6 replies to this topic

[stu]

Dear Sir,
Will you please clear me the doubt, is there any relationship between Flash point, Fire Point, Boiling point & Auto ignition point .Is the temperature increases respectively as sequence mentioned above for any liquid( may be Hydrocarbon liquids).
Thanks in advance
Stu

[resmihadi]

dear jatin and stu

for boiling point
it should be temperatur at which vapour pressure = system pressure
if the system pressure higher or lower than atmosphere so the boiling point is
just follow thermodynamic law

resmi

[gvdlans]

There is an equation for estimating flash point based on boiling point for pure organic compounds in the following book:
Daniel A. Crowl and Joseph F. Louvar, Chemical Process Safety, 2nd edition.

The equation is eq. 6-1 in this book and was based on following article:

K. Satyanarayana and P.G. Rao, "Improved Equation to Estimate Flash Points of Organic Compounds," Journal of Hazardous Materials (1992), 32:81-85

The equation is a bit too complex to put in this forum.

I don't think there is a relation between autoignition temperature (AIT) and boiling temperature. I have seen a graph by Zabetakis of AIT vs average Carbon chain length for alkanes. It is figure 4-1 in the following: http://www.epriweb.c...00001005035.pdf

[Zauberberg]

What is fire point?

Autoignition temperature is extremely dependent on fluid composition and physical properties, and it is usually related to plant operations where you can expect sudden fluid spillage from the field equipment at process conditions. Depending on fluid properites and composition (and process conditions), you may expect that - in the case when fluid reaches the atmosphere at process conditions - it undergoes autoignition. For example, autognition temperature of heavy distillates is lower than gasoline (naphtha) autoignition temperature.

Flash point is lower than the corresponding boiling point (or IBP - initial boiling point for hydrocarbon mixtures). Usually, the order of sequence is: Flash point < IBP < Autoignition temperature, but we don't know what is the fluid in question here.

Regards,

[lacertian]

Fire point is the temperature at which a fuel can be ignited and at which it will continue to burn. Wikipedia suggests the burn only need to last for 5 seconds, but to me this sounds like a criterion taken from a specific test.

I would be wary of correlations taken from the literature for estimating these various criteria. They can provide useful estimates, but the temptation is to use them as a substitute for properly determined experimental values.
The exact composition of the fluid will affect the final value and if dealing with complex mixtures of hydrocarbons there could be some significant variation from calculated values. There could even be some variation between different samples.

It would be interesting to hear the original poster's intention. Was this a general query or is there a specific end in mind? I agree that it would be interesting to know what the fluid in question is. It may be worth considering a few laboratory tests.

[gvdlans]

A term closely related to flash point 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. See http://www.ilpi.com/...flashpoint.html