Variables in lamp Design That Affect Smoke Point FREDERICK W. R A K O W S K Y and RUSSELL A. HUNT, JR. Research Department, Standard O i l Co. (Indiana), Whiting, Ind.
sidered the major ones affecting smoke point. Each was studied over a range while the other three were held constant, The data were used to design a lamp that best distinguishes between fuels and is easy to operate in routine use.
-4 study has been made of the physical variables of a wick-type lamp that affect the smoke-point test of petroleum distillates. Wick diameter, chimney diameter, chimney height, and relative height of air screen and wick guide affect smoke point. Lamp dimensions that gave maximum distinction between fuels were used in designing a new lamp with an improved mechanism that increases precision. The new lamp correlates well with the Factor lamp and the widely used Institute of Petroleum lamp. It offers a more precise way of determining the burning quality of jet fuels and heating oils.
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EXPERIMENTAL
HE smoke-point test is becoming increasingly important
as a means of measuring the burning quality of petroleum distillates. The smoke point is the height of the tallest flame that can be produced without smoking in a test lamp. It has been used to define the quality of kerosine since the Institute of Petroleum introduced a standard lamp in the early 1930's (5, IO). More recently, it has been used as a measure of the sooting tendency of heating oils (11) and jet-aircraft fuels ( 7 ) . The higher the smoke point, the better the burning quality and the lower the sooting tendency. To make the test most useful, the lamp should be designed to provide maximum sensitivity in the range where fuel-quality requirements fall. Several different lamps have been used in smoke-point studies. The wick lamp from the Weber spectrophotometer was used by Kewley and Jackson (6) and was later adapted by the Institute of Petroleum ( 5 ) . The Factor lamp was developed by Davis and later modified by Terry and Field (9) to improve its sensitivity. A wickless lamp built by Clarke Hunter, and Garner ( 3 ) was based on the observation that a change in burning area changes flame height; although sensitive, it is too cumbersome for routine use. Lamps built by Schalla and McDonald (8) were used to compare diffusion flames fed with gaseous hydrocarbons from an open port with flames fed from liquids via wicks; such lamps are not adaptable to routine testing. Today, only the Institute of Petroleum lamp is widely used in determining smoke points. Although the effects of some lamp design variables have been investigated in a burner using gaseous benzene ( d ) , no systematic study of the effect of these variables on sensitivity in a wick-type lamp seems to have been undertaken in earlier work. Such a study with wick-type lamps is discussed here. Four variableswick diameter, chimney height, chimney diameter, and the relation of air-screen height to wick-guide height-were con-
Table I.
Inspections of Test Fuels
Cycle Oil from Catalytic Cracking 32.7 438 462 497 553 587
Sulfur, mt. %
0.372
Light Virgin Gas Oil Virgin S a p h t h a 41.8 330 364 432 510 563 0.374
49.8 306 324 334 356 380 0.017
An experimental smoke-point apparatus, shown in Figure 1, v a s designed for maximum flexibility. It consists mainly of two vertical concentric tubes, plus chimney, air screen, and oil holder. The lower tube can be moved by a rack and pinion, Thus, a wick fastened in the lower tube can be moved through the upper tube to adjust flame height. Tubes with inside diameters of 6.4 mm. ( I / d inch), 8.0 mm. (:/,E inch), and 9.5 mm ( 3 1 8 inch) accommodate oil wicks of these sizes. White felt wicking is used, rather than woven or sewn wicking, because it is uniform and easy to trim ( 4 ) . The lower portion of the wick is immersed in an oil holder containing the test fuel.
LOWER
WICK
OIL HOL
Figure 1.
Experimental smoke-point lamp
The upper tube is fastened to a circular plate, which supports the chimney and air screen. Glass chimneys 1.8,2.2,2.6, 3.0, and 3.4 cm. in diameter and 12.7 cm. (5 inches), 20.3 cm. (8 inches), 27.9 cm. (11 inches), and 35.5 cm. (14 inches) tall are used. To admit air for the flame, cylindrical screens of 20-mesh stainless steel 1.9 cm. ( 3 / 4 inch) high are provided for all chimney diameters, and with heights of 1.27 cm. ( I / * inch), 2.54 cm. (1 inch), 3.18 cm. (11/4 inches), and 3.81 em. ( 1 1 / 2 inches) for the 22-mm. chimney. Three test fuels were chosen to represent components of fuels that might have to meet a smoke-point specification; inspection data are shown in Table I. The cycle oil from catalytic cracking and the light virgin gas oil represented the two major grades of heating oils; the virgin naphtha represented a light component 1583
ANALYTICAL CHEMISTRY
1584 200
I
of jet fuel. A fourth fuel was an equal mixture by volume of n-decane, n-dodecane, n-tetradecane, and n-heuadecane and served as a reference fuel of high smoke point. This blend of alkanes was included to represent the extreme that might be encountered in testing hydrocarbons. The procedure used to determine smoke points has been detailed ( 4 ) . The lamp v a s lit, adjusted to give a smokeless flame, and allowed to burn 10 minutes to reach equilibrium. The flame was turned up until it smoked and then was lowered don-ly until the smoky tail just disappeared. The height of the flame at this point was taken as the smoke point. Each smoke point \T as checked by two independent observers.
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Figure 2.
Effect of wick diameter
Chimney diameter, 22 mm. Chimney height, 20.3 om. Screen height, 2.54 cm.
Analysis of the data obtained showed that each of the four variables studied had an influence on smoke point. The data formed the basis for 16 graphs that showed how each variable responded to controlled changes in the other lamp dimensions. With certain combinations of dimensions, some fuels could not be made to smoke. HoTever, the trend of the effect of each variable was similar for all values assigned to the fixed dimensions. The effect of nick diameter is illustrated by Figure 2. The first increase in nick diameter spread the smoke points. However, the 9.5-mm. wick seems to be too large to permit complete combustion; the gas oil and alkanes showed lower smoke points and the cycle oil could not be burned without smoking. The effect of chimney height is shonn in Figure 3. Increasing it from 12.7 to 27.9 cm. spreads the emoke-point values. Above 28 cm., the chimney seems to cause enough air flow to hold doxm the smoke point of the alkanes and prevent the naphtha from smoking. The effect of chimnej diameter is shown in Figure 4. Increasing the chimney diameter brought the smoke-point values of the
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CHIMNEY D I A M E T E R M M .
Figure 4. Wick diameter, 8 mm. Chimney diameter, 22 mm. Screen height, 2.54 cm.
Effect of chimney diameter Wick diameter, 8 mm. Chimney height, 20.3 cm. Screen height, 1.9 cm.
35
1585
V O L U M E 28, NO. 10, O C T O B E R 1 9 5 6
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of height of screen
Figure 6. Indiana smokepoint lamp
:r, 8 mm. :ht. 20.3 om. meter. 22 mm.
himneys narrower than 2.2 cm. bphtha much like longer chimneys the alkane curve passes through :r increases, the 2.2-cm. chimney e for the three fuels. I of the top of the air screen rolade is shown in Figure 5. If the d screen height is kept constant, ried between 1and 5 cm. without wick guide 2.54 cm. high was the height of the air screen until spreads the three fuels. Further md cause the flames to be poorly I by the larger circles. With the the alkanes could not he deter-
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Fed that 8. lamp with an 8-mm. t and 2.2 cm. in diameter, a wick :reen 2.5 cm. high would give the
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e Indiana smoke-paint lamp has in the burning section are those It that the air-screen height has ches) to give taller flames in the in Figure 6. Use of an oil holder e of Petroleum smoke lamp ( 5 ) and wicks. knob moves the wick only 1 mm. tft on which rides a runner carryThis mechanism permits deter-
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Figure 7.
Smoke points obtained with three lamps
mination of smoke paints more precisely than W & B heretofore possible. The procedure for obtaining smoke points with the new lamp used in the present study is essentially that of the ASTM tenta-
ANALYTICAL CHEMISTRY
1586 tive method of test for smoke point of jet fuels (1). Repeatability is good; duplicate determinations by the same operator do not differ by more than 1 mm. Different operators using different lamps agree within 2 mm. The sensitivity of the new lamp was compared with those of the Institute of Petroleum and Factor lamps on widely differing fuels (Figure 7 ) . Blends of No. 2 fuel oils provided low smoke points. No. 1 fuel oils, kerosines, jet fuels, and gasolines covered the intermediate range. Individual alkanes provided high smoke points. The new lamp is much more sensitive to fuel quality than the Institute of Petroleum lamp. It doubles the spread a t low values and quadruples it a t intermediate values. The Institute of Petroleum lamp does not differentiate among fuels of high smoke point, as it was designed for the lower range. The new lamp is slightly more sensitive than the Factor lamp. The spread is increased by about 10%. The dimensions of the Factor lamp were evidently selected with some knowledge of how they would affect smoke point. However, the increased precision of the new lamp gives it a major advantage. CONCLUSION
The increased emphasis on reducing carbon deposition in jet engines has greatly increased the need for better methods of specifying fuel burning quality. The improved lamp will help meet this need and should prove useful in specifying burning quality of kerosine and home-heating oils. If this lamp finds
acceptance in the industry, arrangements will be made to make it available through normal suppliers under license. ACKNOWLEDGMENT
The valuable assistance of George Hajduk in this study is acknowledged. LITERATURE CITED
Am. Soc. Testing Materials, Philadelphia, “Standards on Petroleum Products and Lubricants,” p. 753, 1954. ( 2 ) Clark, T. P., “Influence of External Variables on Smoking of Benzene Flames,” Natl. Advisory Comm. Aeronautics,
(1)
NACA RM E52G24 (1952). (3)
Clarke, A. E., Hunter, T. G., Garner, F. H., J . Inst. Petroleum 32,627-42 (1946).
Hunt, R. h.,I n d . Eng. Chem. 45, 602 (1953). ( 5 ) Institute of Petroleum, London, “Standard Methods for Testing Petroleum and Its Products,” p. 434, 1955. ( 0 ) Kewley, J., Jackson, J. S., J . Inst. Petroleum Technol. 13, 364 (4)
(1 927).
(7) Alilitarg Specification MIL-F-5624C,
18 May 1955, Fuel, Aircraft Turbine and Jet Engine Grades JP-3, JP-4, Jp-5. (8) Schalla, R. L., bIcDonald, G. E., Ind. Eng. C h m . 45, 1497-500 (1953). (9) Terry, J. B., Field, E., IND.ENG.CHEX.,A N A L . ED. 8, 293 (1936). (10) Woodrow, W. A,, V o r l d Petroleum Congr. (London), Proc. 2 , 732 (1933). (11) Worrall, G. I., Ind. Eng. Chem. 46, 2178 (1954). RECEIVEDfor review February 8, 1956. Accepted J u n e 21, 1956. Division of Petroleum Chemistry, 129th Meeting, ACS, Dallas, Tex., April 1956.
Identification of Synthetic Fibers by Micro Fusion Methods DONALD G. GRABAR and RITA HAESSLY Central Laboratory, lndurtrial Rayon Corp., Cleveland, Ohio
A scheme for the identification of synthetic fibers by the use of micro fusion methods is based upon the melting point of the fiber, the eutectic temperature of the fiber with p-nitrophenol as a reference compound, and the characteristic behavior observed during the heating and cooling of the fibers. Observations are made using a hot stage on a polarizing microscope. Reproducible melting points are obtained by using a silicone oil as a mounting liquid for the fibers to exclude air from the fibers while heating and to improve the microscopic image. Tabulated micro fusion data are given for thirteen synthetic fibers.
T
HE technical literature abounds in descriptions of various techniques for the identification of textile fibers. These methods are based principally on microscopical observations of morphological characteristics visible in cross section and longitudinal views, together with supplementary tests such as staining, solubility, and refractive index (1, $, 4). Although in favorable cases each of these techniques may afford positive identification in itself, in the majority of cases one or more of the tests must be used to confirm the results obtained by another. The method described here, using micro fusion methods, is selfsufficient in most instances, but in some cases also must be confirmed by one or more of the other tests. However, it presents advantages over previously described techniques in being more widely applicable to both dyed and undyed, bright and dull, and filament and staple fibers. It is also generally faster and more
positive in distinguishing between chemically similar fiberse.g., Nylon type 6 and Kylon type 66. Although the fibers used in the test are destroyed, only very small samples are required. Micro fusion methods have heretofore been applied only to monomeric systems. The general technique was originally developed by the Koflers in Germany ( 3 ) ,and extended and promoted in this country mainly through the efforts of McCrone (6) and coworkers. The identification of an unknown is based upon the use of a hot stage and microscope for determining (a)the melting point of the compound, ( b ) the eutectic melting point of the compound with a reference compound, (c) the refractive index of the melt, and ( d ) characteristic behavior observed during the heating and cooling of the compound. The determination of refractive index is unnecessary in the application of the technique described herein. Melting points have been generally considered of limited use in fiber identification for two reasons: synthetic fibers which melt usually do so nonreproducibly over an appreciable temperature range, and many of the synthetic fibers decompose completely before their melting point is reached. The first objection arises primarily from the common method of measuring fiber melting points, the copper block method. By this method a sticking temperature or softening point is observed, which, although useful in indicating use properties of the fibere.g., maximum ironing temperature-is of little analytical value High polymeric fibers invariably are incompletely crystallized When the fiber is heated, this incomplete crystallization causes a softening of the amorphous portions before actual melting of the crystalline parts occurs. Furthermore, a range of crystalline
