Smoke point, defined

Specifications for gas turbine fuels prescribe test limits that must be met by the refiner who manufactures fuel however, it is customary for fuel users to define quality control limits for fuel at the point of delivery or of custody transfer. These limits must be met by third parties who distribute and handle fuels on or near the airport. Tests on receipt at airport depots include appearance, distfllation, flash point (or vapor pressure), density, freezing point, smoke point, corrosion, existing gum, water reaction, and water separation. Tests on delivery to the aircraft include appearance, particulates, membrane color, free water, and electrical conductivity. 

The flash point defines the temperature at which the decomposition products formed from frying oils can be ignited. This temperature ranges from 275°C to 330°C for different oils and fats (Table 13). An increase in the content of unsaturated fatty acids usually decreases the flash and smoke points (60). 

Kerosene can vary widely in its burning quality as measured by carbon deposition, smoke formation, and flame radiation. This is a function of hydrocarbon composition—paraffins have excellent burning properties, in contrast to those of the aromatics (particularly the polynuclear aromatic hydrocarbons). As a control measure the smoke point test (ASTM D-1322, IP 57) gives the maximum smokeless flame height in millimeters at which the fuel will burn in a wick-fed lamp under prescribed conditions. The combustion performance of wide-cut fuels correlates well with smoke point when a fuel volatility factor is included, because carbon formation tends to increase with boiling point. A minimum smoke volatility index (SVI) value is specified and is defined as ... 

Smoke point of a turbulent flame is defined as the critical fuel mass flow rate (CFMFR) beyond which the flame does not smoke. Goh [88] studied the effects of nitrogen dilution on the smoke point characteristics of propylene diffusion flames in crossflow. Figure 29.20 shows the variation of diluent mass flow rate with fuel... 

The smoke point is another measure of the tendency of a fuel to produce smoke and this quantity, like SEA, is related to the chemical composition and structure of the fuel. The smoke point is defined as the minimum fuel mass flow rate at which smoke first escapes from the tip of a laminar diffusion flame (see Fig. 2), ie, the residence time of the smoke in the combustion zone becomes too short to effect complete oxidation. The results of the smoke point test are qualitatively similar to the SEA data in Table 15 with respect to chemical structure and smokeforming tendency. In particular, it is found that the smoke-forming tendency, as determined by smoke point measurements, is lowest for oxygenated fuels (alcohols, aldehydes, esters, ethers) and increases through the series alkanes, branched alkanes, alkenes, and aromatics. 

Four important tests which are used to characterize an engine fuel are the spontaneous ignition temperature (SIT), flash point, fire point, and smoke point. These tests are standardized, and specialized fuels have specific requirements as defined by these tests. The SIT is dependent on the composition of the fuel and the conditions of the walls of the cylinder. Diesel fuels require low SIT with short delay times of the order of 1-2 ms. The SIT of heptane (CN = 60) is 330°C, whereas benzene with CN = —10 has a SIT of 420°C. 

Bias—The procedure in Test Method D 1322 for measuring the smoke point of kerosines and aviation turbine fuels has no bias because the value of the smoke point can only be defined in terms of a test method. 

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. 

The capture velocity of a hood is defined as the air velocity created by the hood at the point of contaminant generation. The hood must generate a capture velocity sufficient to overcome opposing air currents and transport the contaminant to the hood. For enclosing hoods, capture velocity is the velocity at the hood opening. In this case, the velocity must be sufficient to keep the contaminant in the hood. In practice, hood shape and the influence of crossdrafts on the measured capture velocity have to be considered. All three velocity components should be measured and used to calculate the magnitude and direction of the total velocity. Other methods used, not as good as the previous one, are to measure the velocity with a directional velocity sensor towards the hood or to measure the net velocity by an omnidirectional velocity sensor. In the last method the main airflow direction should be viewed and evaluated by means of a smoke test (see Sections 10.2.1 and 10.2.2.1). 

In an ideal situation the parameters used to define furniture should be ignition resistance and the rate of generation of heat, smoke and toxic gases. Tests to do this with actual or mock-up full sized furniture are not yet available as final specifications but the Nordtest (28) and NBS furniture calorimeters (29) represent scientific methods while room/ corridor rigs, typically UK DOE PSA FR5 and 6 of 1976 (5) (6) were originally used but are less satisfactory from a scientific point of view. The Californian (30) and Boston tests (31) for public area furniture are essentially simple room tests and are similar in principle to DOE, PSA, FR5 and 6 although the latter do not have pass/fail criteria. Bench scale rate of heat release tests include the NBS cone (29) which, with a code of practice represent a possible alternative but the rate of burning of... 

Move the sample tube in toward the smoke source from all directions at this level to the point where particle counts show a sudden and rapid rise to high levels (lO per cubic foot). This defines the envelope of dispersion away from the smoke source and demonstrates the airflow parallelism control of the room. Repeat for all grid areas. Prepare a diagram showing grid areas and corresponding dispersion envelopes. 

Having defined the types of commonly used carbon nucleophiles and carbon electrophiles, it would seem that if you react any of the carbon nucleophiles (electron donors) with any of the carbon electrophiles (electron acceptors), then a carbon-carbon bond should be formed. While this is theoretically true, it is unworkable from a practical point of view. If, for example, a carbanion nucleophile was reacted with a cationic electrophile, it is unlikely that the desired carbon-carbon bond formation would be detected, even after the smoke cleared. Or if a silyl enol ether nucleophile was reacted with an a, /f-unsaturated ester, no reaction could be observed to take place in any reasonable time frame. 

Research in the field of combustion toxicology is primarily concerned with items 1, all of which are related to the toxic potency of the fire gas effluent. Toxic potency is defined by ASTM as a quantitative expression relating concentration (of smoke or combustion gases) and exposure time to a particular degree of adverse physiological response, for example, death on exposure of humans or animals. This definition is followed by a discussion, which states, The toxic potency of smoke from any material or product or assembly is related to the composition of that smoke which, in turn, is dependent upon the conditions under which the smoke is generated. One should add that the LCso is a common end point used in laboratories to assess toxic potency. In the comparison of the toxic potencies of different compounds or materials, the lower the LC50 (i.e., the smaller the amount of material necessary to reach the toxic end point), the more toxic the material is. 

To begin with, let me define my terms. From the military point of view, the term chemical weapons includes not only the well-known war gases as they are commonly called, but also the use of flame and smoke on the battlefield. I shall confine myself entirely to the war gases. This term in itself is inaccurate, as many of the chemical compounds concerned are not gases but rather liquids or even solids under ordinary conditions. However, the term has the sanction of established usage everyone knows what it means. It refers simply to the large-scale use of chemicals on the battlefield for their direct casualty-producing effect on the individual soldier after they have come in contact with his skin or been absorbed into his body. 

The smoke and combustion gases are drawn to a sampling point, where the smoke measurement is made with a low intensity helium-neon laser beam projected across the diameter of the duct. The smoke data are reported as the specific extinction area. This is defined as the area (m ) of the smoke generated per mass (kg) of specimen decomposed thus the units are m /kg. Specimens used as 100 mm x 100 mm and up to 50 mm thick. The heat flux can be varied from 1 to lOOkW/m, with horizontal or vertical specimen orientation. 

Non-invasive PTR-MS sampling for medical applications has been used for the analysis of urine from non-smokers and habitual smokers [ 1 ]. Earlier breath analysis studies had already demonstrated that the acetonitrile level is elevated in the breath of smokers. The aim of this later study was to ascertain whether acetonitrile could also be detected in the headspace of urine and, if so, whether elevated levels are found for smokers. The study included 101 volunteers (57 men and 44 women) and the conclusion was that elevated acetonitrile levels are found in the urine of smokers. The mean (standard deviation) acetonitrile concentration in the headspace above urine of 46 non-smokers was 3.7 (1.8) ppbv, whereas for heavy smokers (defined as someone who smokes more than 30 cigarettes per day) it was found to be 28.0 (5.4) ppbv. An interesting point raised by the authors of this work was whether the increased levels of acetonitrile in the urine of smokers is a contributing factor leading to the known increase in bladder cancer for smokers compared to non-smokers. 

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