3.6 Film formation of the foam solution (if applicable)
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1312 – Revised Guidelines for the Performance and Testing Criteria, and Surveys of Foam Concentrates for Fixed Fire-Extinguishing Systems – (10 June 2009) - Annex – Revised Guidelines for the Performance and Testing Criteria, and Surveys of Foam Concentrates for Fixed Fire-Extinguishing Systems - 3 Tests for Type Approval of Foam Concentrates - 3.6 Film formation of the foam solution (if applicable)

3.6 Film formation of the foam solution (if applicable)

  3.6.1 The spreading coefficient should be determined using the following formula:

S = Tc -Ts -Ti

where:

  • S is the spreading coefficient;
  • Tc is the surface tension of cyclohexane (N/m);
  • Ts is the surface tension of the foam solution (N/m);
  • TI is the interfacial tension between the foam solution and cyclohexane (N/m).
  • Tc, Ts and Ti should be determined according to paragraph 3.6.2 below.
  • The spreading coefficient S should be greater than 0.

  3.6.2 Determination of Tc, Ts and Ti

  • .1 materials:

    • .1 solution of foam concentrate, at the recommended usage concentration in distilled water complying with standard ISO 3696; and

    • Note: The solution may be made up in a 100 ml volumetric flask using a pipette to measure the foam concentrate.

    • .2 for Tc and Ti , cyclohexane of purity not less than 99%;

  • .2 procedures for surface tension: determine Ts at a temperature of 20 ± 2ºC using the ring or plate method of standard ISO 304; and

  • .3 procedure for interfacial tension: after measuring the surface tension in accordance with subparagraph .2 above, introduce a layer of cyclohexane at 20 ± 2ºC onto the foam solution, being careful to avoid contact between the ring or plate and the cyclohexane. Wait 6 ± 1 min and measure Ti .

Parent topic: 3 Tests for Type Approval of Foam Concentrates
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