lubricated pneumatics.

The rules are pretty clear with regard to not even inadvertently allowing air into hydraulic systems.

However, what about the reverse? Many pneumatic systems call for a lubricator; a very fine oil mister in effect, usually with a de-mister somewhere down the line.

I suspect I might want one; there are parts that may seize otherwise and it helps with cooling. It does nothing whatsoever to increase pressure and so has no safety implications so far as I can see, but wanted some feedback before I think more about it. :?:

There is nothing in the rules about lube, so no problem there.

According to me there is no need for a air-conditioning unit. The running time of our machines is a few hours at most. Imagine 20 testruns a year and 15 fights. Thats 3 hours total.
Lubing parts ain't nothing you can't do by hand when changing the CO2 bottles/charging the batteries/tightening the bolts.

I just use a tad of very light grease (or thick oil) to make the rams go easier. That only happens when I have the ram open for assembly or check-ups.
We did a test with a drop of paintball oil before every fight, but that wasn't a succes.

A key area where CO2 circuits differ from industrial or garage pneumatics is that they run much colder. When you first turn on the CO2 supply, the liquid CO2 boils at -57°C, which would make some lubricants turn into a wax, actually impeding the actions of valves, etc. Robots often end up internally like a scene from the South Pole after a bout, from all the frozen atmospheric moisture that collects on the pipework. So the recommendation of using paintball oil (paintball guns often run on CO2) or similar, is a sound one. One thing you will have to watch out for is the regulator or other moving parts in the CO2 circuit icing up, either stopping the weapon from working, or causing an unexpected rise in circuit pressure (that has happened to us before).

We have a car that runs on LPG, which has an evaporator that is heated by the radiator water to ensure that the LPG actually turns into a gas rather than entering the engine as a near-cryogenic liquid. If we had more time and resources, it would be tempting to build a heat exchanger round the motors to use their waste heat to warm up the CO2 to overcome the problems described above.

But your not allowed to heat your pneumatic system, I think that would count as a heat boaster.
The only thing you can do is put heatsinks on co2 bottles or pipes to help disipate the coldness or perhaps 'accidentally' run you pipes near the motors.

It's not a heater, it's a cooler, to keep the motors from melting.

Also, there isn't much to be "heated" by a good drivetrain.

Quote:

---

Originally Posted by Max

But your not allowed to heat your pneumatic system, I think that would count as a heat boaster.
The only thing you can do is put heatsinks on co2 bottles or pipes to help disipate the coldness or perhaps 'accidentally' run you pipes near the motors.

---

Or run the cold pipes round the motors in order to cool the motors :D
I don't think anyone would mind, if there were no actual boost to the system, other than keep it running at above freezing

Anway, looks like my lubricator would be ok then. At the moment, my mad experiment uses an onboard compressor (several in the final design, but just playing with one, for now) and these are what need lubricating. Currently trying a scroll compressor which normally compresses freon, not air. Hence the need for added lube.


Edit: Beat me to it, maddox

Be careful though. If water gets into the mechanism it becomes Carbon Hydroxide which is banned for not being inert

With Bacon Wizards compressor it's possible to have water build up due condensing. But to make from that carbon hydroxide, you'll need more than a bit of chemistry going on.

And water in CO2 setups. Ice on the outside , yes, but in the tanks, doubtfull.

Quote:

---

Originally Posted by psychostorm

Be careful though. If water gets into the mechanism it becomes Carbon Hydroxide which is banned for not being inert

---

Carbon Hydroxide is entirely hypothetical, so far as I know, and would form a highly unstable liquid. You cant ban something that has probably never been made outside of a Lab for fractions of a second.

What happens when you put a lot of CO2 in water? You get a fizzy drink....

In theory, you could have trapped moisture in a newly-built system from atmospheric humidity, but possibly not enough to cause a problem?

I would definitely like to find a way to prevent regulators icing up without contravening the rules. We had a regulator (not welding type but aluminium bodied one with sliding components) lock in the fully open position making our system pressure rise. On that occasion, oxide build-up on the inside due to a long period of disuse was a factor, but locking up due to differential contraction and lubricant thickening at the low temperature could still be a concern. Maybe the answer would be a large heatsink or a finned regulator body.

Is it possible to run an onboard compressor without discharging the batteries prematurely? When we first built Terminal Ferocity back in 1999 (a slower gentler era in Robot Wars), we have a petrol-powered chainsaw on top and did consider running a compressor using a belt drive off that, but ran out of space to put it in.

I have heard on a liquid-nitrogen powered robot in a non-fighting application before. I wonder if anyone has thought of using CO2 to provide the drive via a couple of air motors, as well as the weapon?

Its the Dihydrogen Monoxide you need to watch-out for. It's lethal stuff. I almost swallowed some inadvertently just earlier today :crazy:

Sorry, you're right. it's carbonic acid.

You may need to refer to the DHMO Safety Data Sheet: http://www.dhmo.org/msdsdhmo.html

Quote:

---

Originally Posted by JohnRyland

You may need to refer to the DHMO Safety Data Sheet: http://www.dhmo.org/msdsdhmo.html

---

Good advice for anyone... please read, folks. It may save your life.

For low temp lubrication either molycote or PTFE based lubricant should be OK for temperatures down to -73C

http://www.dowcorning.com/applicatio...t.aspx?R=387EN

I would say to use this stuff sparingly, As has been mentioned, the duty cycle of pneumatic systems on robots is particularly low, so in most cases I would say lubrication at service intervals is all you need.

Where I work we have valves that operate 30,000 times a day... Don't have them fail very often aslong as the air supply is dry... Occasionly they stick, put a bit of sewing machine oil or similar down the infeed pipe to lubricate the shuttle and there good for a while after.... You will never get to the point of having to do that kind of maintenance on a robots valve... You will blow it up or chop it in half years before its working life runs out.

Ah, yes I'm sure you're right. But it's not the valves I am worried about. I am running a low pressure system and I will be using plenty air-flow; maybe more than a cylinder will allow. Which lead me to look at compressors. I believe I could get somewhere using scroll compressors from car air-con, but they need lubrication.

If i can get away with it for 4-5 mins at a time without lube, then great, but I am very uncertain. I'll be able to do some tests in the next couple of weeks.

I'm using molykote 33 on mine, its good for very low temperatures, I still cant get your idea of using compressors rather than Co2 though.