Pneumatic

[maddox]

Ok, here are some proposed rule changes to make
These rules apply to all open system robots. Closed system robots use the standard FRA or RFL rules.

Just to kick things of
-- Standard UN modified Soda stream bottles and valves and flow restrictors containing no more than the maximum rated weight of gas.

Legal and FRA regulations already make this mandatory. Also, overfill your bottles in a warm enviroment and the mandatory burst disk will make sure that all the CO will be vented in the air. And users of other gasses, the 70 bar/1000 psi Pressure Release Device makes sure the system cant be overpressurized.
Also, what is a modified soda stream bottle? A sodastream with another valve? As long the adapted bottle carries a valid certificate, everything is covered in the rules.


--The ram must have exhaust ports of XX area so at the normal working extension as assembled in the bot the ports are below the piston and can therefore vent the gas.

If somebody wants to build a 1 shot ram or a stroke and powerlimited ram, why not? This is not a safety issue with a good build ram.


--The ram must be locked in the extended position whenever the gas bottle is fitted. It makes no difference if the bottle is full or empty. Apart from when it is in the arena. Or EO designated test area.

Try this with a 250 kg Bungee wrap to retract the arm.... Or in a machine that used a double acting ram, with the downstroke as powerstroke(Terrorhurtz anyone)


--A suitable low pressure blow off device, e.g. vac hose or spring-loaded valve installed at inlet of ram.

What is low pressure,and what is high pressure? In any case, again a FRA rule in use. The pneumatic and hydraulic systems have to be equipped with a Pressure Release Device rated at the lowest pressure rating of the lowest rated components.


--Damage to CO2 bottle as for closed system rules.

Damaged gasbottles are no longer to be used. This is in the FRA rules, and a legal issue.

--Mounting of CO2 bottle as for closed system rules.

If somebody wants to mount a CO2 bottle with gaffa tape, who cares?

---Electric operated CO2 valve must be spring loaded in off position .

Why? What does this mean? This means no standard pneumatic valve can be used.


In short, I dont see any reason to accept these rules.
For me, they are or redundant to the FRA rules, or just a load of crock.}

Stealth ... whose pneumatic system appears to have spawned these questions .... 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.

One of the questions appear to be .....should the Sodastream IN THIS SYSTEM have an additional h.p. shut off valve ..... remembering that there is to all intents and purposes little or no pressure anywhere in the system @ rest.



(Message edited by woody on September 20, 2006)

(Message edited by woody on September 20, 2006)

Yes. Absolutely.

[overkill]

Why, exactly? the sodastream bottle has its own rated valve and (in this particular bot) the rest of the gas system is no pressurised except when its fired - an extra valve afterthe sodastream valve isnt helping safety in this case, just adding cost, weight and complexity.

[leorcc]

If your ram get wedged in because of a bent arm or for whatever reason not being able to extend properly, the system is not not pressurised anymore. I would definately demand have some kind of PRD fitted between ram and flipper.

[kane]

Only if the bottle cant be easily removed without tools.

Otherwise there is no way to make the robot safe. E.g. manually shut off the gas (so it cannot be electrically operated.

[overkill]

Wasnt the call for a shut-off valve, not pressure relief? I fully agree that a PRD is needed if the system cannot vent naturally...

[Mouldy]

Way i see it, all systems need to do the following things:

The main reseviour(s) must be certified for over there normal use and MUST have an acceptable burst disc attached.

Easy access to an on/off valve perminatly ATTACHED to the bottle.

Pressure relief valves for FP robots must be fitted before the valve that operates the ram. Low pressure machines idealy should have a Full pressure relief valve fitted on the High pressure side of the regulator and a Low pressure relief fitted to the low pressure output of the regulator (or as close to the regulation point as possible)

Dump valve. (bleeds the hole system down after a fight) If the main reseviour tank shut of valve is broken it can easily dump ALL the gas in the entire robot.

Locking pins- i believe all rams must be locked in the exstended possition. Then if the ram were to fire its not going to lift far enough to be dangerous. Also works for retract, the locking bar must be able to withstand the crushing forces of the ram.

I see no problems or dangerous loop wholes in the current FRA build rules for pneumatics, there sensible and safe.


The idea of having the vent at the top of the ram, i dont like, i agree with the what if the arm got jammed half open comment fully.

[woody]

Info on Stealth.
http://andrew.driftpig.com/robot.htmlhttp://andrew.driftpig.com/robot.html

[leorcc]

Well after getting better explenations as the ones i got in the beginning of the threads, and some pictures (thank you woody) on the uk forum, I am satisfied that a system like Stealths sodastream is as safe if not safer then regular co2 systems.

However, there have to be better guidelines than the ones ive read in the uk and this forum, maybe even a seperate soda stream system topic in the FRA rules. That way we all have some framework to start with when i have to tech-check a robot using a system similar to this one.

Robotbuilders have always looked for the boundries of the rules, and a new approuch is always encouraged, but it should be substanciated by a ruleset and not by the guy knows what he is doing. Of course that is a factor, but not measurable on the table.

So can someone have a swing at a rule-set we can all live with?