ISO 6072:2011

Overview

ISO 6072:2011, "Rubber - Compatibility between hydraulic fluids and standard elastomeric materials," specifies standardized test methods to evaluate how hydraulic fluids affect representative elastomer compositions. The standard defines formulations, mixing and vulcanization procedures for five standard test elastomers (NBR 1, NBR 2, FKM 2, EPDM 1, HNBR 1) and sets out controlled immersion tests to measure changes in physical properties. It is intended for baseline comparisons of hydraulic fluids - including mineral-based, fire‑resistant and biodegradable hydraulic fluids - against these elastomer types.

Key topics and requirements

• Standard test elastomers: Provides compositions and manufacturing procedures for:
  • Acrylonitrile‑butadiene rubbers (NBR 1 and NBR 2)
  • Fluorocarbon rubber (FKM 2)
  • Ethylene‑propylene‑diene rubber (EPDM 1)
  • Hydrogenated NBR (HNBR 1)
• Test measurements: Evaluates changes in:
  • Volume (swelling or shrinkage)
  • Hardness
  • Tensile strength
  • Elongation at break
• Elastomer Compatibility Index (ECI): A one‑line designation summarizing the change in key properties for a fluid/elastomer pair under specified test conditions. The ECI enables quick, standardized comparison between fluids.
• Procedures and controls: Specifies mixing, vulcanization and control tests (e.g., hardness, tensile, density) and references related test methods such as ISO 37, ISO 48, ISO 1817 and ISO 2393.
• Scope limitations: Does not supply service-grade elastomer formulations for end-use, though service elastomers can be tested using ISO 6072 procedures.

Practical applications

• Hydraulic system design and maintenance: Select compatible fluid and seal materials to reduce seal failure, leakage and downtime.
• Fluid formulation and additive development: Fluid and additive manufacturers can benchmark new fluids against standard elastomers to improve compatibility.
• Quality assurance and procurement: Oil suppliers can quote an ECI to help OEMs and maintenance teams assess suitability without extensive in-house screening.
• Materials testing laboratories: Provides reproducible methods for producing standard test rubbers and reporting test results.

Who uses this standard

• Hydraulic system engineers and designers
• Seal and elastomer manufacturers
• Lubricant and hydraulic fluid formulators
• Testing and certification laboratories
• Maintenance and reliability teams in industrial, mobile and aerospace sectors

Related standards

• ISO 37 (tensile properties), ISO 48 (hardness), ISO 1817 (effect of liquids), ISO 2393 (rubber mixing/vulcanization), ISO 2781 (density), ISO 5598 (vocabulary), ISO 6743‑4 (hydraulic lubricants).

Keywords: ISO 6072:2011, hydraulic fluids, elastomer compatibility, ECI, NBR, FKM, EPDM, HNBR, compatibility testing, hydraulic seals.