"Shortwave Sportfishing" wrote in message
...
On 1 Jul 2005 08:48:37 -0700, wrote:



K. Smith wrote:
zee-qi wrote:
hi people.
i would ask you something.Who can explain me how does work diesel
engine.?and what kind of system it need to work normally.
..thx for your ansver...


They use diesel fuel which has a very low auto ignition temp (about
200-210C) so if a "vapour" of diesel sees 200C it auto ignites without a
spark.

Petrol gasolene has a higher auto ignition temp (250-280C) so it needs
an electric spark to ignite it.


Are you sure you're explaining that correctly?

I wondered the same thing - I just read what Karen wrote.

It's my understanding that the auto-ignition point isn't relevant with
gas engines because it doesn't rely on compression for ignition - it
relies on a spark. Which, at least to my mind, would indicate gas
would have a low flashpoint and a high auto ignition temperature.
Conversely, a diesel has a high flash point and a low auto ignition
temperature which is why the compression is high.

Also, it's my understanding that the reason some gas engines have high
compression ratios is more for power production.

Or am I wrong?

------------------------------------------------------
Gasoline:
Flash Point: -40 degrees (Estimated)
Autoignition Temperatu 480 degrees F
Flammable Limits In Air: UEL: 7.1% - LEL: 1.3%

http://www.brownoil.com/msdsgasoline.htm
--------------------------------------------------------

Diesel Fuel:
Flash Point: 100 degrees F PM (minimum)
Autoignition Temperatu 494 degrees F
Flammable Limits In Air: UEL: 5% - LEL: 0.7%

http://www.brownoil.com/msdsdiesel.htm

--------------------------------------------------------------------------------------

Gasoline is by far more volitile, especially when looking at the flash
point.