3.1 Freezing and thawing
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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 - 3.1 Freezing and thawing

3.1 Freezing and thawing

  3.1.1 Before and after temperature conditioning in accordance with paragraph 3.1.2 below, 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 paragraph 3.1.2.2.1 below;

    • .2 polyethylene tube, approximately 10 mm diameter, 400 mm long and sealed and weighted at one end, with suitable spacers attached. Figure 1 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 10ºC below the freezing point of the sample measured in accordance with standard 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 avoid flotation, and the spacers ensuring it remains approximately on the central axis of the cylinder. Place the cylinder with the sample in the chest, cool it 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 of 20 to 25ºC;

    • .2 repeat the procedure described in the above subparagraph three times to give four cycles of freezing and thawing; and

    • .3 condition the sample for seven days at 60ºC followed by one day at room temperature. The sample shall then be examined for visual signs of stratification, non-homogeneity or sedimentation.

Parent topic: 3 Tests for Type Approval of Foam Concentrates
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