silicon anti-foaming agent (Full Version)

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geofferama -> silicon anti-foaming agent (9/12/2004 9:02:01 AM)

I know everyone uses Armor All, but if its the silicone that's keeping the foam away, wouldn't any of the 'pure' silicone lubricant sprays accomplish the exact same task?

just curiosity, but i'd rather not kill my motor finding out



downunder -> RE: silicon anti-foaming agent (9/13/2004 3:00:31 AM)

Chances are it would work very well. Armor All certainly does the trick but the latest batch apparently doesn't have silicon anymore so an alternative would be nice to know about.



geofferama -> RE: silicon anti-foaming agent (9/13/2004 5:46:55 PM)

Well, i have this can of Kellog's Pure Silicone "Not Just Another Silicone Spray" that i keep eyeballing everytime i think about my nitro fuel. Ingredients (listed by CAS #) are propane, 2-Methylpropane, heptane and (not listed by CAS#) polydimethylsiloxane. PDMS is the same thing in Armor All and i picked this spray up at my local hardware store.

[image]http://ts.smoothcorp.com/cornerhardware/138185.205x599.jpeg[/image]
Its not the exact can, but close enough. The 4oz spray can is 110B



downunder -> RE: silicon anti-foaming agent (9/13/2004 11:05:53 PM)

I'd say it's definitely worth a try and if it's like Armor All then you only need the tiniest amount in a gallon of fuel. Shake the drum until it's foaming like crazy then give a very quick spray over the opening and see if the foam instantly disappears.



Fuelman -> RE: silicon anti-foaming agent (9/14/2004 12:36:09 PM)

Carefull !
Too much silicone anything in the fuel will cause deposits on the glowplug with a possible degrading of plug life or performance or reliability.
A drop or two is the maximum amount I would recommend.



geofferama -> RE: silicon anti-foaming agent (9/14/2004 3:55:07 PM)

I'll give it a try on some fuel in my fuel bottle. I'm using O'Donnell 20% (which I've noticed doesn't have its oil content listed, but I've read as being 16%) and I really should switch to something with a higher oil content. I ran some Monster Brew that a friend had and at the same settings the engine was running much much richer.


I gave the Ke's a very short spritz. 290cc's of fuel in my 500cc fuel bottle and even with vigorous shaking, the foam only rises up to the 300cc mark. I never tried Armor All before so is this Normal/Bad/God Help Me?



rslstft -> RE: silicon anti-foaming agent (9/30/2004 4:14:48 AM)

I've been mixing my own fuels (mostly 15% and 30% nitro with 18-20% oil) for a little over 3 years now and quit using any "anti-foaming" additive about a year and half ago and never noticed any difference in engine response and didn't change any of the needle settings at all. I have 7 four strokes and 4 two strokes and they all run the same without the Armor All (which I used to use) added. So, I guess I'm not even sure anything is need to prevent foaming. Next time you mix some fuel, before you add the anti-foamer, shake the bottle and watch how much it foams - not much if at all! Maybe it has something to do with the brand of oil used?? I have always used Klotz oil and some of my engines have more that 10 gallons through them.

Russ



XJet -> RE: silicon anti-foaming agent (10/4/2004 11:23:19 PM)

Yes, the brand/type of oil can have a huge effect on foaming.

Just last week I was helping another flier set up a new 40-sized trainer with a TT46 in it.

We decided to run the engine in by putting a couple of tanks of fuel through it on the ground so we used some of the break-in fuel I made up for my own engines. This fuel has a fair bit of castor oil in it and a little Coolpower blue.

After about a minute's running there were quite a few very fine bubbles streaming up the fuel line into the fuel-filter. They were collecting there so that if you throttled back and then opened up again, the engine would quite because it would suck the big reservoir of air that had collected in the filter body.

Obviously this was no good for flying so we replaced the clunk line and all the external lines -- but that didn't change anything.

We messed around checking that the tank was isolated from vibration as much as possible -- but that didn't help either.

Finally (on a hunch and after about 15 minute's running-in) we switched to straight CoolPower blue and the problem went away.

Obviously the castor content of the fuel used for running in was contributing significantly to the foaming problem.



Woody 51 -> RE: silicon anti-foaming agent (10/4/2004 11:30:01 PM)

But what causes the foaming?
I have been thought this excercise before with novices and usually find that an out of balance prop is one of the most common root causes.
Another is having a tank that is not properly insulated from the model with foam rubber etc.
Adding silicone covers the symptoms, but does not solve the problem.



Fuelman -> RE: silicon anti-foaming agent (10/5/2004 12:38:39 PM)

Oil does make a difference. Castor oil will tend to foam easier and the bubbles last longer than any synthetic oils I know of. Some companies that sell oils suitable for making fuel with have a anti-foam agert blended in.
Ballanced props, padded tanks, good lines all contribute to minimizing foaming or air in the line issues



Justrace -> RE: silicon anti-foaming agent (10/29/2004 9:41:40 PM)

The synthetic oil from Morgan has antifoam properties. That's the green color oil.

http://www.morganfuel.com/homebrew.htm



geofferama -> RE: silicon anti-foaming agent (10/30/2004 9:12:32 AM)

quote:

ORIGINAL: Woody 51

But what causes the foaming?
I have been thought this excercise before with novices and usually find that an out of balance prop is one of the most common root causes.
Another is having a tank that is not properly insulated from the model with foam rubber etc.
Adding silicone covers the symptoms, but does not solve the problem.


I'm actually kindof surprised to see this thread went for so long even w/out some newbie resurrecting it. I was asking about silicon additives b/c I've got a nitro truck and they tend to bounce around. That doesn't even account for the non-existant vibration insulation. But as far as planes and heli's go you're mostly right, but that doesn't mean you should cross it off your trouble-shooting checklist.



downunder -> RE: silicon anti-foaming agent (10/30/2004 5:17:27 PM)

What the silicon does is reduce the surface tension of the fuel so large bubbles (foam) can't form from vibration. You can't entirely eliminate bubbles because you can't eliminate surface tension.



PhilNZ -> RE: silicon anti-foaming agent (11/28/2004 7:30:16 AM)

Hi,
Ok I have just given my Fuel a damn good shaking and the amount of bubbles / foam was so small it and it settled within a few seconds. I am sure that I gave it 3 to 4 times more shaking that it would get in the air even doing full on rolls and loops..

Container used was a 2 litre with 500 mls of New fuel, bubble rise / foam was about 1 to 2 mils
and settled by the time i went to measure the rise ..

Is it advisable to add silicon to methanol ?

This mix is as follows

17 % Pressed castor oil
3 % Acetone
10 % Nitro
70% Methanol

Phil



XJet -> RE: silicon anti-foaming agent (11/28/2004 7:47:17 AM)

quote:

ORIGINAL: PhilNZ
This mix is as follows

17 % Pressed castor oil
3 % Acetone
10 % Nitro
70% Methanol


What's the acetone for?

The only time I ever used acetone was when I was trying to get some Castrol R to dissolve in methanol -- and it wasn't partcularly successful.

I have never used it since and everything seems to work sweet with pure castor, or Klotz or Coolpower.



PhilNZ -> RE: silicon anti-foaming agent (11/28/2004 8:00:43 AM)

Hi XJet,
Ok the acetone does 5 things in a 2 stroke
and 6 things in a 4 stroke.

1/ Its helps stop the methanol absorbing moisture

2/ Helps burn some of the Oil

3/ Helps in the mixing of the oil into the methanol.

4/ Will increase the power slightly

5/ Helps keep the varnish out of engines also

6/ Stops kick back in a 4 stroke ( I can't confirm this but others have )

Also Castrol R and R2 should not be used in RC engines as it is not designed to mix with methanol.

Phillip



XJet -> RE: silicon anti-foaming agent (11/29/2004 8:00:58 AM)

quote:

ORIGINAL: PhilNZ
1/ Its helps stop the methanol absorbing moisture

Never had a problem with moisture with my fuel -- and I've got a 20lt metal can of methanol I'm still using from about 5 years ago without any ill effects.

quote:

2/ Helps burn some of the Oil

Is this a *good* thing? I always thought that when oil passed through the engine without burning it added valuable extra cooling and that "burnt" oil provided no lubrication.

quote:

3/ Helps in the mixing of the oil into the methanol.

Again, I've never had any problem with pure castor or any of the synthetics (blended or otherwise)

quote:

4/ Will increase the power slightly

*very* slightly. The calorific value of acetone is just 28% higher than methanol so at a percentage of (say) 5%, the total additional energy available is just 1.4%.

quote:

5/ Helps keep the varnish out of engines also

How does it do this if it promotes burning of the oil? Degummed castor that passes through an engine produces no varnish but if it's burnt it sure does.

quote:

Also Castrol R and R2 should not be used in RC engines as it is not designed to mix with methanol.

You're right -- but Castrol state that Castrol R *is* suitable for use with methanol -- albeit I think the problem is the fact hat model engines require higher percentages than can be held in solution with methanol.



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