Flash and fire point

Flash point is the temperature to which a combustible liquid must be heated to give off sufficient vapours to fonn momentarily a flammable mixture with air when a small flame (of standard dimensions) is brought near the surface of the liquid under 

It is therefore the minimum temperature at which, provided other conditions are satisfied, only a momentary flash is produced. The flash immediately disapjtears for want of more vapours, i.e., the temperature is not high enough for the vapours to be formed at sufficiently high rate. 

At a si ightly higher temperature, the heat from the flash becomes sufficient to evaporate more liquid and maintain combustion. This minimum temperature (usually 5 to dCTC higher than Flash Point) at which an oil gives off sufficient vapour which when ignited continues to bum for at least 5 seconds is know it as FIRE POINT of the oil. 

A fire may develop if a set of the following three conditions (known as FIRE TRIANGLE) is simultaneously satisfied  

Flammable liquids are volatile and speed of evaporation (Evaporation Rate) increases appreciably when the liquid is heated. The vapours being heavier than air, go on accumulating at the lowest level, such as pits under the tanks, where their concentration reaches within the explosive range and explode and burn in the presence of an ignition source. This can be prevented by mechanical ventilation of any pits at the bottom of oil tanks—this increases the rate of diffusion of vapours and the explosive range is not approached. 

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Smoke, Flash, and Fire Points. These thermal properties may be determined under standard test conditions (57). The smoke poiat is defined as the temperature at which smoke begias to evolve continuously from the sample. Flash poiat is the temperature at which a flash is observed whea a test flame is appHed. The fire poiat is defiaed as the temperature at which the fire coatiaues to bum. These values are profouadly affected by minor coastitueats ia the oil, such as fatty acids, moao- and diglycerides, and residual solvents. These factors are of commercial importance where fats or oils are used at high temperatures such as ia lubricants or edible frying fats. 

Methods of test for petroleum and its products. Determination of open, flash and fire point. Pensky-Martens method. 

A. FLASH AND FIRE POINTS BY CLEVELAND OPEN CUP METHOD (COC). The Cleveland Open Cup Apparatus is described as Method 4294 (Sept 1965) of Federal Test Method Standard No 141a... 

The results of this program are contained in reference (10) Table II presents a comparison of the selected physicochemical properties of Sulphlex-233 and an AC-20 grade asphalt cement used in the FHWA study. The table indicates that their properties are generally quite different, particularly the specific gravity, penetration, viscosities, and flash and fire points. However, from a practical standpoint, as the materials are used in the field, these differences are not highly significant. 

Flash and Fire Points, ° C. Cleveland open cup (ASTM D 92-46) if not otherwise designated. Closed cup (ASTM D 56-36) will be designated as such. 

Cleveland Open Cup (COC). An apparatus used for testing flash and fire points of flammable liquids... 

Ikeda, H. 2004. Safety design of PUREX liquids system - The flash and fire points. J. Nucl. Sci. Technol. 41(4) 534-536. 

Cleveland Open Cup apparatus used to determine the flash and fire point of all. 

When a fat or oil is heated, thermal instability may cause decomposition, and depending on the temperature reached, subsequent combustion of volatile gaseous decomposition products (Mehlenbacher, 1960). The thermal stability of fats and oils is thus essentially a chemical characteristic. However, stability is characterized by measuring certain critical temperatures, the smoke, flash and fire points, at which certain heat-induced changes become apparent. It is appropriate, therefore, to include here methods for measuring these critical points. 

Measurement of smoke, flash and fire points is carried out subjectively by observing the surface of an oil sample while the sample is being heated. (The critical temperatures are higher than the upper limit of the melting point range of a fat.) The smoke point is the temperature at which the sample begins to give off a continuous stream of bluish smoke, observable... 

Standard methods for the determination of the critical temperatures are published by the AOCS (AOCS Official Methods Cc 9a 48 (smoke, flash and fire points by an open cup method), and Cc 9b-55 and Cc 9c 95 (flash point by open cup methods), Firestone, 1998) and by the British Standards Institution (BS 684 Section 1.8 1976 (smoke point), BSI, 1976b and BS 684-1.17 1998/ISO 15267 1998 (flashpoint by a closed cup method), BSI, 1998b). 

Smoke, Flash, and Fire Point—Cleveland Open Cup Method (Cc 9a-48) determines the temperatures at which fats and oils smoke, flash, or burn. Smoke point determinations sometimes are used to follow degradation of frying oils with use. 

Other physical properties such as the smoke, flash, and fire points of oils and fats are measures of their thermal stability when heated. The smoke point is important for the oils and fats used for deep-frying. The flash point and fire points are a measure of residual solvent in crude and refined oils and are also a safety requirement. 

Smoke, flash and fire points Oxidative state °C... 

Figure 1. Relationship between free fatty acid content and smoke, flash, and fire points of cottonseed and peanut oils.----------, Refined cottonseed oii --------, peanut oil.

Flash and Fire Point. Flash point is the temperature at which the volatile products are evolved at such a rate that they are capable of being ignited but not supporting combustion. At the fire point, the accumulated breakdown products are capable of supporting a flame on their own. A crude cottonseed oil with a fatty acid content of 1.8% was found to have a flash point of 560°F or 293.3°C. Solvent-extracted oils can have a low flash point because of a solvent residue. A flash point analysis would identify this crude oil deficiency to prevent an accidental fire or explosion in an atmosphere that was not explosion proof. Crude vegetable oil shipments received with a flash point below 250°F are rejectable by most trading rules. Figure 1 shows the relationship between free fatty acid content, smoke, flash, and fire points of processed cottonseed and peanut oils. 

The smoke, flash, and fire points of soybean oil have been determined by the Cleveland Cup method and show considerable variation. Dickhart (117) reported a smoke point of 138°C while Detwiler and Markley (76) reported 241-250°C. 

Flash and fire points are two very important physical properties, which are of interest from the standpoint of safety and ignition characteristics. The flash point is the temperature at which the vapor above an oil will momentarily flash when in the presence of a flame, while the fire point is the temperature at which the vapors are vaporized quickly enough to have a sustained flame. The flash point is determined by using an open cup and Pensky-Martens closed tester for heavy oils and a tag closed tester for light oils. The vapor pressure-temperature relationship can be written as... 

The most important property for a high-temperature HTF is its thermal stability at exceptionally high temperatures. These HTFs are normally used above their flash and fire points in closed and airtight systems. In many applications, an inert gas such as nitrogen is utilized in the head space of the holding/ expansion tank. 

The fire point is the temperature to which the product must be heated under the prescribed test conditions to cause the vapor-air mixture to bum continuously on ignition. The Cleveland open cup method (ASTM D-92, IP 36) can be used to determine both flash and fire points of lubricating oils, and the Pensky-Martens closed (ASTM D-93, IP 34) and open (IP 35) flash points are also widely used. 

The flash and fire points are significant in cases where high-temperature operations are encountered, not only because of the hazard of fire but also as an indication of the volatility of an oil. In the case of used oils, the flash point is used to indicate the extent of contamination with more volatile oils or with fuels such as gasoline (ASTM D-3607). The flash point can also be used to assist in the identification of different types of base oil blend. 

Viscosity Thermal stabtiity Flash and fire points Lubricity Acidity... 

Flash and fire points. These should be sufficiently high to assure safe handling. 

Surprisingly enough, although hydraulic pump tests are easy to carry out and probably thousands have been run routinely, few usable comparisons of synthetic fl.uids are recorded in the open literature. Table 17-9 shows the results of some comparative work carried out by W. H. Mil-lett [21] with a vane pump. The polyglycol fluid gave the best all-around antiwear protection however, fluids of this type have relatively low flash and fire points, of the order of 519 to 561 K (475 to 550 F). They show good antigumming behavior, a property which is very important for servovalves with close clearances. The phosphate fluid had the poorest antiwear behavior of the three tested. 

There are heat transfer fluids (such as Paratherm OR) that resist oxidation and also offer increased thermal efficiency, significantly higher flash and fire points and longer service life. Precise uniform temperature control to 316C (600F) is provided, in dosed-loop systems where the heat transfer fluids are more than occasionally exposed to air. Typical performance characteristics are ... 

Fatty acids are much more volatile than glycerides therefore, smoke, flash, and fire points of oils depend principally... 

ASTM D 92-97. Standard test method Tot flash and fire points by Cleveland open cup. 

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