3.1 Freezing and thawing
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.798 – Guidelines for Performance and Testing Criteria and Surveys of Medium-Expansion Concentrates for Fire-Extinguishing Systems – (Adopted on 9 June 1997) - Annex - Guidelines for Performance and Testing Criteria and Surveys of Medium-Expansion Foam Concentrates for Fire-Extinguishing Systems - 3 Tests for Type Approval of Foam Concentrates - 3.1 Freezing and thawing

3.1 Freezing and thawing

  3.1.1 Before and after temperature conditioning in accordance with 3.1.2, the foam concentrate should show no visual sign of stratification, non-homogeneity or sedimentation.

  3.1.2 Freezing and thawing test

  • .1 Apparatus:

    • .1 freezing chamber, capable of achieving temperatures required as stated in .2.1 below;

    • .2 polyethylene tube, approximately 10 mm diameter, 400 m long and sealed and weighted at one end, with suitable spacers attached (Figure 1 of MSC/Circ.582 shows a typical form); and

    • .3 500 ml cylinder approximately 400 mm high and 65 mm in diameter.

  • .2 Procedure:

    • .1 set the temperature of the freezing chamber to a temperature which is 10°C below the freezing point of the sample measured in accordance with BS 5117: Section 1.3 (excluding 5.2 in the standard);

      To prevent the glass measuring cylinder from breaking, due to expansion of the foam concentrate on freezing, insert the tube into the measuring cylinder, sealed end downward, weighted if necessary to void flotation, the spacers ensuring it remains approximately on the central axis of the cylinder.

      Place the sample in the cylinder in the chest, cool and maintain at the required temperature for 24 h. At the end of this period thaw the sample for not less than 24 h and not more than 96 h in an ambient temperature range of 20°C to 25°C.

    • .2 repeat .2.1 above three times to give four cycles of freezing and thawing;

    • .3 examine the sample for stratification and non-homogeneity; and

    • .4 condition the sample for 7 days at 60°C followed by one day at room temperature.

Parent topic: 3 Tests for Type Approval of Foam Concentrates
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