ASTM D6793-02(2007)
(Test Method)Standard Test Method for Determination of Isothermal Secant and Tangent Bulk Modulus
Standard Test Method for Determination of Isothermal Secant and Tangent Bulk Modulus
SIGNIFICANCE AND USE
Isothermal secant bulk modulus (static bulk modulus) is a property that measures the compressibility of a liquid. The greater the value, the less the compressibility of the liquid.
Isothermal secant bulk modulus is employed in the design of high performance hydraulic fluid and braking systems. High bulk modulus is desirable in that the response time of a system is faster when applied pressure more directly effects the action of the system rather than in the compression of the working liquid.
If isothermal secant bulk modulus is known as a function of pressure, the data may be used to calculate isothermal tangent bulk modulus and density as a function of pressure. The data may not, however, be used to determine isentropic (dynamic) bulk modulus. That property is usually determined from velocity of sound measurements and differs from isothermal bulk modulus by the ratio of Cp/Cv = γ (the ratio of heat capacity at constant pressure to that at constant volume for the test specimen.
SCOPE
1.1 This test method covers the determination of isothermal secant and tangent bulk modulus of liquids which are stable and compatible with stainless steel under the conditions of test.
1.2 This test method is designed to be used over the temperature range from -40 to 200°C and from ambient to 68.95 Mpa (10 000 psig). Note 1
Because of the design of the test apparatus, the upper limit of pressure which can be attained is limited by the bulk modulus of the test fluid. Pressures as high as 68.95 Mpa will not be attained for fluids of relatively low bulk modulus at the test temperature.
1.3 This test method assumes that the user is proficient in the assembly and use of medium pressure (m/p) threaded and coned fittings which are intended for use at pressures up to 137.9 Mpa (20 000 psig).
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.Note 2
Because hydraulic pressure in the test system is produced by purely mechanical means, the test method is not subject to the hazards associated with systems which are pressurized pneumatically. Even small leaks will result in immediate drop in pressure to ambient without production of a high pressure liquid stream or mist.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D6793–02 (Reapproved 2007)
Standard Test Method for
Determination of Isothermal Secant and Tangent Bulk
1
Modulus
This standard is issued under the fixed designation D6793; 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.
1. Scope D235 Specification for Mineral Spirits (Petroleum Spirits)
(Hydrocarbon Dry Cleaning Solvent)
1.1 This test method covers the determination of isothermal
D4057 Practice for Manual Sampling of Petroleum and
secant and tangent bulk modulus of liquids which are stable
Petroleum Products
andcompatiblewithstainlesssteelundertheconditionsoftest.
D4177 Practice for Automatic Sampling of Petroleum and
1.2 This test method is designed to be used over the
Petroleum Products
temperature range from -40 to 200°C and from ambient to
E300 Practice for Sampling Industrial Chemicals
68.95 Mpa (10000 psig).
NOTE 1—Because of the design of the test apparatus, the upper limit of 3. Terminology
pressure which can be attained is limited by the bulk modulus of the test
3.1 Definitions:
fluid. Pressures as high as 68.95 Mpa will not be attained for fluids of
3.1.1 isothermal secant bulk modulus—theproductoforigi-
relatively low bulk modulus at the test temperature.
nal fluid volume and the slope of the secant drawn from the
1.3 This test method assumes that the user is proficient in
origin to any specified point on the plot of pressure versus
the assembly and use of medium pressure (m/p) threaded and
volume change divided by volume at constant temperature.
coned fittings which are intended for use at pressures up to
3.1.2 isothermal tangent bulk modulus—theproductoffluid
137.9 Mpa (20000 psig).
volume at any specified pressure and the partial derivative of
1.4 This standard does not purport to address all of the
fluid pressure with respect to volume at constant temperature.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 Determination of Isothermal Secant Bulk Modulus:
bility of regulatory limitations prior to use.
4.1.1 A piston in the form of a medium pressure valve is
forced into a chamber which is liquid-filled. The pressure
NOTE 2—Because hydraulic pressure in the test system is produced by
purely mechanical means, the test method is not subject to the hazards created by the insertion of the piston is measured.
associated with systems which are pressurized pneumatically. Even small
4.2 A system constant V/DV is determined by use of a
leaks will result in immediate drop in pressure to ambient without
standard of known bulk modulus as follows:
production of a high pressure liquid stream or mist.
– –
V B B
i i
2. Referenced Documents 5 5 (1)
S D
DV P ~P 2 P !
n o
2
2.1 ASTM Standards:
where:
–
= isothermal secant bulk modulus,
B
i
1
This test method is under the jurisdiction of ASTM Committee D02 on
P = pressure at the origin before insertion of the piston,
o
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee
and
D02.L0.07 on Engineering Sciences of High Performance Fluids and Solids.
P = pressure of the system at insertion of piston to
n
Current edition approved May 1, 2007. Published June 2007. Originally
Position n.
approved in 2002. Last previous edition approved in 2002 as D6793–02. DOI:
10.1520/D6793-02R07.
2 NOTE 3—V/DV is thus a constant determined by system volume and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
piston displacement only. It is independent of temperature and when
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
known, can be used to determine isothermal secant bulk modulus from
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. pressure data obtained for various degrees of piston insertion.
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D6793–02 (2007)
4.3 Isothermal tangent bulk modulus and sample density, if
desired, may be determined from isothermal secant bulk
modulusdatadeterminedasafunctionofpressurebyuseofthe
calculations in Section 12.
5. Significance and Use
5.1 Isothermalsecantbulkmodulus(staticbulkmodulus)is
a property that measures the compressibility of a liquid. The
greater the value, the less the compressibility of the liquid.
5.2 Isothermal secant bulk modulus is employed in the
design of high performance hydraulic fluid and braking sys-
tems. High
...
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