Flammable Gasses?

MikeVDS · Post by **MikeVDS** » Wed Jan 31, 2007 6:34 pm

Anyone know of some gasses that are still gas at normal earth temperatures (120 to -20 F ...ish) and compressed to 3000psi. Oh yeah and they should be flammable.

Post by **mdmf007** » Wed Jan 31, 2007 7:38 pm

Mike

heres some gases we use in the shop.

Acetelyne - Acetylene will decompose and explode violently at pressures between 100 and 200 kPa (15 and 30 PSI). It must be stabilized with acetone.

Methane - decomposes between 300 and 600psi
Odourless, colourless and non-toxic. Stenched for detection.
LEL 5%; UEL 15%.
Less dense than air.
Burns with a pale blue faintly luminous flame.

Hydrogen
Odourless, colourless and non-toxic.
LEL 4%; UEL75%.
Absolute combustion in a 1" (~25 mm) pipe is 4 km/s. - thats a supersonic explosion - wellpast the threshhold for what is considered a high explosive!!!
Much lighter than air and will collect at the highest point in any enclosed space unless ventilated.
Pale blue flame and almost invisible.
Plumb hoses in refridgeration-grade copper, stainless 316, barstock brass (milled not cast).

Mike Looking through my Marks reference book, I found no flammable gas that is stable and will not spontaneously decompose (explode) at 3000#s. Highest I found was methane at 600 at the high end.

I would double check the MSDS for the list some would include:
Acetelyne
Mapp
Hydrogen
Methane
Butane
Butalyene
LPG

later all

Tiahaar · Post by **Tiahaar** » Wed Jan 31, 2007 10:57 pm

Interesting stuff...does it have to be able to be stored at 3000psi?

Before anyone says "oxygen" please bear this in mind...from wikipedia in this case: "...Highly concentrated sources of oxygen promote rapid combustion and therefore are fire and explosion hazards in the presence of fuels. Oxygen itself is not the fuel, but as a reactant, concentrated oxygen may allow combustion to proceed dangerously rapidly."

There are some pyrophoric gases used in the industry I'm in, silane for instance, but at way less than 3000psi.

gyre · Post by **gyre** » Thu Feb 01, 2007 12:42 am

What the hell kind of shops are you guys using all that in?
Mixing hydrogen and oxygen together has a lively effect and burns clean.
Don't try that at home, kids.

Does it have to be a gas?

MikeVDS · Post by **MikeVDS** » Thu Feb 01, 2007 6:40 am

The 3000 psi is to store more potential energy to use it to turn a turbine. Lower PSI means more or large tanks for similar range. The idea is to run off of air, but with flammable gasses that could be replaced I could use expelled gasses to create flame effects. (not only from through the turbine but also pneumatic cylinders etc). I considered using an oxygen rich "air" and have a separate propane tank with lit torches. When the O2 hits them, it would create larger flames.

Tiahaar · Post by **Tiahaar** » Sat Feb 03, 2007 10:06 pm

MikeVDS wrote:The 3000 psi is to store more potential energy to use it to turn a turbine.

Hey Mike what are you finding out on this? Over on another thread where I was looking at flamethrower info buckethead alien was mentioning he was looking into using CNG and that it was stored at 3000psi...posibilities?
http://eplaya.burningman.org/viewtopic. ... c&start=40

MikeVDS · Post by **MikeVDS** » Sun Feb 04, 2007 9:57 am

Thanks. I'll look into that. I had thought it went into a liquid form at lower pressures, like propane, but I could be wrong. I was actually under the impression that propane was one of the many forms of CNG, but as you see I don't know much about the subject. Too bad to didn't get the job a while ago with the gas company. Maybe that's why.

phil · Post by **phil** » Sun Feb 04, 2007 11:29 am

Is this where someone pops in and says if you're more specific about what your looking for, you might get more help? :->

MikeVDS · Post by **MikeVDS** » Sun Feb 04, 2007 12:45 pm

More specific about what? If you want to help with the design of my vehicle, it's more than welcome, but I think I defined the details I need in a gas pretty well. At the moment it's still a thought project, but possibly something for 08.

I'm basically running compressed gas through a turbine and pistons to create motion that will be used for the vehicle. It will be a relatively light weight, one person vehicle, consisting of mostly just a frame and mounts for the drive system. Initial calculations are being done assuming an ideal gas pressurized to about 3000 psi (for tank sizes, energy calcs, parts, etc). Low pressure gas will be expelled from the system. A flammable gas could be ignited to use for flame effects which are timed with pistons closing or using other mechanical controls.

I figure by using a flammable gas I would not have to worry about a separate system to create flame effects. It's also a bit more elegant. Another restraint I'm putting on myself is using all mechanical and pneumatic controls (no computers or electronic controls). I'm usually a computer guy but I've been working with a lot of old pneumatic systems recently and I thought it would be a fun project. Also more elegant in some ways. I have yet to design the drive system, which will not be axial. The vehicle will be a walker of some sort, probably based off of 4-bar mechanisms. Turbine driven seems to be the most efficient though I'd like to work some piston driven components, just because I want to, but I need to figure out a clever way of doing it that makes it a worthwhile design decision. Which I guess is another arbitrary constraint I'm putting on myself at the moment.

If anyone is a big nerd and wants to put in some design contributions I'd love to talk, or wants to put in some money since I have 0 allocated to the project so far. I'd love a titanium frame if you've got the bucks but I'm not even considering exotic materials in the design at the moment.

gyre · Post by **gyre** » Sun Feb 04, 2007 1:41 pm

Titanium would be very retro.
How about boron-aluminum?
Murder on cutting tools though.

MikeVDS · Post by **MikeVDS** » Sun Feb 04, 2007 1:49 pm

Either way, more expensive than steel. If I ever finish a design that I'm happy with and it makes it to the top of my project list, I think I'll be building it on the cheap. Some of the controls I'm looking at are already quite expensive. It'll probably be a $4000 project if I can scrounge up a lot of the basic materials. I'm guessing at the moment based of a hydraulic robot I made. Right now I'm designing around self funded. Structural stuff can be altered last minute if something pans out for using alternative materials.

Stainless is heavy but it would look cool.

Tiahaar · Post by **Tiahaar** » Sun Feb 04, 2007 11:09 pm

very cool sounding vehicle! Here's some bits dug up on Wiki:

"CNG compared to LNG and LPG:
CNG is often confused with LNG. While both are stored forms of natural gas, the key difference is that CNG is in compressed form, while LNG is in liquified form. CNG has a lower cost of production and storage compared to LNG as it does not require an expensive cooling process and cryogenic tanks. CNG requires a much larger volume to store the same mass of natural gas and the use of very high pressures (3000 to 4000 lbf/inÂ² , or 205 to 275 bar).

CNG is also often confused with LPG, which is a compressed blend of propane (C3H8) and butane (C4H10)."

So anybody work for the Gas Company? What pressure does natural gas arrive at your home meter and what pressure does it leave the regulator for inside the home use?

I once drove a fleet vehicle that started on gasoline and then ran on compressed natural gas (CNG). It was a tad less zippy on the CNG, and an attendant had to do the refueling for you.

spectabillis · Post by **spectabillis** » Sun Feb 04, 2007 11:11 pm

so this is going to be compressed gas that provides power by releasing it to atmospheric pressure to drive a turbine? or is this flammable gas being ignited to provide thrust?

just started a project that might share a thing or two in common, dont know. but mine is a surprise so i dont want to comment openly just yet. but what robot did you build before? and what camp are you going to be in?

Post by **mdmf007** » Tue Feb 06, 2007 9:20 am

Tiaharr -
Gas arriving at your home is at about .25 (1/4) PSI on discharge side of the meter, and at about 25 pounds at the street

later

MikeVDS · Post by **MikeVDS** » Tue Feb 06, 2007 9:39 am

It provides power by releasing it to atmospheric pressure. I've always had ideas for running a small vehicle off of compressed air. You can do some good regenerative breaking with this idea too.

I've done quite a few energy calculations and you this ideas is quite feasible. I read that some company in the UK is selling golf carts that run off of compressed air now too. I'm not sure if they use regenerative breaking.

I've done a few robots for Battlebots. I'd like to bring one to the playa which still needs some work and never quite realized it's potential. It was a 450lb hydraulic/8 HP combustion driven monster. Sitting in my friends garage still. So I got a good idea on pricing of pneumatic and hydraulic parts (since we considered pneumatics as an alternative to hydraulics). I thought it would be fun to drive around on as an art car, though there would be a few bugs to work out. I have pictures but can't access them from this computer.

This year our camp will be the Tiki Fuckos http://tikifuckos.org. It'll be a new theme camp that should continue on for at least a few years. We're going to be part of Gigsville Village and camped with/next to the Sandcrawler camp again, which wasn't much of a theme camp but brought the Jawa Sandcrawler in 06. As mentioned before I'm not working on this year and getting this camp together and all of it's projects suck up all my time.

If you want some input on any ideas you have I'd be happy to give some feedback. I often have time to do thought projects while driving, waiting, etc.

spectabillis · Post by **spectabillis** » Tue Feb 06, 2007 12:51 pm

reason i asked about camps, i sometimes guage the number of people and interest in having a robotic-insanefuckingmachines collective camp. just curious.

got most of my project figured out, but pneumatic drives are interesting. will look up regenerative breaking.

EspressoDude · Post by **EspressoDude** » Tue Feb 06, 2007 2:12 pm

Pneumatic systems are not very efficient. If you have used an air compressor and air powered motorized tools, you will be familiar with the heat generated at the compressor head, and the cold and often ice formed on pneumatic tools. This is wasted energy. I would guess effieciencies around 20 -25% But no MOOP. Hydraulics are closer to 70+ % efficient, but HUGE MOOP potential.

If you want to check out the regenerative stopping, you want to look for regenerative BRAKING, not Breaking.......altho both can happen.

Also a former BattleBot builder..WreckTangle (superheavyweight) Titanium skin, twin 1.5hp 24volt motors(regen braking), 4wheel drive, differential steering, CO2 powered hammer spike.

MikeVDS · Post by **MikeVDS** » Tue Feb 06, 2007 4:08 pm

Which years did you compete? We were 99, 2000 we died before we got to the fight, and then 2001.

My favorite was Executioner in 99.

If you want to check out the regenerative stopping, you want to look for regenerative BRAKING, not Breaking

Good point, I never put much thought into that word, but brakes -> braking makes sense.

spectabillis · Post by **spectabillis** » Tue Feb 06, 2007 4:19 pm

EspressoDude wrote:Pneumatic systems are not very efficient. If you have used an air compressor and air powered motorized tools, you will be familiar with the heat generated at the compressor head, and the cold and often ice formed on pneumatic tools. This is wasted energy.

waste is fine by me, i will let the bike builders go green. didnt have much heat buildup with a compressor and never any ice. guess i didnt use it enough to get to that point but i agree the overall efficiancy sucks, why i go all electric now.

Also a former BattleBot builder..

there's a few botbuilders who poke around on this board but its sporadic mentions in posts. i like the engr and whats done with it and enjoyed seemen and srl when they took it to a massive scale. more show than competing, until someome does it with art cars.

thats considered performance art right? randomly crushing peoples art cars? maybe if someone dpw goes madmax in one of their loaders...

gyre · Post by **gyre** » Tue Feb 06, 2007 4:27 pm

I think regenerative braking in electric is inefficient on level ground.
I wouldn't bother unless you have hills like sf.

EspressoDude · Post by **EspressoDude** » Tue Feb 06, 2007 5:01 pm

Battlebots:

2001 with Parasitic @ Treasure Island, WreckTangle not done yet, then BBots all died

Spend about an hour with a pneumatic die grinder and u will end up with about 1/4" ice all over it (gloves needed)

Regen braking comes automatically with Vantec Controllers (dc motor)

ART CAR DESTRUCTION DERBY? WaHoo!!!! talk about major moop

MikeVDS · Post by **MikeVDS** » Tue Feb 06, 2007 5:09 pm

I think regenerative braking in electric is inefficient on level ground.

The energy efficiency isn't really changed, but it's not considered worthwhile unless you're collecting energy from down a hill etc. On flat ground you're not adding any potential energy into the system once you're up to speed, and then all of the energy consumption is from friction and wind resistance. When climbing a slope you're putting energy into climbing a hill that you can collect when going back down. Currently we burn that up with our brakes, making heat.

Current systems aren't up to par but the idea shouldn't be easily dismissed. A low friction, low wind resistance vehicle using a high efficiency regenerative braking system would need very little fueling. Even though you're not collecting energy from going down hills, you're not putting the energy into going up them in the first place. If your losses are small then you collect large amounts of the energy you spent to get up to speed.

But no one wants to ride around in a car that looks like a long dildo. If they did we could use the light vehicles that already get 1000 miles to the gallon. Not to mention that they would not mix well with current vehicles. A regenerative braking system in one of these vehicles could keep a fairly high MPG rating even when needing to stop and go, as we'd expect in normal traffic.

gyre · Post by **gyre** » Tue Feb 06, 2007 5:23 pm

There are other problems with adding braking recovery.

I have proposed a light highway system that would separate ultralight vehicles from traffic over 2000 pounds.
If anyone is interested, email me.
The response from highway departments has been quite positive.
You could expect 75-100 mpg from a safe two passenger car.
That's with good aerodynamics and a standard modern gas engine.
Electric motors and regen braking is quite unneeded to reach this level.
At 60 mph, air conditioning would use more power than the propulsion.
It is my belief that the real gains are in highway use rather than city driving.

MikeVDS · Post by **MikeVDS** » Tue Feb 06, 2007 5:31 pm

Sounds like a great proposal. I bet in certain areas of the country a market for these vehicles could get a good start and grip in our culture if they had some infrastructure.

gyre · Post by **gyre** » Tue Feb 06, 2007 5:47 pm

There are actually no technical barriers.
The savings in roadbuilding outside of cities is enormous.

All I have to do is get everyone to agree.
How hard could that be?

MikeVDS · Post by **MikeVDS** » Tue Feb 06, 2007 6:10 pm

That's the easy part. Pshh.

That's why I'm thinking getting people to own these vehicles might be easier in some areas until it catches on. It's a rough sell. We've had mass manufactured vehicles claim to get 80mpg and a friend who reported getting 60MPG, but people unfortunately don't (didn't?) want those.

Post by **mdmf007** » Tue Feb 06, 2007 6:14 pm

I wrote a paper at univeristy about the advantages of using a rail and hib system where cars and tractor trailers could get on a train like a ferry and hiop a ride to the next hub, or thfough.

i.e
A tractor trailer going to Miami from Seattle could take a Ferry(train) from seattle to Boise, Boise to KC, KC to Tallahassee, Tallahassee to Miami, or drive any portion thereof.

Trains can move a ton of freight up to 990 ton miles per gallon of diesel.
compared to an average of 119 ton miles per gallon for a tractor trailer.

Looking atthe math it is 8 times as eficient to move freight via rail.

My models indicated a potential savings of almost 50% of the road diesel burned in the US. That is a lot of diesel - that only included 3o hubs at the busiest shipping centers.

Would not require any new rail other than sidings for each hub station.
(cars would be welcome too)

later all.

MikeVDS · Post by **MikeVDS** » Tue Feb 06, 2007 6:31 pm

That's a great idea that I've never heard proposed before.

gyre · Post by **gyre** » Tue Feb 06, 2007 6:43 pm

The rail idea makes sense.
It is available to some extent, but not enough.

Do you have a copy of that paper?

Post by **mdmf007** » Tue Feb 06, 2007 6:54 pm

Mike -
Ill have melissa dig it out of the computer and drop it somewhere for you guys. I am sure it has been thought of before and tried to find a source so as not to plagarize them (I wrote it in the pre Internet days) couldnt find one, so i grabbed charts from USDOT, States and compiled it all into a readable format.

later all