SAE AS9968A

This document describes a standard method for measuring the viscosity of thickened (AMS1428) Type II/III/IV Aircraft Deicing/Anti-icing Fluids. The determination of viscosity for a Non-Newtonian fluid is very sensitive to shear and differences in sample chamber geometry. Even slight differences can have a large effect on measurement results. The test parameters and associated error for this standard are applicable to the Brookfield LV viscometer. A Brookfield LV or equivalent viscometer shall be used. To be considered equivalent, an alternate viscometer must demonstrate statistically equivalent performance, i.e., accuracy and precision when testing thickened (AMS1428) fluids using the same test parameters and conditions.Test parameters and conditions outside of the ranges described within this standard may be used only if they meet minimum limits for precision and accuracy established for the Brookfield LV viscometer. To compare viscosities, the same test parameters and conditions (including spindle number, rotation speed, sample volume and container type, sample temperature, and measurement duration) shall be used. The scope of the standard has been expanded to allow other important uses aside from field verification and auditing purposes. A number of editorial and organizational revisions were also made. The expanded scope allows the standard to be used for AMS1428 conformance testing or for quality assurance purposes when measurement of viscosity using different spindles, or temperatures different from 20 °C or rotational speeds different from 0.3 rpm is required. At the same time the standard preserves the original methodology used for field verification and auditing purposes. New guidelines for reporting viscosity results make clearer that the results of independent measurements can only be compared when the same test parameters and conditions have been used. The word “Brookfield” has been removed from the title because alternate viscometers (different from the Brookfied LV model) will be allowed if the alternative viscometer demonstrates equivalent performance to the Brookfield LV. Section 3 was updated to include a significant amount of new content which has been divided into four new sections entitled: Summary of Test Method, Equipment and Test Parameters, Calibration of Test Equipment, and Testing of Samples. The contents of Sections 4 and 5 were revised and combined into a new section entitled Reporting. An appendix was added to provide addtional information and explanation of test parameters and conditions which have an effect on accuracy and precision of viscosity measurements.