quick noobie question...

driveit · Post by **driveit** » Thu Feb 15, 2007 8:48 pm

can i run a jam-jar pulse jet on rubbing alcohol? just wondering........

larry cottrill · Post by **larry cottrill** » Fri Feb 16, 2007 1:49 am

driveit wrote:can i run a jam-jar pulse jet on rubbing alcohol? just wondering........

I've done it with small jam jars, but this was under "ideal" conditions - indoors in an air-conditioned space, low humidity, etc. There is a "better than average" rubbing alcohol available at Wal-Mart: 91 percent Isopropyl alcohol (as opposed to the usual 70 or 75 percent) and this is definitely better to use. You could probably find this concentration at a pharmacy (chemist's shop, drug store, etc.).

L Cottrill

Mark · Post by **Mark** » Fri Feb 16, 2007 2:01 am

I just tried some 91% isopropyl that I had under my sink in several of my jars and several sized holes on the same jar. I wasn't able to get any to sustain, just the typical rev and die. Perhaps 99% would be better.
Remember methanol is the simplest alcohol, then ethanol, and then isopropyl. As you go up the ladder, the fuel/air ratio becomes more critical, the flammability range more fragile.
I also went outside to see if that would help. It didn't. It's going to get down to 27 F tonight.
I have some Everclear 190 proof that works pretty good, it's ethanol that you can drink, but costs an arm and a leg. It likes a slightly larger holed lid than methanol.
Mark
http://www.drinksmixer.com/desc494.html

driveit · Post by **driveit** » Fri Feb 16, 2007 3:51 am

i actually saw 99% rubbing alcohol at wal-mart today, but forgot to pick it up, duh (lol). ill buy it next time im workin.

metiz · Post by **metiz** » Fri Feb 16, 2007 8:19 am

I usually run them on this stuff http://upload.wikimedia.org/wikipedia/c ... lasche.jpg
cheap and works just fine with me

Mark · Post by **Mark** » Fri Feb 16, 2007 2:20 pm

Now that I think/focus on this subject, I have in the past tried isopropyl alcohol and remember that I wasn't too enamored with it. When it did start to run in my jars it often flamed-out on me out of the blue, it was just more fussy. And I recall having a hard time of it when I tried to run my Dynajet with it, priming it and trying my best. I could only get weak pops and woofs out the tailpipe. And it's not like methanol where on some of my pulsejets I can do an instant bang start from a "cold" engine, by which I mean room temperature, zero to sixty in one second, like a gunshot the jet is up and running. You can find iso HEET right next to the "metho" HEET at Walmart, it is perhaps as "dry" as you can get. Look for the red bottle.
Perhaps I will try isopropyl one more time with some jam jars, but I have a feeling I won't like the results. I'm sure you could run a pulsejet or even a jam jar if you fiddled with it long enough, it's just going to be like my funny dachshund depending on how you look at it. You might say he's stubborn, or you might say he is independent. But he will taunt you and gaze at you until you start to understand that what he wants is oftentimes stronger than what you want. He will wait you out, but I really love him.
Mark
http://www.goldeagle.com/heet/products.htm
http://www.engineeringtoolbox.com/explo ... d_423.html

Mark · Post by **Mark** » Fri Feb 16, 2007 2:44 pm

But this is not the whole story. If you look at the chart I posted previously, you will see ether, (diethyl ether), has an even greater range of flammability than methanol. But you can forget about using it like methanol in a jam jar. The fuel/air ratio will go balistic and it becomes way too rich to even get the flame to travel down the hole into the jar most times. I even tried diluting it with methanol and it really mucks things up even in small amounts if you are jam jarring.
Another good example is acetone, again the flame is reluctant to even go into the jar. And if you look at it's flammability range it is almost identical to isopropyl which has at least run for me but flames out suddenly for no apparent reason. I also tried carbon disulfide, look at the range and recall that the temperature of steam will ignite it! Now you might think it would be a peppy fuel too, but it is not. I think I have tried/bought most every common flammable liquid.
Mark
http://www.engineeringtoolbox.com/explo ... d_423.html

Mark · Post by **Mark** » Fri Feb 16, 2007 3:07 pm

"There are also systems with negative deviations that have vapor pressures that are lower than expected. Such a deviation is evidence for stronger intermolecular attraction between the constituents of the mixture than exists in the pure components. Thus, the molecules are "held in" the liquid more strongly when a second molecule is present."

http://en.wikipedia.org/wiki/Vapor_pressure
http://en.wikipedia.org/wiki/Boiling_point

driveit · Post by **driveit** » Fri Feb 16, 2007 4:38 pm

nvm this post. i was going to ask of a pic but i got one.....

Mark · Post by **Mark** » Fri Feb 16, 2007 5:50 pm

Maybe some denatured alcohol would be another avenue.
Mark
http://www.sunnysidecorp.com/shellac.htm

driveit · Post by **driveit** » Fri Feb 16, 2007 8:37 pm

would you say denatured alcohol is as good as methanol? any other products, like HEET, that you would recomend???

Thanks,

Driveit

Mark · Post by **Mark** » Fri Feb 16, 2007 10:57 pm

I would conclude methanol is the king for jam jar running. Ethanol is almost as good from what I have found, although I can tell it isn't better than methanol and isopropyl sucks even if pure. I just did several more tests with pure isopropyl and have been traumatized after all sized jars and hole sizes I have have failed. The initial whoosh is always much weaker than with methanol too, the flame speed lags.
Mark

Mark · Post by **Mark** » Fri Feb 16, 2007 11:23 pm

http://mywebpages.comcast.net/photonsto ... Guide.html

evildrome · Post by **evildrome** » Sat Feb 17, 2007 12:44 am

Hi Mark,

I bought a European version of that stove (very swish looking all aluminium job) just out of curiosity to see how it worked. In the one I had at least, its not pulsatory. It consisted of an open ended can with burner holes at the top and a double wall that runs down into the cup. The fuel (ethanol) is drawn up into the wall space by capillary action and is then vapourised by transmitted heat from the can walls. The fuel vapour escapes at a small pressure and ignites very well. I was able to boil a pint of water with it much faster than I expected.

Cheers,

Wilson.

Mark · Post by **Mark** » Sat Feb 17, 2007 12:50 am

I knew it didn't pulsate, I just wanted to point out how isopropyl alcohol is prone to making soot. You wouldn't think alcohol would do that.
Mark

"but does not burn efficiently in alcohol stoves" I wonder if that applies to jam jars too???

"Try to avoid using Isopropanol. This is the main ingredient in Red Heet and in rubbing alcohol. Most rubbing alcohol comes in at only 70% Isopropyl alcohol (30% water) and will not burn in a stove. You will need at least 91% pure rubbing alcohol to burn at all in your stove. Isopropanol actually has a higher heat content than either methanol or ethanol (approx 14,000 BTUs/lb) but does not burn efficiently in alcohol stoves. If you do use it be prepared for a flickering yellow flame (an indicator of incomplete combustion) and serious amounts of soot on and sometimes in your pot. Yech."

http://www.epinions.com/content_3914899588

www.pulse-jets.com