ASTM D1287-91(1997)e1
(Test Method)Standard Test Method for pH of Engine Coolants and Antirusts
Standard Test Method for pH of Engine Coolants and Antirusts
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 E70.
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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e1
Designation: D 1287 – 91 (Reapproved 1997)
Standard Test Method for
pH of Engine Coolants and Antirusts
This standard is issued under the fixed designation D 1287; 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 standard has been approved for use by agencies of the Department of Defense.
e NOTE—Editorial corrections were made throughout in June 1998.
1. Scope indicates whether an engine coolant, antirust, or a solution of
these compounds is acidic, alkaline, or neutral.
1.1 This test method covers the determination of the pH of
4.2 pH is sometimes used for production quality control. It
unused engine coolants and antirusts, and used or unused
is generally desirable that engine coolants have an alkaline pH.
aqueous dilutions of the concentrated products.
4.3 pH is not significant from the standpoint of predicting
NOTE 1—Antirusts in solid form are not included in this test method.
service life. The pH of used engine coolants or antirust
NOTE 2—It is believed that this procedure gives all the information
solutions is not a dependable indication of either existing
required for determining the pH of samples of engine coolant or antirust
effectiveness or remaining life of the solution.
likely to be encountered. Should additional information on pH determi-
nations be needed, reference should be made to Test Method E 70.
5. Apparatus
1.2 This standard does not purport to address all of the
5.1 The pH meter, glass electrode, and calomel electrode,
safety concerns, if any, associated with its use. It is the
shall be as specified in the Annex.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
6. Reagents
bility of regulatory limitations prior to use.
6.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
2. Referenced Documents
all reagents shall conform to the specifications of the Commit-
2.1 ASTM Standards:
tee on Analytical Reagents of the American Chemical Society,
D 1176 Practice for Sampling and Preparing Aqueous So-
where such specifications are available. Other grades may be
lutions of Engine Coolants or Antirusts for Testing Pur-
used, provided it is first ascertained that the reagent is of
poses
sufficiently high purity to permit its use without lessening the
E 70 Test Method for pH of Aqueous Solutions with the
accuracy of the determination.
Glass Electrode
6.2 Purity of Water— Unless otherwise indicated, refer-
ences to water shall be understood to mean distilled water or
3. Summary of Test Method
water of equal purity. Distilled water shall be boiled thor-
3.1 A sample, as received or after dilution with a specified
oughly, or purged with carbon dioxide-free air, to remove
volume of distilled water, is placed in a beaker or sample cup
carbon dioxide and shall be protected with a soda-lime tube or
and the pH measured with a pH meter and associated glass-
its equivalent while cooling and in storage. The pH of the water
saturated calomel electrode pair.
shall be between 6.2 and 7.2 at 25°C.
NOTE 3—The readings of the meter in the case of the concentrated
6.3 Standard Buffer Solutions—The buffer solutions for
products are not pH values according to the accepted definition, but are
calibrating the pH meter and electrode pair shall be prepared
apparent pH values which are useful in the interpretation of the condition
from salts sold specifically for use, either singly or in combi-
of the product.
nation, as pH standards. The salts shall be dried for1hat
110°C before use, except in the case of borax which shall be
4. Significance and Use
used as the decahydrate. The solutions with pH less than 9.5
4.1 pH is a measure of the hydrogen ion concentration and
1 3
This test method is under the jurisdiction of ASTM Committee D-15 on Engine Reagent Chemicals, American Chemical Society Specifications, American
Coolants and is the direct responsibility of Subcommittee D15.04 on Chemical Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Properties. listed by the American Chemical Society, see Analar Standards for Laboratory
Current edition approved June 15, 1991. Published October 1991. Originally Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
published as D 1287 – 53 T. Last previous edition D 1287 – 85. 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.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1287
shall be stored in chemically resistant bottles. The alkaline electrode or incorrect temperature compensation. The two
phosphate solution shall be stored in glass bottles coated on the 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
registers a scale reading, in pH units, equal to the known pH of
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.
tips with a dry cloth or tissue to remove excess water. Immerse
6.6 Borax Buffer Solution (0.01 M, pH = 9.18 at 25°C)—
the electrodes in a second standard buffer solution. The reading
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
a 0.1 M carbonate-free solution of sodium hydroxide and dilute
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 D 1176.
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
8.1 Maintenance of Electrodes—Clean the glass electrode at
product, or (3) used engine coolant or antirust solution. For
frequent intervals (not less than once every week during
dilute solutions, suggested engine coolant concentrations are
continual use) in accordance with the manufacturer’s instruc-
50 and 33 volume %; antirust solution concentration should be
tions. Drain the calomel electrode at least once each week and
in the range of proposed usage. Prepare solutions as follows:
fill with KCl electrolyte. Keep the electrolyte level in the
Unused engine coolant or antirust solution samples to be tested
calomel electrode above that of the solution being tested at all
should be obtained following the applicable portions of the
times. When not in use, immerse the lower halves of the
procedure outlined in Practice D 1
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