5.1 The purpose of a hydraulic fluid is to cool and lubricate fluid power components, as well as transmit power. This practice provides uniform guidelines for comparing fluids in terms of their power-transmitting abilities as reflected in their effect on hydraulic system or component efficiency. Standard test methods ISO 4409 and ISO 4392 provide specifications for evaluating the steady state performance of hydraulic pumps and motors but do not address technical requirements specific to hydraulic fluid testing.

5.2 Differences in fluid performance may be relatively small. Consequently, it is essential that the necessary experimental controls are implemented to ensure consistency in operating conditions and duty cycle when comparing the energy efficiency of different hydraulic fluid formulations.

5.3 Practical advantages of enhanced hydraulic system efficiency may include increased productivity (faster machine cycle time), reduced power consumption (electricity or fuel), and reduced environmental impact (lowered emissions).

5.4 This practice implies no evaluation of hydraulic fluid quality other than its effect on hydraulic system efficiency.

1.1 This practice covers all hydraulic fluids.

1.2 This practice is applicable to both laboratory and field evaluations.

1.3 This practice provides guidelines for conducting hydraulic fluid evaluations. It does not prescribe a specific efficiency test methodology.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.