Flash Point Calculations

The flash point is a test designed to determine the temperature at which the vapor above an oil will momentarily "flash" or explode. There are three common tests: the open cup (D92), the Pensky-Martens (D93) and the Tag (D56) closed tester for light oils. The oil is heated at a constant rate and a test flame is periodically introduced into the vapor. The flash point is the temperature at which the oil vapors "flash". Results vary somewhat, depending on the test method.

The following methods are available for calculation of the flash point in PRO/II:

Nelson

This method was devised by W. L. Nelson and computes the flash point with this equation:

Flash Point, Deg F = 0.64*T - 100

where:

T = Average ASTM temperature of 0 to 10 percent distilled material, deg F

This method is not accurate enough to distinguish between the various laboratory tests.

Flash Point Calculation using API2007 method

The following equations are used to estimate the flash point of petroleum fractions:

For a closed cup flash point:

FP = 0.3577 (TIBP + T5%) - 119.1

where:

FP = flash point, F

TIBP= ASTM D86 initial boiling point temperature, F

T5%= ASTM D86 5% temperature, F

Flash Point Calculation using API1987 method

The following equation is used to estimate the flash point of petroleum fractions:

1/TFP  = -0.014568 + 2.84947/T1 + 1.903 * 10-3 ln T1

where:

TFP  = flash point (Penske-Martens Closed Cup, ASTM D93) of petroleum fraction, in degrees Rankine

T1 = ASTM 10% temperature for petroleum fractions or normal boiling point for pure compounds, in degrees Rankine