US2999383A - Metallic tracer method for determining lubricant in engine exhaust - Google Patents
Metallic tracer method for determining lubricant in engine exhaust Download PDFInfo
- Publication number
- US2999383A US2999383A US33516A US3351660A US2999383A US 2999383 A US2999383 A US 2999383A US 33516 A US33516 A US 33516A US 3351660 A US3351660 A US 3351660A US 2999383 A US2999383 A US 2999383A
- Authority
- US
- United States
- Prior art keywords
- lubricant
- sodium
- engine
- flame
- determining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000314 lubricant Substances 0.000 title description 40
- 238000000034 method Methods 0.000 title description 9
- 239000000700 radioactive tracer Substances 0.000 title 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 27
- 229910052708 sodium Inorganic materials 0.000 description 27
- 239000011734 sodium Substances 0.000 description 27
- 238000002485 combustion reaction Methods 0.000 description 19
- 241000158728 Meliaceae Species 0.000 description 11
- 239000003921 oil Substances 0.000 description 10
- 239000000344 soap Substances 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 150000003388 sodium compounds Chemical class 0.000 description 5
- 239000010687 lubricating oil Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229910000765 intermetallic Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 238000005048 flame photometry Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 241000353097 Molva molva Species 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000011221 initial treatment Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010705 motor oil Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003460 sulfonic acids Chemical class 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
- G01N21/72—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using flame burners
Definitions
- the output of the sodium photo multiplier tube and the output of the reference photo multiplier tube is passed through separate integrators and the output of the so dium photo multiplier is fed directly into a diflerential amplifier.
- the output of the reference integrator is fed to the diflerential amplifier through a potential arrangement. In this manner the output or the differential amplifier is a direct function of the ditference between the sodium signal and the reference signal.
- the output of the differential amplifier is read directly upon the meter at the right-hand side of the drawing.
- the sodium in the lubricating oil in the form of an oil soluble sodium compound and specifically the sodium soap of mahogany acids has been found excellent for this purpose.
- Mahogany acids are sulfonic acids of unknown chemical constitution which are obtained by the initial treatment of crude petroleum with strong sulphuric acid as one of the first steps in refining the crude petroleum.
- the sodium mahoganates are obtained therefrom by a simple neutralization by a soluble alkali such as sodium hydroxide or sodium carbonate.
- the time lag is only that which can be attributed to" the sampling apparatus and aver aged about 2 seconds. Inthe case of an automobile enginewhich uses on the average of 1 gram of oil per -minute,;consumption can be estimated with an accuracy of. plus or minus five. percent.
- the process of determining the substantially instantaneous lubricant consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a known concentration of a sodium compound which is soluble in the lubricant, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, entraining this sample in a flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic of the sodium introduced into the lubricant by the sodium compound, said light intensity being indicative of the substantially instantaneous lubricant consumption.
- the process of determining, the substantially instantaneous lubricant consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a known'concentration of a metallic compound which is soluble in the lubricant, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, incorporating this sample in a stream of air, employing this air stream to support a gas flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic of the metal introduced into the lubricant by the metallic compound, said light intensity being indicative of the substantially instantaneous lubricant consumption.
Landscapes
- Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Lubricants (AREA)
Description
Sept 12,1961
RYAN
Filed June 2, 1960 OR DETERMINING SOMUM-REFERENCE QGNAL somuM REE fiGNAL mFFERENnAL SGNAL AMPUHER bNTEsRAToR1I TEsRAToR] Na CENTER somuM REFERENCE PHOTOMULTIPLIER PHOTOMULTI PLIER 5893A 6708A FILTER FILTER PHOTOMETER BURNER Q MRINLET GAS 333? SA ]NLET BY A7 METER Na RANGE FORD R BRYAN DVVENTUR.
if? 2:2 lwgw.
ATTORNEYS? United States atent Ford R. Bryan, Dearborn, Mich., assignor to Ford Motor Company, Dearborn, Mich., a corporation or Delaware Filed Juneo2, 1960, Ser. No; 33,516 8"Claims. (Cl.'73-'116) This invention teaches anovel useof thescience of flame photometry. This: application teaches especially the use of flame photometryto measure the insatntaneous oil consumption of an internal combustion engine.
I have discovered that many metallic constituents which may be present-in the lubricant of an internal combustion engine are substantially indestructible in the.combustion chamberand pass into the. exhaust streamin direct proportion to the: instantaneous .oil consumption of the engine. Flame photometry provides a convenient and highly sensitive-method of-measuring the low concentration of metal in such an exhaust-stream.
' To betterenablethis invention to be 'understood,-a single figure ofdrawing has been provided which is selfexplanatory. Aisampleof the exhaust gas-of the-engine to be tested is introducedintothe air supplyaof the photometer burner shown-at the lower left-hand corner of the drawing. The flame from this burneremits light exhibiting wave leng'ths-whichare characteristic of certain of the more easily excitable metals which maylbe incorporatedin the engine lubricant. The light from the burner is filtere'd' thr0ugh a filterconstructed to have a transmission peak -.at 5 893'Angstrom units. -'Another portion of this-light is led through a .filtenwhichiisvset .to have attransparency peak at any convenient valuewhich corresponds to no metal to' be'found in the exhaust stream. The particular filter shown has been constructed to peak at 6708 Angstrom units and corresponds to one of the frequencies which is characteristic of lithium which is absent from lubricating oils. The light from the 5893 Angstrom unit filter and that from the 6708 Angstrom unit filter is caused to fall upon respectively a sodium photo multiplier tube and a reference photo multiplier tube.
The output of the sodium photo multiplier tube and the output of the reference photo multiplier tube is passed through separate integrators and the output of the so dium photo multiplier is fed directly into a diflerential amplifier. The output of the reference integrator is fed to the diflerential amplifier through a potential arrangement. In this manner the output or the differential amplifier is a direct function of the ditference between the sodium signal and the reference signal. The output of the differential amplifier is read directly upon the meter at the right-hand side of the drawing.
While it is obvious that many metals can be incorporated in the lubricating oil to instantaneously measure the lubricating oil consumption, sodium has been found to be very satisfactory because of the intensity of the light amplification by the sodium flame. It is preferred to incorporate the sodium in the lubricating oil in the form of an oil soluble sodium compound and specifically the sodium soap of mahogany acids has been found excellent for this purpose. Mahogany acids are sulfonic acids of unknown chemical constitution which are obtained by the initial treatment of crude petroleum with strong sulphuric acid as one of the first steps in refining the crude petroleum. The sodium mahoganates are obtained therefrom by a simple neutralization by a soluble alkali such as sodium hydroxide or sodium carbonate.
As a specific example of this invention, the following experimentation was performed with a Briggs and Stratton single cylinder 4-cycle engine having a horepower PatentedSept. 12, 1961 rating of'2'.25 maximum at 3600 r.p.m. The piston displacement was 6.65 cubic inches and the crankcase capacity 1.25- pints. The engine was operated during these tests on a non-leaded gasoline. Suflicient sodium mahogany soap was added to the crankcase lubricant to give a concentration of 0.43 percent sodium in the lubricant. Tests were made at various speeds from 1000 r.p.m. to over 3000 r.p.m. with the'engine in the condition in which it was received from the factory and with the-rings-modified to progressively increase the oil consumption of the engine.
The engine as received when operating at 3000 r.p.m. upon an oil. containing 0.48 percent sodium consumed 18 grams of oil perv hour and gave a reading of 9 divisions upon the meter. The engine modified to consume 21 grams of oil per hour gave a reading of I 10 /2 divisions. Further modification of the engine to increase the oil. consumption to 40 grams per hour gave a reading of 23 divisions. Thus it can be seen that there is a subs'tantially linear relationship between oil consumption and'the meter reading. The time lag is only that which can be attributed to" the sampling apparatus and aver aged about 2 seconds. Inthe case of an automobile enginewhich uses on the average of 1 gram of oil per -minute,;consumption can be estimated with an accuracy of. plus or minus five. percent.
.1 claim:
l.-*The processtof determining the substantially instantaneous lubricant consumption of aninternal combustion enginewhich comprises establishing in the lubricant ofthe: internal'combustion engine a known concern .tration. ofametallic' compound which is soluble in the lubricant, operating-the engine, abstracting from the exhaust stream of the engine a samplewhich constitutes a knownniraction of the totalexhaust-stream, entraining this sample in a flame and photometrically determining the intensity of the light generated by the flame and having a wave length Which is characteristic of the metal introduced into the lubricant by the metallic compound, said light intensity being indicative of the substantially instantaneous lubricant consumption.
2. The process of determining the substantially instantaneous lubricant consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a known concentration of a sodium compound which is soluble in the lubricant, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, entraining this sample in a flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic of the sodium introduced into the lubricant by the sodium compound, said light intensity being indicative of the substantially instantaneous lubricant consumption.
3. The process of determining the substantially instantaneous lubricant; consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a known concentration of sodium mahogany soap, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, entraining this sample in a flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic of the sodium introduced into the lubricant by the sodium mahogany soap, said light intensity being indicative of the substantially instantaneous lubricant consumption.
4. The process of determining the substantially in stantaneous lubricant consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a concentration of sodium of about 0.48 percent in the form of sodium mahogany soap, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust streamgene training this sample in a flame and photometrically determining the intensity of light generated by the flame and having a wave length which is characteristic ofthe sodium introduced into the lubricant by the sodium mahogany soap, said light intensity being indicative of the substantially instantaneous lubricant consumption.
5. The process of determining, the substantially instantaneous lubricant consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a known'concentration of a metallic compound which is soluble in the lubricant, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, incorporating this sample in a stream of air, employing this air stream to support a gas flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic of the metal introduced into the lubricant by the metallic compound, said light intensity being indicative of the substantially instantaneous lubricant consumption.
6. The process of determining the substantially instantaneous lubricant consumption. of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a known concentration of a sodiumcompound which is soluble in the lubricant, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, incorporating this sample in a stream of air, employing this air stream to support a gas flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic of the sodium introduced into the lubricant by the sodium compound, said light intensity being indicative of the substantially instantaneous lubricant consumption.
7. The process of determining the substantially instantaneous lubricant consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a known concentration of sodium mahogany soap, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, incorporating this sample in a stream of air, employing this air'stream to support a gas flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic of the sodium introduced into the lubricant by the sodium mahogany soap, said light intensity being indicative of the substantially instantaneous lubricant consumption.
8. The process of determining the substantially instantaneous lubricant consumption of an internal combustion engine which comprises establishing in the lubricant of the internal combustion engine a concentration of sodium of about 0.48 percent in the form of sodium mahogany soap, operating the engine, abstracting from the exhaust stream of the engine a sample which constitutes a known fraction of the total exhaust stream, incorporating this sample in a stream of air, employing this air stream to support a gas flame and photometrically determining the intensity of the light generated by the flame and having a wave length which is characteristic .of the sodium introduced into the lubricant by the sodium mahogany soap, said light intensity being indicative of the substantially instantaneous lubricant consumption.
References Cited in the file of this patent UNITED STATES PATENTS 1,729,732 Wasson Oct. 1, 1929 2,664,779 White Ian. 5, 1954
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US33516A US2999383A (en) | 1960-06-02 | 1960-06-02 | Metallic tracer method for determining lubricant in engine exhaust |
| GB16327/61A GB917997A (en) | 1960-06-02 | 1961-05-05 | Improvements relating to methods for determining lubricant in engine exhaust |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US33516A US2999383A (en) | 1960-06-02 | 1960-06-02 | Metallic tracer method for determining lubricant in engine exhaust |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2999383A true US2999383A (en) | 1961-09-12 |
Family
ID=21870852
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US33516A Expired - Lifetime US2999383A (en) | 1960-06-02 | 1960-06-02 | Metallic tracer method for determining lubricant in engine exhaust |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US2999383A (en) |
| GB (1) | GB917997A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3406562A (en) * | 1966-01-14 | 1968-10-22 | Gen Motors Corp | On-line exhaust data analysis system |
| US3704952A (en) * | 1969-12-29 | 1972-12-05 | Environment One Corp | Fluid medium source tracer method |
| DE2806145A1 (en) * | 1978-02-14 | 1979-08-16 | Beckman Instruments Gmbh | PROCEDURE FOR THE EXACT DETERMINATION OF THE MEASURED VALUES IN FLAME ABSORPTION AND EMISSION PHOTOMETERS USING AN ELECTRICAL CONTROL ON A CONSTANT ENERGY LEVEL FOR COMPENSATION OF A DEVICE DRIFT |
| US4321056A (en) * | 1980-12-29 | 1982-03-23 | Cummins Engine Company, Inc. | Measurement of engine oil consumption |
| DE4305645A1 (en) * | 1993-02-24 | 1994-08-25 | Rwe Entsorgung Ag | Procedure for the determination of characteristic properties of radical forming processes |
| US20080053209A1 (en) * | 2006-08-31 | 2008-03-06 | Caterpillar Inc. | Calibration for an oil-consumption-measurement system |
| DE102020007364A1 (en) | 2020-12-03 | 2022-06-09 | Mercedes-Benz Group AG | Device for the optical analysis of flame light and method for determining particle emissions |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2350888A (en) * | 1999-06-08 | 2000-12-13 | Aea Technology Plc | Monitoring lubricating oil consumption |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1729732A (en) * | 1923-12-19 | 1929-10-01 | Robert B Wasson | Method and apparatus for testing rings and engines |
| US2664779A (en) * | 1950-06-13 | 1954-01-05 | John U White | Flame analyzer and flame source therefor |
-
1960
- 1960-06-02 US US33516A patent/US2999383A/en not_active Expired - Lifetime
-
1961
- 1961-05-05 GB GB16327/61A patent/GB917997A/en not_active Expired
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1729732A (en) * | 1923-12-19 | 1929-10-01 | Robert B Wasson | Method and apparatus for testing rings and engines |
| US2664779A (en) * | 1950-06-13 | 1954-01-05 | John U White | Flame analyzer and flame source therefor |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3406562A (en) * | 1966-01-14 | 1968-10-22 | Gen Motors Corp | On-line exhaust data analysis system |
| US3704952A (en) * | 1969-12-29 | 1972-12-05 | Environment One Corp | Fluid medium source tracer method |
| DE2806145A1 (en) * | 1978-02-14 | 1979-08-16 | Beckman Instruments Gmbh | PROCEDURE FOR THE EXACT DETERMINATION OF THE MEASURED VALUES IN FLAME ABSORPTION AND EMISSION PHOTOMETERS USING AN ELECTRICAL CONTROL ON A CONSTANT ENERGY LEVEL FOR COMPENSATION OF A DEVICE DRIFT |
| US4321056A (en) * | 1980-12-29 | 1982-03-23 | Cummins Engine Company, Inc. | Measurement of engine oil consumption |
| DE4305645A1 (en) * | 1993-02-24 | 1994-08-25 | Rwe Entsorgung Ag | Procedure for the determination of characteristic properties of radical forming processes |
| US20080053209A1 (en) * | 2006-08-31 | 2008-03-06 | Caterpillar Inc. | Calibration for an oil-consumption-measurement system |
| US7428838B2 (en) | 2006-08-31 | 2008-09-30 | Caterpillar Inc. | Calibration for an oil-consumption-measurement system |
| DE102020007364A1 (en) | 2020-12-03 | 2022-06-09 | Mercedes-Benz Group AG | Device for the optical analysis of flame light and method for determining particle emissions |
Also Published As
| Publication number | Publication date |
|---|---|
| GB917997A (en) | 1963-02-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Gibson | Nitro derivatives of polynuclear aromatic hydrocarbons in airborne and source particulate matter | |
| US2999383A (en) | Metallic tracer method for determining lubricant in engine exhaust | |
| Hilliard et al. | Nitrogen dioxide in engine exhaust | |
| Stoner et al. | Effects of structure and boiling point of oxygenated blending compounds in reducing diesel emissions | |
| Tokura et al. | Process through which soot intermixes into lubricating oil of a diesel engine with exhaust gas recirculation | |
| NO171415B (en) | PROCEDURE FOR OPERATING AN OTTO ENGINE | |
| SE7607282L (en) | METHODS AND METACHROMIC COMPOSITION FOR DETERMINATION OF LEUCOCYTS, SPECIAL BASOFILES | |
| Stephens et al. | Auto exhaust: composition and photolysis products | |
| Mckee et al. | Automobile exhaust particulates—source and variation | |
| US5162048A (en) | Additive for hydrocarbon fuels | |
| Braddock et al. | Emission patterns of diesel-powered passenger cars-Part II | |
| Laresgoiti et al. | Particle and smoke emission from a light duty diesel engine | |
| Lienesch et al. | Stirling engine progress report: smoke, odor, noise and exhaust emissions | |
| Schrenk et al. | Composition of diesel engine exhaust gas | |
| Sugiura et al. | A study of visible smoke reduction from a small two-stroke engine using various engine lubricants | |
| Bechtold et al. | Combustion characteristics of diesel fuel blends containing used lubricating oil | |
| Merrion | Effect of design revisions on two stroke cycle diesel engine exhaust | |
| Harvey et al. | Effects of a ceramic particle trap and copper fuel additive on heavy-duty diesel emissions | |
| Holtz et al. | Diesel Engines Underground: Composition of exhaust gas from engines in proper mechanical condition | |
| Aaronson et al. | Diesel odor and the formation of aromatic hydrocarbons during the heterogeneous combustion of pure cetane in a single-cylinder diesel engine | |
| Nord | Particles and unregulated emissions from CI engines subjected to emission control | |
| Cohen | Dependence of Hi-Vol measurements on airflow rate | |
| Alperstein et al. | Exhaust emissions related to engine combustion reactions | |
| Marshall et al. | Diesel emissions reinventoried | |
| Saito et al. | Surveying tests of diesel smoke suppression with fuel additives |