Technical - Flash point ASTM D 3278

This video briefly explains about the flash point of the liquid and how it has to be measured as per ASTM D 3278.

The FLASH POINT of a volatile material is the lowest temperature at which vapours of the material will ignite, when given an ignition source. Means, the temperature at which liquid or solid change to gasious state.

The FIRE POINT (the lowest temperature at which vapours of the material will keep burning form min 5 Sec,  after being ignited and the ignition source removed) is higher than the flash point.

Neither flash point nor fire point depends directly on the ignition source temperature, but it may be understood that AUTOIGNITION TEMPERATURE (or KINDLING POINT of a substance is the lowest temperature at which it spontaneously ignites in normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion) will be considerably higher than either the flash or fire point.

The flash point is a characteristic that is used to distinguish between flammability and combustibility. Ex Petrol is flammable and Diesel is combustible.

It is also used to differentiate the fire hazards of materials.  

Ex…
• Liquids which have a flash point less than 37.8 °C (100.0 °F) are called flammable

• Liquids having a flash point above that temperature are called combustible.

Watch video for more details:

These test methods cover procedures for determining whether a material does or does not flash at a specified temperature or for determining the lowest finite temperature at which a material does flash when using a small scale closed-cup apparatus. The test methods are applicable to paints, enamels, lacquers, varnishes, and related products having a flash point between 0 and 110°C (32 and 230°F) and viscosity lower than 150 St at 25°C (77°F).
Note 1—Tests at higher or lower temperatures are possible.
Note 2—More viscous materials may be tested in accordance with Annex A4.
Note 3—Organic peroxides may be tested in accordance with Annex A5, which describes the applicable safety precautions.
Note 4—The U.S. Department of Labor (OSHA, Hazard Communications), the U.S. Department of Transportation (RSPA), and the U.S. Environmental Protection Agency (EPA) have specified Test Methods D3278 as one of several acceptable methods for the determination of flash point of liquids in their regulations.
Note 5—These test methods are similar to International Standards ISO 3679 and ISO 3680.
The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
This standard should be used to measure and describe the response of materials, products, or assemblies to heat and flame under controlled conditions and should not be used to describe or appraise the fire-hazard or fire-risk of materials, products, or assemblies under actual fire conditions. However, results of the test may be used as elements of a fire-hazard or a fire-risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard or fire risk of a particular end use.

Let see the lab testing method:

How to test the Flash point and the fire point at site levels:

Do not conduct this at home or along with children or without PPH tools.

Flammable vs Combustible? Flammable vs Inflammable?
The words “flammable liquid” and “combustible liquid” have very specific meanings in the context of fire prevention and suppression, as defined by the Code of the National Fire Protection Association, Washington D.C. A flammable liquid has a flash point of 100oF or less; if the flashpoint is above 100oF it is a combustible liquid.

This definition is different from ordinary common speech. In ordinary speech, the words “combustible” and “inflammable” are used to mean a material that can burn or support combustion. Some people are thrown off by the prefix “in” (“inflammable”) and think that “inflammable” means “not flammable” which is incorrect.

Obviously, solids and gases can also burn. The material does not have to be a liquid. Sometimes the designation “flammable gas” is used for a chemical which is stored as a gas and has a flash point less than 100oF.

National Fire Protection Association Classifications for Flammable and Combustible Liquids.

The NFPA divides flammable and combustible liquids into classes based on flash point and boiling point, as shown in table 1

Table 1: NFPA Classifications

Class	Flashpoint and Boiling Point
I A Flammable Liquid	Flashpoint 73oF or less and boiling point 100oF or less
I B Flammable Liquid	Flashpoint 73oF or less and boiling point over 100oF
I C Flammable Liquid	Flashpoint over 73oF but 100oF or less
II Combustible Liquid	Flashpoint between 100oF and 140oF
III A Combustible Liquid	Flashpoint between 140oF and 200oF
III B Combustible Liquid	Flashpoint above 200oF

Note that the boiling point is specified only in the I A and I B classifications.
The I A Flammable Liquid is the most dangerous of all flammable and combustible liquids.

Let see some label example:

For more details: http://niohenvis.nic.in/statistics_page/nfparating.html

Many thanks to google.com and doc88.com from where the details have been collected.