We use ASTM D-664 and are getting results that does not complie with the recommended method ASTM D-974 for Phosphate Ester hydraulic fluid (Skydrol/Hyjet type 4 fluid).

Does anyone have any experience with using D664 on theese fluids?

Edit Des 05:
Found out that ASATM D-974 will give the correct result (but it is possible to modify the 664 method to a higher pH).

This message has been edited. Last edited by: mr. Hughes,