1.1.1 The assessment and determination of surface
contamination (by salts) prior to application of
protective coatings is critical to their service life
expectancy. Determination of the level of surface
cleanliness is conducted by extraction of soluble salt
contaminants following ISO 8502-62--The Bresle
method, part of ISO 8502-9. The determination of the
level of salt is performed by following ISO 8502-9--
Field method for the conductometric determination of
water-soluble salts. The field execution of this
requirement involves using a syringe to inject deionized
water into the Bresle patch, washing the
substrate surface inside the patch, then extracting the
test water for direct measurement of conductivity.
Details of this procedure are provided in Appendix A
(mandatory). Once a conductive value is determined by
the conductivity meter, expressed as micro Siemens
per centimeter. ISO 8502-9 provides a
procedure to calculate the equivalent weight of the
surface concentration as total surface density of the
salts.
1.1.2 Step-by-step execution of the ISO 8502-6 and
8502-9 test requirements introduces a number of
potential variances during the field evaluation. Some
examples include the sensitivity and resolution of the
conductivity meter, cycle time of the test water inside
the Bresle patch, human errors in measuring and
injecting the test water, and general operator
experience. It is known that the accumulation of these
individual process variances can add up to create an
overall variance in the ISO protocol.
1.1.3 The range of variance in ISO 8502-6 and 8502-9
has been demonstrated by extensive laboratory tests
conducted by a member of this task group.3 The
precision of a single ISO 8502-9 test result was
determined to be ±8.2 mg/m2 in the range 30 to 80
mg/m2. The absolute variance, and not the relative or
percent variance, was found to be constant in this
range. See Appendix B (nonmandatory) for details
about these tests and the data analysis. The test
method defined in ISO 8502-9 allows certain execution
parameters of the test (e.g., size of adhesive patch,
volume of test solution, and time of dissolution of salts
inside the adhesive patch: the dwell time) to vary. This
standard adopted best practices and has set the
parameters in Appendix A. With a dwell time at a
minimum of 90 seconds, the variance from operator
error was found reduced dramatically in case the
operator timing is not perfect. Hence, a dwell time of 90
seconds was adopted in Appendix A. For the purpose
of defining equivalence, the procedure in Appendix A
shall be used to create the reference values to which
the candidate method will be validated. See Appendix
B for the test rationale.
1.1.4 Any equivalent tools, methods, or procedures
then must show that they meet the same criteria,
thereby providing the same weight measures, and be
within the same range of variance as would be
produced by following the procedure in ISO 8502-9.
1.1.5 The objective of this standard is to determine
whether methods other than the Bresle patch
application method are suitable alternatives for
measuring salt contamination in the field. Although
tests may be performed on flat, horizontal surfaces for
ease of use, each method should also be capable of
gathering measurements on vertical and overhead
surfaces. When such measurements cannot be made
on vertical or overhead surfaces, this limitation must be
noted in the validation report (Section 3).
| File Size : | 1
file
, 180 KB |
| ISBN(s) : | 1575902222 |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 11/07/2008 |
