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Description / Abstract:
These test methods cover four procedures for determination of
the permeability [relative permeability]2 of materials
having a permeability not exceeding 6.0.
The test methods covered are as follows:
Test Method 1—Fluxmetric Method is suitable for
materials with permeabilities between 1.0 and 4.0. This method
permits the user to select the magnetic field strength at which the
permeability is to be measured.
Test Method 2—Permeability of Paramagnetic Materials
has been eliminated as an acceptable method of test.
Test Method 3—Low Mu Permeability Indicator is suitable
for measuring the permeability of a material as "less than" or
"greater than" that of calibrated standard inserts with
permeability between 1.01 and 6.0, as designated for use in a
Low-Mu Permeability Indicator.3 In this method, a small
volume of specimen is subjected to a local magnetic field that
varies in magnitude and direction, so it is not possible to specify
the magnetic field strength at which the measurement is made.
Test Method 4—Flux Distortion is suitable for materials
with permeability between 1.0 and 2.0. In this method, a small
volume of specimen is subjected to a local magnetic field
that varies in magnitude and direction, so it is not possible to
specify the magnetic field strength at which the measurement is
made.4
Test Method 5—Vibrating Sample Magnetometry is suitable
for materials with permeability between 1.0 and 4.0. This test
method permits the user to select the magnetic field strength at
which the permeability is to be measured.
Materials typically tested by these methods such as austenitic
stainless steels may be weakly ferromagnetic. That is, the magnetic
permeability is dependent on the magnetic field strength. As a
consequence, the results obtained using the different methods may
not closely agree with each other.When using Methods 1 and 5, it is
imperative to specify the magnetic field strength or range of
magnetic field strengths at which the permeabilities have been
determined.
The values and equations stated in customary (cgs-emu and
inch-pound) or SI units are to be regarded separately as standard.
Within this standard, SI units are shown in brackets except for the
sections concerning calculations where there are separate sections
for the respective unit systems. The values stated in each system
may not be exact equivalents; therefore, each system shall be used
independently of the other. Combining values from the two systems
may result in nonconformance with this standard.
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.
2 Test Methods 1 and 5 actually measure magnetic
susceptibility. The permeability (μ) [relative permeability (μr)]
is related to the susceptibility (κ) by the equations:
The term permeability has been retained in these test methods
because of its widespread commercial and technological usage.
3 The sole source of supply of the apparatus known to
the committee at this time is Low-Mu Permeability Indicator,
manufactured by Severn Engineering Co., Inc., 555 Stage Rd., Suite
1A, Auburn, AL 36830, http://www.severnengineering.com. (Indicators
can be returned for recalibration.) If you are aware of alternative
suppliers, please provide this information to ASTM International
Headquarters. Your comments will receive careful consideration at a
meeting of the responsible technical committee,1 which
you may attend.
4 The sole source of supply of the apparatus known to
the Committee at this time is the Magnetoscop manufactured by
INSTITUT DR. POERSTER GmbH Co. KG. in Laisen 70, 72766,
Reutlingen, Germany. (Probes can be returned for calibration.) If
you are aware of alternate suppliers, please provide this
information to ASTM International Headquarters. Your comments will
receive careful consideration at a meeting of the responsible
technical committee,1 which you may attend.