ISO 20783-1:2011

Overview

ISO 20783-1:2011 specifies a laboratory test method to assess emulsion stability of fire‑resistant hydraulic fluids in category HFAE (as defined in ISO 6743-4). The standard covers preparation of a representative emulsion using defined test waters, controlled ageing of the emulsion in Hirschsohn flasks, and visual assessment of separation phenomena (oil separation and creaming). This part applies only to HFAE fluids and is not applicable to HFAS fluids.

Key topics and requirements

• Scope and applicability: Test method for HFAE-type fire‑resistant fluids; excludes HFAS.
• Sample preparation: Prepare 1 L of emulsion using the manufacturer’s recommended oil concentration and one of the four standard test waters given in Annex A (waters with defined salt concentrations).
• Reagents and apparatus: Demineralized and potable water, acetone or isopropyl alcohol, dishwasher detergent; Hirschsohn flasks (150 ml or 200 ml), cork bungs, and an oven capable of (70 ± 2) °C or (50 ± 2) °C.
• Test conditions: Two options by agreement:
  • 70 ± 2 °C for 1 week, or
  • 50 ± 2 °C for 3 weeks.
• Procedure: Place three flasks filled to the mid‑scale with emulsion into the oven; observe while still hot at test end.
• Assessment categories:
  • Oil separation (A): 1A (no oil) - 3A (continuous film).
  • Creaming (R): 1R (no creaming) - 3R (>1 ml).
• Expression of results: Report the category for which at least two flasks agree (e.g., “1A - 2R”); if all three differ, repeat the test and follow specified reporting rules.
• Annex A: Provides recipes for four standard test waters (composition and preparation notes, including CaSO4·2H2O handling).
• Test report: Must include reference to ISO 20783‑1:2011, product ID, water type and oil percentage, test conditions, stability result, water separation, deviations and date.
• Precision: Not formally determined; limited interlaboratory guidance available.

Applications and users

ISO 20783-1:2011 is used for:

• Quality control and acceptance testing of fire‑resistant HFAE hydraulic fluids
• Product development and compatibility verification with specified water types
• Independent testing laboratories and OEMs specifying fluid performance
• Procurement and specification writers who require documented emulsion stability data

This test helps manufacturers, testing labs, and purchasers evaluate emulsion stability, mitigate operational risks and ensure reliable performance of fire‑resistant hydraulic fluids.

Related standards

• ISO 6743-4 (classification for family H fluids)
• ISO 20783-2 (Part 2: fluids in category HFB)
• ISO 3170 (manual sampling of petroleum liquids)
• ISO 3696 (water for analytical laboratory use)

Keywords: ISO 20783-1:2011, emulsion stability, HFAE, fire-resistant fluids, oil separation, creaming, test waters, Hirschsohn flasks, test method.