ISO 18237:2017 specifies:
- test equipment, test circuit and a procedure for the evaluation of the water separation capabilities of a dehydrator;
- a procedure for preparing test fluid;
- a procedure for obtaining and analysing the test fluid samples.
ISO 18237:2017 applies only to those dehydration units that can dry a hydraulic fluid to less than 20 % of the hydraulic fluid's water saturation level at the test temperature.
ISO 18237:2017 provides a test procedure that yields reproducible results for dehydrator water removal performance so that the performance of candidate units is compared on the same basis using the same test fluid.
This procedure can be used to test the dehydrator's capabilities on different types of hydraulic fluids at different conditions. Parts of the procedure might need to be changed to suit the hydraulic fluid's characteristics. For example, the testing of hydraulic fluids with high water solubility (many synthetic and fire-resistant fluids) needs higher concentrations of water at the start of the test; the testing of hydraulic fluids with zinc-based additives needs modifications to the Karl Fischer analysis procedure. However, comparison of performance can be made under the conditions defined in ISO 18237:2017.