ASTM D7546-09

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D7546 − 09
StandardTest Method for
Determination of Moisture in New and In-Service Lubricating
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
2.1 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
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
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7546 − 09
TABLE 1 Suggested Injection Volume Based on Expected Water
7. Apparatus
Content
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 Sample Coil, for heating the sample as
it is transported from the sample inlet to the sump.
7.1.4 Sample Coil Heater, capable of maintaining the
10.2 Turn on analyzer and allow equilibration for at least 15
sample coil temperature within 1°C of the programmed tem-
min.
perature between 25°C and 200°C.
7.1.5 SampleDeliverySystem,providesprogrammablevari-
11. Calibration and Standardization
able speed injection of the sample into the coil.
11.1 Toensuretheintegrityofthetestresults,theRHsensor
7.1.6 Sump, allows for collection of the sample at the
shall be verified and calibrated using a traceable syringe.
bottom of the sample coil during testing and discharge of the
Alternatively, the RH sensor may be verified using a traceable
sample to a waste container after testing is completed.
standard solution of water in a compatible solvent. Other
7.1.7 Manifold, which provides:
suitable instrument calibration methods and standards may be
7.1.7.1 A thermally stable port for mounting and operation
used as specified by the instrument manufacturer.
of the relative humidity sensor.
7.1.7.2 Inlet and outlet ports for the carrier gas.
NOTE 1—Examples of suitable water standards include water in
7.1.8 Relative Humidity (RH) Sensor, a capacitive sensing
propylene carbonate or water in xylenes.
element that measures the relative humidity of the carrier gas.
11.2 Perform the coil heater calibration in accordance with
7.1.9 Microcontroller, which provides:
the manufacturer’s i
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