Overview
EN ISO 4404-2:2010 - Petroleum and related products - Determination of the corrosion resistance of fire-resistant hydraulic fluids - Part 2: Non-aqueous fluids (ISO 4404-2:2010) specifies a standardized laboratory procedure to evaluate the corrosion-inhibiting properties of non-aqueous, fire‑resistant hydraulic fluids (category HFD as classified in ISO 6743‑4). The method gives a qualitative and quantitative assessment of metal corrosion when exposed to HFD fluids under controlled conditions, supporting product development, quality control and compliance activities.
Key topics and requirements
- Scope: Test applies to non‑aqueous fire‑resistant hydraulic fluids (HFD); aqueous fluids are covered in ISO 4404‑1.
- Test principle: Polished metal test pieces are immersed in test fluid at (35 ± 1) °C for (672 ± 2) h; appearance and mass change are assessed.
- Metal test pieces: Standard set includes steel, copper, brass, zinc and aluminium (composition ranges given in the standard); other metals/alloys may be substituted for specific installations.
- Specimen dimensions & preparation: Rectangular strips 100 × 20 mm, thickness 1–2 mm; polished using silicon carbide abrasive (125, 65, 37, 26 μm - equivalent to P120–P600); cleaned with heptane and handled only with forceps post‑preparation.
- Apparatus & reagents: Borosilicate beakers (400 ml), glass hooks and watch‑glasses, nylon spacers/bolts, thermostatically controlled bath or oven with uniform temperature, analytical balance (0,2 mg resolution), heptane and toluene.
- Sample size & layout: Minimum laboratory sample 3 L; typically 10 beakers (nine containing test pieces, one blank) with ~250 ml fluid each; single and paired metal exposures are used.
- Evaluation & reporting:
- Corrosion classified on an appearance scale (0–5) for liquid and vapour zones.
- Test fluid condition classified (0–5).
- Mass change reported to the nearest 0.5 mg.
- Test report must reference ISO 4404‑2:2010, product ID, results, deviations and test date.
- Safety note: The procedure may involve hazardous materials; users must follow appropriate safety practices.
Applications and users
- Hydraulic fluid manufacturers - product development and certification for corrosion resistance.
- Independent testing laboratories - standardized test method for comparative testing and QC.
- End‑users / OEMs / plant engineers - specification and selection of HFD fluids for hydraulic systems, material compatibility checks.
- Procurement and compliance teams - validation against industry standards and supplier claims.
Related standards
- ISO 6743‑4 - classification of hydraulic fluids (family H).
- ISO 4404‑1 - corrosion tests for aqueous hydraulic fluids (HFA, HFB, HFC).
- Supporting references: ISO 3170 (sampling), ISO 3819 (beakers), ISO 5272 (toluene specification).
Keywords: EN ISO 4404-2:2010, corrosion resistance, fire-resistant hydraulic fluids, non-aqueous fluids, HFD, hydraulic systems, test procedure, metal corrosion testing.