ASTM-A698 Standard Test Method for Magnetic Shield Efficiency in Attenuating Alternating Magnetic Fields

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Standard Test Method for Magnetic Shield Efficiency in Attenuating Alternating Magnetic Fields



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1.1 This test method covers the means for determining the performance quality of a magnetic shield when placed in a magnetic field of alternating polarity.

1.2 This test method provides a means of evaluating and grading magnetic shielding materials to determine their suitability for use in the production of magnetic shields.

1.3 This test method shall be used in conjunction with and shall conform to the requirements of Practice A34/A34M.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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 non-conformance with the standard.

1.5 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.

Significance and Use

5.1 This test method provides an easy, accurate, and reproducible method for determination of shielding factors (attenuation ratios) in simple alternating magnetic fields.

5.2 Since the sensing or pickup coil is of finite size, the measured shielding factor tends to be the average value for the space enclosed by the coil. Due care is required when interpreting results when the coil is located near an opening in the shield.

5.3 This test method is suitable for design, specification acceptance, service evaluation, quality assurance, and research purposes on magnetic shields.

5.4 Provided geometrically identical shields are compared, this test method is also suitable for evaluation and grading of magnetic shielding materials.


attenuation ratio; Helmholtz coil; magnetic shield; pick-up coil; shielding factor;; ICS Number Code 17.220.20 (Measurement of electrical and magnetic quantities)

To find similar documents by ASTM Volume:

03.04 (Magnetic Properties)

To find similar documents by classification:

17.220.20 (Measurement of electrical and magnetic quantities Including measuring instruments, instrument transformers Electric energy meters in buildings, see 91.140.50)

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Publication Date

May 1, 2015

Document Type

Test Method

Page Count

5 pages

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