ASTM D525-00
(Test Method)Standard Test Method for Oxidation Stability of Gasoline (Induction Period Method)
Standard Test Method for Oxidation Stability of Gasoline (Induction Period Method)
SCOPE
1.1 This test method covers the determination of the stability of gasoline in finished form only, under accelerated oxidation conditions. (Warning- This test method is not intended for determining the stability of gasoline components, particularly those with a high percentage of low boiling unsaturated compounds, as these may cause explosive conditions within the apparatus. However, because of the unknown nature of certain samples, the pressure vessel assembly shall include a safety burst-disc in order to safeguard the operator.)Note 1--For measurement of oxidation stability of gasoline by measurement of potential gum, refer to Test Method D 873, or IP Test Method 138.Note 2--The precision data were developed with gasolines derived from hydrocarbon sources only without oxygenates.
1.2 The accepted SI unit of pressure is the kilo Pascal (kPa); and for temperature in C.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D 525 – 00 An American National Standard
British Standard 4347
Designation: 40/97
Standard Test Method for
Oxidation Stability of Gasoline (Induction Period Method)
This standard is issued under the fixed designation D 525; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This test method has been approved by the sponsoring aommittees and accepted by the Cooperating Societies in accordance with
established procedures.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope E 1 Specification for ASTM Thermometers
2.2 IP Standards:
1.1 This test method covers the determination of the stabil-
IP-138 Test Method for Oxidation Stability, Aviation Gaso-
ity of gasoline in finished form only, under accelerated oxida-
2 line
tion conditions. (Warning— This test method is not intended
Part IV—Petroleum and its Products
for determining the stability of gasoline components, particu-
larly those with a high percentage of low boiling unsaturated
3. Terminology
compounds, as these may cause explosive conditions within
3.1 Definitions of Terms Specific to This Standard:
the apparatus. However, because of the unknown nature of
3.1.1 break point—the point in the pressure-time curve that
certain samples, the pressure vessel assembly shall include a
is preceded by a pressure drop of exactly 14 kPa within 15 min
safety burst-disc in order to safeguard the operator.)
and succeeded by a drop of not less than 14 kPa in 15 min.
NOTE 1—For measurement of oxidation stability of gasoline by mea-
3.1.2 induction period—the time elapsed between the plac-
surement of potential gum, refer to Test Method D 873, or IP Test
ing of the pressure vessel in the bath and the break point at
Method 138.
100°C.
NOTE 2—The precision data were developed with gasolines derived
from hydrocarbon sources only without oxygenates.
4. Summary of Test Method
1.2 The accepted SI unit of pressure is the kilo Pascal (kPa);
4.1 The sample is oxidized in a pressure vessel initially
and for temperature in °C.
filled at 15 to 25°C with oxygen pressure at 690 to 705 kPa and
1.3 This standard does not purport to address all of the
heated at a temperature between 98 and 102°C. The pressure is
safety concerns, if any, associated with its use. It is the
recorded continuously or read at stated intervals until the
responsibility of the user of this standard to establish appro-
breakpoint is reached. The time required for the sample to
priate safety and health practices and determine the applica-
reach this point is the observed induction period at the
bility of regulatory limitations prior to use.
temperature of test, from which the induction period at 100°C
can be calculated. (Warning—In addition to other precautions,
2. Referenced Documents
to provide protection against the possibility of explosive
2.1 ASTM Standards:
rupture of the pressure vessel, the pressure vessel should be
D 873 Test Method for Oxidation Stability of Aviation Fuels
operated behind an appropriate safety shield.)
(Potential Residue Method)
D 4057 Practice for Manual Sampling of Petroleum and
5. Significance and Use
Petroleum Products
5.1 The induction period may be used as an indication of the
tendency of motor gasoline to form gum in storage. It should
be recognized, however, that its correlation with the formation
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.14 on Stability and Cleanliness of Liquid Fuels.
Current edition approved June 10, 2000. Published July 2000. Originally Annual Book of ASTM Standards, Vol 14.03.
published as D 525 – 39 T. Last previous edition D 525 – 99a. Available from Institute of Petroleum, 61 New Cavendish St., London WIM,
Further information can be found in the June 1978, January 1979, and June 8AR U.K.
1986 editions of the Institute of Petroleum Review. A convenient template for measuring the breakpoint is described in the paper by
Annual Book of ASTM Standards, Vol 05.01. Korb, E. L., “Induction Period Calculator,” ASTM Bulletin, No. 153, August 1948,
Annual Book of ASTM Standards, Vol 05.02. pp. 99–102.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 525
of gum in storage may vary markedly under different storage test is started. (Warning—Volatile peroxides which may have
conditions and with different gasolines. formed during a previous test may accumulate in the equip-
ment, producing a potentially explosive environment. Special
6. Apparatus
care in cleaning after each test is needed to ensure the filler rod,
stem, and needle valve are free of these peroxides.)
6.1 Oxidation Pressure Vessel, Glass Sample Container and
Cover, Accessories, Pressure Gage, and Oxidation Bath,as
10. Procedure
described in Annex A1.
10.1 Bring the pressure vessel and the gasoline to be tested
6.2 Thermometer, having a range as shown as follows and
to a temperature of 15 to 25°C. Place the glass sample
conforming to the requirements as prescribed in Specification
container in the pressure vessel and add 50 6 1 mL of test
E 1 or in the specifications for IP thermometers:
specimen. Alternatively, transfer 50 6 1 mL of test specimen
NOTE 3—Other temperature sensing devices that cover the temperature
into the glass sample container first, before placing the glass
range of interest, such as thermocouples or platinum resistance thermom-
sample container into the pressure vessel. Cover the sample
eters, that can provide equivalent or better accuracy and precision, may be
container, close the pressure vessel, and using a quick release
used in place of thermometers specified in 6.2.
air coupling introduce oxygen until a pressure of 690 to 705
Thermometer Number
kPa is attained. Allow the gas in the bomb to escape slowly in
Temperature Range ASTM IP
95 to 103°C 22C 24C
order to flush out the air originally present (Release the
pressure at a slow uniform rate through the needle valve at a
7. Reagents and Materials
rate not to exceed 345 kPa per min). Introduce oxygen again
7.1 Gum Solvent—Mixture of equal volumes of toluene and
until a pressure of 690 to 705 kPa is attained and observe for
acetone, both of which shall be of 99 % minimum purity.
leaks, ignoring an initial rapid drop in pressure (generally not
7.2 Oxygen—Commercially-available extra-dry oxygen of
over 40 kPa) which may be observed because of the solution of
not less than 99.6 % purity.
oxygen in the sample. When the rate of pressure drop does not
exceed 7 kPa in 10 min, assume the absence of leaks and
8. Sampling
proceed with the test without repressuring.
8.1 Sample in accordance with the procedure for oxidation
10.2 Place the charged pressure vessel in the vigorously
stability as described in Practice D 4057.
boiling water bath, or appropriate liquid bath equipped with
mechanical stirring, being careful to avoid shaking, and record
9. Preparation of Apparatus
the time of immersion as the starting time. Maintain the
9.1 Wash the glass sample container with gum solvent until
temperature of the liquid bath between 98 and 102°C. Observe
free from gum. Rinse thoroughly with water and immerse the the temperature to the nearest 0.1°C at intervals during the test,
sample container and cover in a mildly alkaline or neutral pH
and record the average temperature to the nearest 0.1°C as the
laboratory detergent cleaning solution. The type of detergent temperature of the test. Make a continuous record of the
and conditions for its use need to be established in each pressures in the pressure vessel, or if an indicating pressure
laboratory. The criterion for satisfactory cleaning shall be a gage is used, take pressure readings at 15-min intervals or less.
matching of the quality of that obtained with chromic acid If, during the initial 30 min of the test, a leak develops (as
cleaning solutions (or some other equivalently strong oxidizing indicated by a steady drop in pressure considerably in excess of
non-chromium containing acid cleaning solutions) on used 14 kPa in 15 min) discard the test. Continue the test until
sample containers and covers (fresh chromic acid, 6-h soaking reaching a point preceded by a pressure drop of exactly 14 kPa
period, rinsing with distilled water and drying). For this in 15 min and succeeded by a drop of not less than 14 kPa in
comparison, visual appearance and mass loss on heating the 15 min or until the induction period exceeds the product
glassware under test conditions may be used. Detergent clean- specification. (Warning—If a boiling water bath is used and
ing avoids the potential hazards and inconveniences related to the test is made in a region where the atmospheric pressure is
the handling of highly corrosive and strongly oxidizing acid consistently below normal (101.3 kPa), it is permissible to add
solutions; this procedure remains the reference cleaning prac- a liquid with higher boiling point, such as ethylene glycol, to
tice and as such may function as an alternate to the preferred the water in order to maintain the operating temperature of the
procedure, cleaning with detergent solutions.
bath in the neighborhood of 100°C. If a liquid other than water
9.2 Remove container and cover from the cleaning solution is used, be sure the liquid is compatible with the seals in the
by means of corrosion-resistant steel forceps and handle only
pressure vessel.)
with forceps thereafter. Wash thoroughly, first with tap water, 10.3 Record the number of minutes from the time the
then with distilled water, and dry in an oven at 100 to 150°C for
pressure vessel is placed in the bath until the breakpoint has
at least 1 h. been reached as the observed induction period at the tempera-
9.3 Drain any gasoline from the pressure vessel and wipe ture of the test.
the inside of the pressure vessel and pressure vessel closure, 10.4 Cool the pressure vessel to approximately room tem-
first with a clean cloth moistened with gum solvent and then perature within 30 min after removal from the bath, using
with a clean dry cloth. Remove the filler rod from the stem and ambient air or water # 35°C, before releasing the pressure
carefully clean any gum or gasoline from the stem, rod, and slowly from the pressure vessel through the needle valve at a
needle valve with gum solvent. The pressure vessel, the valve, rate not exceeding 345 kPa per minute. Wash the pressure
and all connecting lines shall be thoroughly dry before each vessel and sample container in preparation for the next test.
D 525
11. Calculation statistical examination of interlaboratory test results is as
follows:
11.1 The number of minutes from the time the pressure
vessel is placed in the bath until the breakpoint has been 13.1.1 Repeatability—The difference between two test re-
reached is the observed induction period at the temperature of sults, obtained by the same operator with the same apparatus
the test.
under constant operating conditions on identical test material,
11.2 Method of Calculation—Calculate the induction period
would in the long run, in the normal and correct operation of
at 100°C from one of the following equations: (a) When the
the test method, exceed the following values only in one case
test temperature is above 100°C:
in twenty: 5 %.
Induction period at 100°C5~IP !~1 1 0.101~t 2 100!! (1)
t a 13.1.2 Reproducibility—The difference between two single
and independent results obtained by different operators work-
(b) When the test temperature is below 100°C:
ing in different laboratories on identical test material would, in
Induction period at 100°C, min 5 ~IP !/~1 1 0.101~100 2 t !! (2)
t b
the long run, in the normal and correct operation of the test
where:
method, exceed the following values only in one case in
IP 5 induction period, min, at the temperature of the test,
t twenty: 10 %.
t 5 test temperature when above 100°C, °C, and
a
13.2 Bias—There being no criteria for measuring bias in
t 5 test temperature when below 100°C, °C.
b
these test-product combinations, no statement of bias can be
made.
12. Report
NOTE 4—The precision values given above for induction period were
12.1 Report the Induction period at 100°C, calculated as in
obtained using a boiling water bath only as the heat source. Therefore,
11.2 to the nearest 1 min.
these precision values are not necessarily applicable to induction period
12.2 If the test was stopped prior to observing the pressure
results obtained using other heat sources.
drop required in 10.2, but after the product specification was
exceeded, then report the result as being greater than N min,
14. Keywords
where N is the product specification in min.
14.1 breakpoint; gasoline; induction period; oxidation sta-
13. Precision and Bias
bility
13.1 The precision of the test method as determined by
ANNEX
(Mandatory Information)
A1. APPARATUS
A1.1 Apparatus A1.1.1.2 Other structural details, such as method of closure,
(polygonal or knurled) gasket material, and outside dimensions
A1.1.1 Pressure Vessel—The pressure vessel shall be made
are optional provided the limitations listed in A1.1.1.3 and
of corrosion-resistant steel with the inside dimensions of the
A1.1.1.4 are observed:
portion that encloses the reacting gasoline-oxygen mixture
conforming substantially to those shown in Fig. A1.1. Fig.
NOTE A1.1—Initial testing and periodic examination of the pressure
A1.1 is a composite drawing of specific pressure vessels and vessel should be carried out to ensure its fitness for service.
related apparatus for performing Test Method D 525 as made
A1.1.1.3 The pressure vessel shall be constructed to with-
by various manufacturers. As such, ranges of specific dimen-
stand a working pressure of 1240 kPa at 100°C, with an
sions have been given and are not intended to be precise.
ultimate strength at least equal to that of a pressure vessel
Pressure vessels conforming to Test Method D 525/1980-1995
constructed of 18 % (m/m) chromium, 8 % (m/m) nickel-alloy
as well as IP 40 are also suitable, but the specified burst-disc
steel. A suitable material is an alloy steel conforming to the
shall be attached. Small variations in external dimensions are
specification for 303 or 304 stainless steels.
not considered to significantly impact the results of the test, but
A1.1.1.4 The closure shall be capable of making a seal that
specific studies to document potential effects, if any, have not
will not leak when the pressure ve
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