of reasonable sized bottles I imagine you could get a comparable number of same-powered flips as someone on CO2. Or I spose you could use a 500ml bottle as a 10bar buffer tank - that would save some weight.

Id be tempted by FP tho as regulators are expensive :proud:

-- Kev

so are two burkets! id prefer to pay 15 quid for a reg, instead of 140quid for a pair of valves!

Coke bottles would be excellent, cheap, high capacity, large orifice buffers. Still the concept of using soft drinks bottles to stored high pressure CO2 is quite a worrying one on the face of it. Some official input would be much appreciated :-)

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

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

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

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

All I have to say is BANG!

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.