Pneumatic

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.

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.

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.

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.

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...

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.

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

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?

As the current FRA rule set stands Stealth appears illegal on 2 points ........a seperate shut off valve and a low pressure PRD ......with the possibility of a 3rd infringement with the vent valve rating.

8.6.
Gas cylinders that do not incorporate a valve (for example: the gas is released as soon as the cylinder is screwed into it€™s mating pneumatic connection) such as found on disposable welding bottles and €˜fizzy drinks€™ machines must have an additional remote isolation valve accessible from outside of the robot.

And
8.8.
A certified pressure relief device [PRD] must be installed in each part of the pneumatics system where a different operating pressure is used (operating pressures separated by a pressure regulating device).

So it needs to be argued that the additional remote isolation valve isnt needed in this instance.

A PRD is in my opinion a must .......it isnt possible to quantify a bit of low pressure rubber tube that will rupture @ ??!!** psi as a safety device.

If it had a Low Pressure PRD and a vent valve to match the PRDs rating ....Id be happy with it.

Woody

Edit
It should be possible to combine the function of pressure dump valve ...... in the unlikely event of the flipper being locked down ... with the vent valve IF it has a manual overide.

(Message edited by woody on September 21, 2006)

I dont think you have ever seen a Sodastream bottle - It screws in to a fitting yes, but it also has a release valve built in to the tank. In Stealth the valve in the bottle is the firing mechanism and everything past the valve is vented and low pressure. Fitting a second valve after the tank makes the system LESS safe as there is now a section of pressurised tube between the tank and the valve.

In this bot, there is also a dump valve just before the ram that is open at all times other than during the firing cycle; it opens to retact the ram and stays open until the next firing. I believe it failsafes open by spring tension.

I dont think you have ever seen a Sodastream bottle ........

Who is the you in that sentence?


(Message edited by woody on September 21, 2006)

Err, obviously that would be Woody? Im not saying that tanks like those refered to in rule 8.6 dont exist, but the tank in Stealth does have a valve and so 8.6 cant really apply.

Nick ....Perhaps I can interest you in a visit to one of my webpages ?
http://www.teamonslaught.fsnet.co.uk/co2_info.htmhttp://www.teamonslaught.fsnet.co.uk/co2_info.htm



(Message edited by woody on September 21, 2006)

The original valve in a sodastream bottle is a pin valve. Turn the bottle into the socket and the valve opens.

If something is wrong then, it will go wrong with the hand in the robot. If a seperate isolation valve is used this risk a lot less. Especialy the screw valves we recomend have the advantage that you can open the system very gentle.

Nick, Woody was using sodastream bottles in the earliest days of Robot wars, and probably before. This means at least 10 year of experience.

There are many people on this forum who have an enormous amount of experience with pneumatics. You read the name and you know that you can respect the information they give. It does take some time to learn who you can trust.

A seperate manual valve is essential for pin valve bottles.

Not only does it make the system safer for arming, but pin valves often freeze open. A manual valve means the bottle can be isolated and safely removed.

@ Nick .....
Ill try and explain my earlier post.

As the current FRA rule set stands Stealth +1>appears illegal on 2 points

Im fairly sure that rule 8.6 is applicable to Sodastream bottles with pin valves and should perhaps have the addition of ..... see words in red.

8.6.
Gas cylinders that do not incorporate a hand operated valve (for example: the gas is released as soon as the cylinder is screwed into it€™s mating pneumatic connection) such as found on disposable welding bottles and €˜fizzy drinks€™ machines must have an additional remote isolation valve accessible from outside of the robot.

So it needs to be argued that the additional remote isolation valve isnt needed in this instance.

The basis for this is .. as you pointed out ... the gas isnt released as soon as the cylinder is screwed into it€™s mating pneumatic connection.

My finishing line of that post....before the additional edit ...

If it had a Low Pressure PRD and a vent valve to match the PRDs rating ....Id be happy with it.

I must point out that I have NO official standing in the FRA.

Regards Woody

A soda stream, and most, if not all legal CO2 (and N2O) bottles have a burst disk, rated at +/- 200 bar- except for older bottles, who can have lower rated burst disks at 135 bar.
If you can get 70 bar/1000 psi burst disks to replace the 200 bar ones, these will be accepted as a PRD in the FRA rules (as far as I understand). Problem is, once it goes, say bye bye to all the CO2 on board.

Using a rubber tube with a estimated burst pressure around 1000 psi is not accepted.

Hey mario...
After talking with you last night I started to look for 1000psi burst disk which I cant find. Well, not one that is not MASSIVE and heavy... You or Woody know where I can find one?

Hmmmmm what about this?
http://www.mcmaster.comwww.mcmaster.com part# 5825T218 that would let me bleed the air in the system and act as my 1000PSI PRD.... Yes, No, Maybe?.?.?

But again, if anyody has a link to a 1/8 NPT relief valve that would be even better!

This is the last thing I need to figure out before I make a large order :)

Rocket is coming... Muwahahahaha :-D

(Message edited by wazio on January 17, 2007)

Chad, I searched for a 1000psi bust disk myself, and found a firm willing to make a minimum of a 1000 at $6 each.

Its easier and cheaper for me to order normal PRDs in germany and adjust them for FP use.

Those are 1/8 bsp- easely adapted to 1/8 npt

Sorry to ask yet again... But how do I figure out the hight of the flip?
:-p
Thanks Mario!!!

Quick and rough calc for guesstimating the potential throw of a ram .

Swept area of cylinder in cubic inches multiplied by the pressure in psi.

Divide this by the weight to be thrown in lbs and then halve the result to account for inefficiency.

So for a 2 bore x 2 stroke we get a swept area of 6.28 cubic inches
multiply that by your pressure of ~750 psi.

That gives us 4,710 lb ins .... divide that by the weight to be thrown..... in your case 30lbs .....this gives us 157 inches of potential throw.

Divide that by the inefficiency factor and we get 78.5 inches or 6.5 feet of throw.

Chad - Try the hassocks calculator. Its proven accurate for me.

http://www.hassockshog.co.uk/flipper_calculator.htmhttp://www.hassockshog.co.uk/flipper_calculator.htm

I have been doing a little work on a new ant while parts are getting made for the FP bot. I thought you would get a kick out of this so here is a link to some info and pictures about it.

-http://www.teamwazio.com/bots/getflippen.phphttp://www.teamwazio.com/bots/getflippen.php

In testing I have tossed another ant about 2 so I am rather happy. I cant expect much out of a 1pound bot.

I am currently getting parts for the FP bot which will be done for RG. I got the 42mm drive units from BaneBots that look really nice. I will add them into the CAD soon. I just need to get a little jet time in then the main parts will be done. A new CAD shot is on my profile. I also addd a hard stop to the arm incase the cord breaks.

The new web site is up and running. Take a peek and check it out. http://www.teamwazio.comhttp://www.teamwazio.com

i very much like that flipper!

Go Pookie!!! :)

Ill make sure i make the blue kevlar/carbon shell when ill Brads green one. Epoxy Time!

(Message edited by cavecrusher on January 24, 2007)

Getflippen looks way cool. And GetRDone makes even more noise then my ant. :)

@tim: perfect steenkolen-engels. :)

aight! :P

Awesome bots Chad! I really like Rocket and Get R Done. :)

Thanks guys! Should have Get Flippen driving today and Get R Done #2 totally done too.

My bot Apogee is now spinning. Take a peek at the video page.
http://www.teamwazio.com/bots/apogee.phphttp://www.teamwazio.com/bots/apogee.php

One word:

Sweet!! :proud:

Woah !
I love the BROOOOOM!! noise in the first video :P

F**k that for a game!!
I know a thing or two about spinners and that thing needs to be locked up!! (That is one SERIOUS robot!!)
Seriously for a moment though Chad, I hope that.. 1) it was well attached to the bench and 2) You were at a safe distance...(like in the next state!!)

NICE!! (Is it going to San Fran in June??..I would love to see that run in anger!)

Ya, it was clamped to the bench well and I had my cam sitting on something while I was on the other side of the shop. Tiz the first robot that I have been scared of :).... And yep, RoboGames will be its first event. I will have the whole Wazio fleet there, I will be rather busy! Next up after the flipper is a real walking 3lb bot. Hope to see a bunch of ya at the event! Anybody who comes gets a Wazio shirt for maken the trip.

I want a spinner like that one.... The sound is like Malankaia Baba Yaga gone bad on steroids