ASTM D1287-91(2002)
(Test Method)Standard Test Method for pH of Engine Coolants and Antirusts
Standard Test Method for pH of Engine Coolants and Antirusts
SIGNIFICANCE AND USE
pH is a measure of the hydrogen ion concentration and indicates whether an engine coolant, antirust, or a solution of these compounds is acidic, alkaline, or neutral.
pH is sometimes used for production quality control. It is generally desirable that engine coolants have an alkaline pH.
pH is not significant from the standpoint of predicting service life. The pH of used engine coolants or antirust solutions is not a dependable indication of either existing effectiveness or remaining life of the solution.
SCOPE
1.1 This test method covers the determination of the pH of unused engine coolants and antirusts, and used or unused aqueous dilutions of the concentrated products.
Note 1—Antirusts in solid form are not included in this test method.
Note 2—It is believed that this procedure gives all the information required for determining the pH of samples of engine coolant or antirust likely to be encountered. Should additional information on pH determinations be needed, reference should be made to Test Method E 70.
1.2 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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D1287–91 (Reapproved 2002)
Standard Test Method for
pH of Engine Coolants and Antirusts
This standard is issued under the fixed designation D1287; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 4. Significance and Use
1.1 This test method covers the determination of the pH of 4.1 pH is a measure of the hydrogen ion concentration and
unused engine coolants and antirusts, and used or unused indicates whether an engine coolant, antirust, or a solution of
aqueous dilutions of the concentrated products. these compounds is acidic, alkaline, or neutral.
4.2 pH is sometimes used for production quality control. It
NOTE 1—Antirusts in solid form are not included in this test method.
isgenerallydesirablethatenginecoolantshaveanalkalinepH.
NOTE 2—It is believed that this procedure gives all the information
4.3 pH is not significant from the standpoint of predicting
required for determining the pH of samples of engine coolant or antirust
service life. The pH of used engine coolants or antirust
likely to be encountered. Should additional information on pH determi-
nations be needed, reference should be made to Test Method E70.
solutions is not a dependable indication of either existing
effectiveness or remaining life of the solution.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Apparatus
responsibility of the user of this standard to establish appro-
5.1 The pH meter, glass electrode, and calomel electrode,
priate safety and health practices and determine the applica-
shall be as specified in the Annex.
bility of regulatory limitations prior to use.
6. Reagents
2. Referenced Documents
6.1 Purity of Reagents—Reagent grade chemicals shall be
2.1 ASTM Standards:
used in all tests. Unless otherwise indicated, it is intended that
D1176 Practice for Sampling and PreparingAqueous Solu-
all reagents shall conform to the specifications of the Commit-
tions of Engine Coolants orAntirusts forTesting Purposes
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available. Other grades may be
E70 Test Method for pH of Aqueous Solutions With the
used, provided it is first ascertained that the reagent is of
Glass Electrode
sufficiently high purity to permit its use without lessening the
3. Summary of Test Method
accuracy of the determination.
6.2 Purity of Water—Unlessotherwiseindicated,references
3.1 Asample, as received or after dilution with a specified
towatershallbeunderstoodtomeandistilledwaterorwaterof
volume of distilled water, is placed in a beaker or sample cup
equal purity. Distilled water shall be boiled thoroughly, or
and the pH measured with a pH meter and associated glass-
purged with carbon dioxide-free air, to remove carbon dioxide
saturated calomel electrode pair.
and shall be protected with a soda-lime tube or its equivalent
NOTE 3—The readings of the meter in the case of the concentrated
while cooling and in storage. The pH of the water shall be
products are not pH values according to the accepted definition, but are
between 6.2 and 7.2 at 25°C.
apparent pH values which are useful in the interpretation of the condition
of the product.
This test method is under the jurisdiction ofASTM Committee D15 on Engine
Coolants and is the direct responsibility of Subcommittee D15.04 on Chemical Reagent Chemicals, American Chemical Society Specifications, American
Properties. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Current edition approved June 15, 1991. Published October 1991. Originally listed by the American Chemical Society, see Analar Standards for Laboratory
published as D1287–53T. Last previous edition D1287–85. DOI: 10.1520/ Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
D1287-91R02. and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 15.05. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1287–91 (2002)
6.3 Standard Buffer Solutions—The buffer solutions for 9. Standardization and Testing of Electrode System in
calibrating the pH meter and electrode pair shall be prepared pH Units
from salts sold specifically for use, either singly or in combi-
9.1 The assembly shall always be standardized with one of
nation, as pH standards. The salts shall be dried for 1 h at
thestandardbuffersolutions.Asecondstandardbuffersolution
110°C before use, except in the case of borax which shall be
shall be used to check the linearity of the response of the
used as the decahydrate. The solutions with pH less than 9.5
electrodes at different pH values and to detect a faulty glass
shall be stored in chemically resistant bottles. The alkaline
electrode or incorrect temperature compensation. The two
phosphatesolutionshallbestoredinglassbottlescoatedonthe
buffer solutions selected should bracket the anticipated pH of
side with paraffin.
the solutions being tested.
9.1.1 Turn on the instrument, allow it to warm up, and
NOTE 4—Commercially available buffer tablets or prepared buffer
adjust according to the manufacturer’s instructions. Immerse
solutions may be used.
the tips of the electrodes in the standard buffer solution chosen
6.4 Potassium Hydrogen Phthalate Buffer Solution (0.05
and allow sufficient time for the temperature of the buffer
M, pH = 4.01 at 25°C)—Dissolve 10.21 g of potassium
solution and the electrodes to equalize. Set the temperature
hydrogen phthalate (KHC H O ) in water, and dilute to 1 L.
8 4 4
knob at the temperature of the buffer solution. Adjust the
6.5 Neutral Phosphate Buffer Solution (0.025 M with re-
standardization or asymmetry potential control until the meter
spect to each phosphate salt, pH = 6.86 at 25°C)—Dissolve
registersascalereading,inpHunits,equaltotheknownpHof
3.40 g of potassium dihydrogen phosphate (KH PO ) and 3.55
2 4
the standardizing buffer solution.
g of anhydrous disodium hydrogen phosphate (Na HPO)in
2 4
9.1.2 Rinse the electrodes with distilled water and touch the
water and dilute to 1 L.
tipswithadryclothortissuetoremoveexcesswater.Immerse
6.6 Borax Buffer Solution (0.01 M, pH=9.18 at 25°C)—
theelectrodesinasecondstandardbuffersolution.Thereading
Dissolve 3.81 g of disodium tetraborate decahydrate (Na B O
2 4
of the meter shall agree with the known pH of the second
7·10H O) in water, and dilute to 1 L. Protect this solution from
standard buffer solution within 60.05 unit without changing
atmospheric carbon dioxide; stopper the bottle at all times
the setting of the standardization of asymmetry potential
except when actually in use.
control. If it does not agree or if the meter gives a slow
6.7 Alkaline Phosphate Buffer Solution (0.01 M trisodium
response time and drifts, the electrode should be cleaned in
phosphate, pH=11.72 at 25°C)—Dissolve 1.42 g of anhy-
accordance with the manufacturer’s instructions.
drous disodium hydrogen phosphate (Na HPO ) in 100 mL of
2 4
9.1.3 The presence of a faulty electrode is indicated by
a0.1 Mcarbonate-freesolutionofsodiumhydroxideanddilute
failure to obtain a correct value for the pH of the second
to 1 L with water.
standard buffer solution after the meter has been standardized
6.8 Potassium Chloride Electrolyte—Prepare a saturated
with the first. A cracked electrode will often yield pH values
solution of potassium chloride (KCl) in water.
that are essentially the same for both standard buffer solutions.
7. Sampling
10. Procedure
7.1 Sample material in accordance with Practice D1176.
10.1 Make the pH determination on (1) the unused concen-
trated engine coolant or antirust (as received), or (2) any
8. Preparation of Electrode System
desired dilution, with distilled water, of the concentrated
product, or (3) used engine coolant or antirust solution. For
8.1 MaintenanceofElectrodes—Cleantheglasselectrodeat
dilute solutions, suggested engine coolant concentrations are
frequent intervals (not less than once every week during
50 and 33 volume%; antirust solution concentration should be
continual use) in accordance with the manufacturer’s instruc-
in the range of proposed usage. Prepare solutions as follows:
tions. Drain the ca
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