ASTM D7546-09
(Test Method)Standard Test Method for Determination of Moisture in New and In-Service Lubricating Oils and Additives by Relative Humidity Sensor
Standard Test Method for Determination of Moisture in New and In-Service Lubricating Oils and Additives by Relative Humidity Sensor
SIGNIFICANCE AND USE
Knowledge of the water content of lubricating oils, additives, and similar products is important in the manufacture, purchase, sale, transfer, or use of such petroleum products to help in predicting their quality and performance characteristics.
For lubricating oils, the presence of water can lead to premature corrosion and wear, an increase in the debris load resulting in diminished lubrication and premature plugging of filters, impedance to the effect of additives, and undesirable support of deleterious bacterial growth.
SCOPE
1.1 This test method covers the quantitative determination of water in new and in-service lubricating oils and additives in the range of 10 to 100 000 mg/kg (0.001 to 10% wt./wt.) using a relative humidity (RH) sensor. Methanol, acetonitrile, and other compounds are known to interfere with this test method.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 Warning—Samples tested in this test method can be flammable, explosive, and toxic. Use caution when handling them before and after testing.
1.4 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: D7546 − 09
StandardTest Method for
Determination of Moisture in New and In-Service Lubricating
1
Oils and Additives by Relative Humidity Sensor
This standard is issued under the fixed designation D7546; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope increments from 25°C to 200°C. The coil is maintained at a
constant temperature for the duration of the test.As the sample
1.1 This test method covers the quantitative determination
travels down the coil, an opposing dry inert gas carries the
of water in new and in-service lubricating oils and additives in
thermally evolved moisture past a relative humidity sensor.
therangeof 10to100 000 mg/kg (0.001 to 10% wt./wt.)using
The sensor signal is integrated over time to provide a measure-
a relative humidity (RH) sensor. Methanol, acetonitrile, and
ment of total mass of water in the sample.
other compounds are known to interfere with this test method.
4.2 The sample injection may be done either by mass or by
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this volume.
standard.
4.3 This test method utilizes anhydrous compressed gas or
1.3 Warning—Samples tested in this test method can be
ambient air passed through a desiccant to prevent contamina-
flammable, explosive, and toxic. Use caution when handling
tion from moisture present in the atmosphere.
them before and after testing.
4.4 Viscous samples can be analyzed by preheating them to
1.4 This standard does not purport to address all of the
place them in a more fluid state allowing them to be drawn into
safety concerns, if any, associated with its use. It is the
a syringe, or by dissolving them in a compatible anhydrous
responsibility of the user of this standard to establish appro-
solvent. Care should be taken to minimize time spent preheat-
priate safety and health practices and determine the applica-
ing samples to prevent moisture loss.
bility of regulatory limitations prior to use.
2. Referenced Documents 5. Significance and Use
2
2.1 ASTM Standards:
5.1 Knowledge of the water content of lubricating oils,
D4175 Terminology Relating to Petroleum, Petroleum
additives,andsimilarproductsisimportantinthemanufacture,
Products, and Lubricants
purchase, sale, transfer, or use of such petroleum products to
helpinpredictingtheirqualityandperformancecharacteristics.
3. Terminology
5.2 For lubricating oils, the presence of water can lead to
3.1 For definitions of terms used in this test method, refer to
premature corrosion and wear, an increase in the debris load
Terminology D4175.
resulting in diminished lubrication and premature plugging of
4. Summary of Test Method
filters, impedance to the effect of additives, and undesirable
support of deleterious bacterial growth.
4.1 An aliquot of sample is injected onto a heated stainless
steel coil. The temperature of the coil is programmable in 1°C
6. Interferences
1
This test method is under the jurisdiction of ASTM Committee D02 on
6.1 Methanol and acetonitrile are known to interfere with
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
the determination of moisture by this test method. These
D02.96.02 on Chemistry for the Evaluation of In-Service Lubricants.
substances contribute to a high bias in the final results. More
Current edition approved Oct. 1, 2009. Published November 2009. DOI:
10.1520/D7546-09.
generally,someshort-chainedpolarmoleculesmimictheeffect
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
of water at the RH sensor resulting in a positive interference.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Strong polar solvents, such as n-methyl-pyrrolidone, can se-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. verely damage the RH sensor.
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D7546 − 09
TABLE 1 Suggested Injection Volume Based on Expected Water
7. Apparatus
Content
3
7.1 Moisture Analyzer, an apparatus that consists of:
Expected Water Concentration, % Sample Volume, mL
7.1.1 FlowRegulator, capable of maintaining the carrier gas
Less than 0.02 5
0.02 to 0.025 4
flow rate within the manufacturer’s specified conditions.
0.025 to 0.035 3
7.1.2 Flow Meter, capable of measuring the carrier gas flow
0.035 to 0.050 2
rate within the manufacturer’s specified conditions.
Greater than 0.05 1
7.1.3 Stainless Steel Sam
...
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