Assorted Pneumatics Questions

Morning all.

Ive recently aquired a triplet (well, a pair and an odd one out) of smallish low pressure rams (along with a small freebie valve - cheers Simon :proud:).
Theyve been sat in a shed without the holes covered (so Im told) for a while, so theyll need to be stripped down, checked over, dried out and reassembled. I think I already know the answer to the question Im about to ask but still...

Should I just do as Ive said above - i.e. dry them out completely then reassemble them - or is there anything else that Ill need to do? For example - are there any bits that should be lubricated or WD40d before I put them back together? I know I need to get rid of the water (popular quote - CO2 and water dont mix - Ill take their word for it but I dont know why) but is oil similarly dangerous? I vaguely seem to remember something about a potential explosion risk with oil in pressurised CO2 tho I could be wrong.

One other question relating to the freebie valve - it currently has a sort of spring loaded roller arm on one end to actuate the valve itself. If I wanted to replace this with a solenoid - how would I go about it? Its a standard 5/3 jobby (I think - well, it has three ports on one side and two on the other) and its made by Norgren - has a little diagram on it with the ports numbered 1-5 and the ends (one end with arm thing and one with a plastic cap) numbered 12 and 14 I think.

OK next questions. Im considering starting out on 50psi with a small 12V compressor filling a buffertank (so the CO2 issues above arent immediately critical admittedly). Ive worked out that for the larger of the cylinders (50mm bore) I should get about 150lb of lift at the ram which is ample for now. However, Im not sure how to do the whole linkage thing. I have a small tank Id like to use (no pressure rating on it but its metal and itll be fine for 50psi) and I can work out the part where I drill out the valve at the top, braze in a piece of tube and tap a BSP fitting into it. However, how would I go about connecting the compressor to the circuit? Ive got a car style valve knocking around (and Im sure I could get more) but Im assuming that the adapter on the compressor wouldnt give a reliable enough connection - and then theres the issue of how Id get the valve into the tank in the first place (as they fit from the inside) so how are people currently doing this?

Also, if I buy a really cheap compressor Id need a 50psi relief valve to keep the pressure down - do these exist and does anyone know where I can get one?

Finally - Im intrigued by the RRC approach. How did they connect a plastic bottle to a pneumatic system via a valve? I didnt see the Real robots issues where they did the pneumatics so Im completely at a loss as to how it works. Was it a proper solenoid valve? Or was it all car style fittings and some sort of servo operated valve thing? And how did they modify the bike pump - if they did - to be used as a ram?

Thatll do for my current shotgun effect of questions for the moment although Im sure Ill be back with more.

Cheers all

-- Kev

A serious lot of questions.

Water and CO2 dont mix.. depends on what you want, a sodadrink, or a mixture that eats staal and ali like acid eats a piece of chalk.This is when lots of water ,and lots of CO2 are mixing.
Normaly, when those rams did stay in a shed, no real problem would occure.

And if the rams move freely, without any kinks,noises or resistance there isnt much reason to disassemble them.In this case, a little silicon greas-like molycote 111, doesnt hurt.

The valve, thats a cascade valve, or an old mechanical endstrokevalve(dont know the real UK names for those)To solenoid that you will have to chjange the endcap and things like that.The easier way is to use a servo to press in the lever.Oh, and it is probably a 5/2 valve.

For pressure relief valve and compressor shut off system, mail paul Cooper. he has all you need for that kind of system.Its better to shut off the compressor than to vent pressure.

And, to be funny, I have a setup, with everything attached ,even a small 5/2 valve with solenoid.Ready to be build in, mail me if you want a piccy of it.
Also, I have a larger article written on recycling low pressure rams.

Cant help you with the RRC questions.

Mario,

Cheers for all that.

a mixture that eats steel and ali like acid eats a piece of chalk.
Id like to see that :proud: But I digress.

The larger ram (the one thats currently in bits) moves nice and smoothly and is all very clean except for a tiny bit of rust residue around the rubber part of the rod, and a coinciding mark (smooth) around the inside of the cylinder. The smaller ones are smoothish in motion, but move much more freely in a central 30mm section or so - I assume this is down to the adjustable damping which Ive had a play with, so it sounds like Im onto a good thing with them.

I would be interested in seeing a pic of your compressor setup - Ill send you a private with my email address on it. I think I already have the article on recycling rams now you come to mention it - Ill dig it out and have a look.

Its better to shut off the compressor than to vent pressure.
Thats what Im thinking, although the cheapest compressor I can find with this ability is £20, and its possible to find much cheaper variants without the auto shut off. Ill likely end up with the £20 one. Im just thinking from a spares point of view - Id sooner buy two at £7 each than two at £20 each.

Ill have a play with the valve and a servo although it takes a fair bit of force to push so Im not sure how well my standard servos will do.

OK - now to grease the one I have disassembled (and maybe the others if I can be bothered) - whats the best way to do this? Smear it on the rubber plunger and run it back and forth a few times? Or try to rub it directly on the inside of the tube?

Cheers again

-- Kev

p.s. If anyone else does know about RRC or even entered with a Rexs Robot style plywood flipper then Id be interested to know how it works.

kev - the RRC robot used a pair of servos that crushed some thin pipe as a makeshift valve.

but if you want a cheap valve (sorry if your not after this sort of info i havent read all of your post) try a duster handle from a air duster/gurney. they work quite well

Oh and while I remember - Mario your article mentions a significant weight saving to be had with the rod part of a cylinder - what does this entail?

Cheers

-- Kev

carbonic acid

carbonic acid, H2CO3, a weak dibasic acid formed when carbon dioxide dissolves in water; it exists only in solution.
Carbonic acid forms carbonate and bicarbonate (or acid carbonate) salts.
It contributes to the sharp taste of carbonated beverages.

In Turbine 3 I used a Pressure switch to operate a relay that switched of the compressor...the pressure switches are adaptable from pressures. I set mine to turn the compressor of when it reached 10bar...worked great. Mario now has my pressure switch so he can make further comments as he knows how they work etc.

As Glen said the RRC valve was basically 2 servos that squished pipes to vent and open ports to and from a ram. My first valve was even cheaper than that and worked alot better and only took 1 r/x channel...Carnt remeber the link but somthing like http://www.mutre.co.ukwww.mutre.co.uk *shrug* Small medical valve glued to a servo....They also sell the bottle caps to fit onto coke bottles were u can slide some nylon pipe on...nice little toys witch only cost a few pence. Have fun:).

Dave moulds
Team Turbine

What should I use to set up a LP CO2 flipper? Right now I use compressed air and a 25mm diameter * 75mm stroke ram. Latter I would like to upgrade to a 63mm dia * 100mm ram.

Would a 3.5 oz bottle be big enough?

What valve would you recomend?

Are paintball gun regulators the best to go for?

What volume buffer tank would I need?

We can get the same brands in Australia as you can. Any advice you care to give would be appreciated.

Philip Taylor

Ah nuts, Philip, why do you have to go a bigger flipper :sad: I found it bad enough the last time T2M did a 360 barrel roll in mid air beofre hitting the ground! Why do you have to start getting me really worried :sad:

Wanna try and put the flipper into Annihilations spinning bar again :proud:

Yes I do.

What size buffer - You need atleast 3X the volume of the rams in a robot...industry use 5x but 3 is enough for a robot.

What valve = Bigger is always better in turbulence I have a highflow valve that came from EWE 2..Flowrate even went as big as to use a 1/2 valve in a feather.

Reg...umm Woody would be best to answer that?

what size bottle = Most people in the UK use 600g of co2 witch should last 5mins easily.

Dave moulds
Team Turbine

lol, after looking at todays Marauder battling video, it seems Philip has temporarily mount a 5L pressure pump tank onto the top of Marauder and is using his 600g aluminium tank as a buffer :proud: Definately looks funny with this 5L tank mounted on the top of the robot :proud:

Thank you, Dave.

I would like to use a 3*2 spring return valve. What does everyone think is the best choice there? I have read that some 1/4 valves have the same flow rate and pressure drop as 1/2 valves. Would anyone care to comment?

Thankyou for your help

Philip Taylor

And one more question that recently occurred to me : If I use a compressor system at higher than 50psi, Im assuming Ill need to get my buffer etc certified (or find one that already is), but what about the pressure relief valve? If I just stick a 10bar PRV somewhere in the circuit would that comply with the rules?

Thanks

-- Kev

p.s. Oh and does anyone have any LP bits (not rams unless theyre very cheap but anything else) theyre trying to offload? Cheers.

Can I use soda stream bottles on their side? I havent used CO2 before. I will regulate the pressure to 10 bar.I have read that with other bottles you would normally put in a dip tube into the top gas filled part of the bottle. I would need to have the soda stream bottle positioned on its side. Would that be an issue? How would I solve any problems this may cause?

You should at least angle the bottle so that the valve is higher than the base .....say 15 degrees?

Thanks, Woody. I will look at the shape again.

What happens when the robot is upside down? The regulator would be getting liquid CO2. What does this do to the reg?

It freezes up the reg. It takes some time before the reg will function properly again. A solution is to stick a coil of thin copper tube (large surface arena etc) between the bottle and the reg. That tends to give the CO2 enough opportunity to change state into a gas.

Thanks alot Eddie. Has anyone tried the expantion chambers that they use for paint ball guns to stop the regs from freazing?

Note: SOME regs will happily cope with liquid.

I suspect that almost anything you can think of has been tried... :)

Does anyone know where I can get a 1.1kg fire extinguisher from? If not, any size under 2kg would be acceptable.

Cheers,

Dave

I can supply 1 ali 1.1 kg Project II bottle, or an brand new 1.5 kg bottle , with the same dimensions, unfortunatly, that 1.5 kg bottle is a steel one.

But why such a big bottle for a featherweight? the cheaper, lighter and simpler solution is to use 1 or 2 20 oz paintball bottles.

Mario. Thanks for the info. What are the dimensions of the 1.1kg Project II bottle, and what size connections and on/off knob does it have please?

Cheers,

Dave

The connection is the classic 5/8 UNF 18tpi CO2 attachment. Size, 101mm diameter and total length 420mm. The Knob is a small 5 lobbed round one, diameter about 50mm. Way to big for a feather. Even the ali one weights over 1.8 kg.

Also, I was intending to use this as the bottle for the resurected Project II. Combined with the basic cost, and the P&P, it is more intersting to buy one in the UK. Dont forget Im over the channel.

http://www.justpaintball.co.uk/acatalog/Co2_Systems_.htmlhttp://www.justpaintball.co.uk/acata..._Systems_.html

20 oz = 0.56 kg ....You may well find ...as Mario says .... these more suitable for a feather.
Internal thread ...5/8 UNF...Tap/Valve thread 1/2 BSP.

http://www.p8ntonline.com/product.asp?P_ID=246&strPageHistory=search&strKeyw ords=co2&numPageStartPosition=1&strSearchCriteria= any&PT_ID=allhttp://www.p8ntonline.com/product.as...ch&strKeywords =co2&numPageStartPosition=1&strSearchCriteria=any& PT_ID=all

This bottle has HSE approval.