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I think I found my own answer, Bob

Flash point is the lowest temperature at which a liquid can form an ignitable mixture in air near the surface of the liquid. The lower the flash point, the easier it is to ignite the material.

For example, gasoline has a flash point of -40 degrees C (-40 F) and is more flammable than ethylene glycol (antifreeze) which has a flash point of 111 degrees C (232 F).

A closely related and less common term is fire point, the temperature at which the flame becomes self-sustained so as to continue burning the liquid (at the flash point, the flame does not need to be sustained). The fire point is usually a few degrees above the flash point.

It appears that the fire point is more of what is of interest - so that being a few degrees above the flash point makes it even a bit better.

----- Original Message -----

From: Bob Darrah

To: Rotary motors in aircraft

Sent: Thursday, December 01, 2005 10:46 PM

Subject: [FlyRotary] Brake fluid flash point

Ed,

Me thinks that maybe you have a misunderstanding of the term "flash point". It is not what most people assume it is. I say this because the flash point of the gas in your tank is something like 60 degrees BELOW 0. That means that on a hot day, the temperature could exceed the flash point by 160 degrees and you don't see too many people concerned about that.

Bob Darrah

----- Original Message -----

From: Ed Anderson

To: Rotary motors in aircraft

Sent: Thursday, December 01, 2005 7:43 PM

Subject: [FlyRotary] Re: fuel/brake lines

Rusty,

I went with the new high flash point aircraft brake fluid (MIL-H-83282)- flash point is 450F vs 240F for the old stuff. I had to get a gallon of the stuff (enough to probably last me for years and years and years), but after the fire, I feel a bit more comfortable that it won't go up with the temp a little over the boiling point of water. I considered some of the auto brake fluids - but have heard some horror stories about incompatibility with aircraft seals - I know there is some DOT formulas that supposedly are compatible - but did not feel like experimenting {:>)

Ed