Flipper components

[maddox]

Flipper components

Geoff. These rules apply only to the storage bottles, not the buffertanks.

The buffertanks will not be charged outside the arena.
Also, the PRD mandatory in any pneumatic system will make sure the buffertanks, valves and rams are not pressurised above their rated working pressure.

Otherwise the system is not allowed.

[Mouldy]

Flipper components

8.1 = The bottle WAS storing butane, But the Butane would be removed to store the compressed air from the compressor.

8.2= impossible to get a compressor strong enough to go over 1000psi in a feather.

8.3= Myself and DTK used similar bottles no prob on 10bar (think DTK ran 16bar infact)

8.4= Its 10bar = 140psi. However I agree YES a 11bar PRV should be used. Also i dont believe a buffer tank has ever been required to have a Burst disc, Reseviours only i believe.

8.5= Dump valve, goes without saying.

8.6= please explain the need of an isolation valve for a LP buffer tank.

[jamesb]

Flipper components

from my point of view, having made only about 10 of these, the cheapest way to make a nice flipper is.....

£5 compressor. these get to anywhere between 100psi and 150psi before the pressure causes heat backup and the compressor cannot go any further with the pressure. it is in effect self regulating, crude, but it works.

to save more cost, trial and error at home with small diameter holes will limit pressure further, aim for 50psi to avoid the need for prds, although event organizers have been known to allow compressors without prds

pipe buffertank, a long coil of the pipe going to the ram acts as a buffertank, and is light, cheap and very effecive, as proven by whipper.

valve, a single acting valve is fine, easily picked up for £10, and will flow enough gas to make a nice flipper.

a cheap plastic ram from the £1 shop is a large diameter, long stroke solution, but having tested them dont go higher than 50psi. you have a ram alex, so no worries.

finally, bungee return, dont need an exhuaust valve if you have a leaky ram (like to £1 shop one) or drill a 1mm hole in the ram.

cheap, easy, and SAFE!!!

e-mail me for info, i have most of this in stock, and beware overly expensive advise. A lot of money is wasted in this sport following other people, when there are better/cheaper/simpler/safer ways of doing things.

[maddox]

Flipper components

oeps, double

(Message edited by maddox on February 26, 2006)

[jamesb]

Flipper components

and if i posted half the grief i get from people on msn for giving advice, this thread would be twice the size. Dont know why i bother half the time.

Just a reminder, if you dont have 10 years engineering experience, 5 years practical fighting robot experience, 9 GCSEs, & alevels, an HNC in health and safety, with NEBOSH certification, a degree in mechanical engineering, nearly 200 satified customers with over 50 machines built, a 100% safety record, £1,000,000 personal liability insurance against accidents, bad service, and advice, (and a lot more common sense than many of the people I know,) then please sit back down and dont snap at me on msn then log off so i cant reply.

end of rant.

[geoff]

Flipper components

Mario,
Forgive me if I have got this totaly wrong, as you know gas is not my strong point, but as I understand the situation after a chat I had with Mike Lambert as FRA Pneumatics rep. his view is that buffer tanks or any other part of the system opperating above 3.4 bar may in theory need to tested and certified.
(see below)

8.7.
All pneumatic components used with pressures greater than 50 psi (3.4 bar) must be rated / tested to at least the maximum pressure available in that part of the system.
You may be required to provide documentation / certification to support this.

(for example, could such doumentation / certification be provided for Davids empty butane bottle?)

[woody]

Flipper components

Copy and paste ...

As both butane and propane boil at relatively low temperatures, they exist in the gaseous state unless they are contained under pressure or are refrigerated. The boiling point of commercial butane at normal atmosphericpressure is about 30°F and that of commercial propane is about €”45°F. Both are therefore necessarily supplied under pressure in containers filled to about82€”90 per cent of their capacities. The storage pressure for liquid butane is about 25 Ib per square inch and that for liquid propane about 100

[grant_ploughbot]

Flipper components

his view is that buffer tanks or any other part of the system opperating above 3.4 bar may in theory need to tested and certified.

Does this mean they dont need to in the rules but theroeticaly there should be a rule about it?

I wouldnt have thought they would allow butane bottles to sell without a certification of some form?

I have seen loads of robots over the years using butane canisters fo buffers, and i dont think they were told to remove them? Not sure but i dont think so.

QUOTE-JB(and a lot more common sense than many of the people I know,)
Ouch JB, burning out a compressor every time its used? Wouldnt it be more sensible to invest a few pounds in a pressure switch to save buying a new compresser every fight?

**** If I was starting to build a new robot, I would be greatfull with help and guidlines on doing so, NOT Greatfull for people trying to push another idea to me, especially when it comes down to people putting personal coments on to pursuade me to to take their ideas because they either want recognition or money.

Im sure everybody can put down experiences, and some mch more outstanding ones! but thats not what advice is about, its to help others.
I would advise you away from CO2 to start with for obviouse safety reasons, but a setup like dave mentioned, they can be just as good fun.

Good Luck
Grant-Ploughbot

[grant_ploughbot]

Flipper components

Sorry,just read my post again, didnt mean it to sound asif it was purely aimed at anyone, but thats the general feeling you get when asking for advice here!

[woody]

Flipper components

his view is that buffer tanks or any other part of the system opperating above 3.4 bar may in theory need to tested and certified.

Does this mean they dont need to in the rules but theroeticaly there should be a rule about it?


All pneumatic components used with pressures greater than 50 psi (3.4 bar) MUST BE rated / tested to at least the maximum pressure available in that part of the system.
You may be required to provide documentation / certification to support this.

How is MUST BE an ambiguity?

[grant_ploughbot]

Flipper components

Arent they already tested though? one would have thought that being a highly explosive canister it wld have an even greater factor of safety than CO2 bottles? thus proving them safe?

I may wrong but its logical!

[maddox]

Flipper components

Geoff, As I mention in my previous posting. Everything working above 3.4 bar has to be pressure tested and certified. At least according to the prototype PID rules.

But buffertanks dont need seperate burstdisks, PRDs, or any other isolation device.

Grant, when you change anything to a pressure vessel, explosion hazard or not, it has to be retested. Even if the change is simply the orignal valve exchanged another one.

[grant_ploughbot]

Flipper components

Ah ok then. thanks mario.

[Mouldy]

Flipper components

Robots I€™ve seen with butane (or similar such as air horn) type bottles:

G3
Turbine3
DTK
Smash n grab

How many have been asked to prove the safety of there buffer tanks...none. but
just to keep you happy...

I€™ve tested a butane bottle up to 18bar, and for the 10 bar setup that was
required by the persons original question I believe a butane tank would be fine.
considering there€™s a 180% safety margin! and I believe only a 120% safety margin
is required.

James baker- were is the logic in putting a hole in your buffer tank or whatever
to use as a PRV?...I spent £12 on a compressor for my first feather weight...4
times...because they were of such bad quality they kept breaking. so a £5
compressor...you get what you pay for! And leaving it to burn itself out is a
good idea? how?

Geoffrey- Forgive me if I have got this totaly wrong, as you know gas is not my
strong point, but as I understand the situation after a chat I had with Mike
Lambert as FRA Pneumatics rep. his view is that buffer tanks or any other part
of the system opperating above 3.4 bar may in theory need to tested and
certified.

I believe Mikes team mates Feather DTK uses a tank VERY similar to the butane
bottles. So I very much doubt he would have a personal problem with these bottles. (sorry
if Im wrong Mike)

[ewan]

Flipper components

I personally think, only from what Ive seen, that pressure up to as much as 100psi on compressor systems should be allowed. The whole set-up looks really quite safe, obviously it depends whose hands its in... Can someone be very specific on the most prominent dangers of low pressure compressor systems?

Also, how does 12v the motor couple up to the compressor mechanism on most cheap units guys? Would it be easily feasable to change the motor?