8.4 Measurements and Observations on the Test Specimen

  8.4.1.1 All temperature measurements should be recorded at intervals not exceeding 1 min.

  8.4.1.2 When calculating temperature rise on the unexposed surface of the test specimen, this should be done on an individual thermocouple-by-thermocouple basis. The average temperature rise of the unexposed surface should be calculated as the average of the rises recorded by the individual thermocouples used to determine the average temperature.

  8.4.1.3 For "A" class divisions, excluding doors, the average temperature rise on the unexposed face of the specimen should be calculated from the thermocouples specified in 7.5.1.1 only.

  8.4.1.4 For "B" and "F" class divisions, excluding doors, the average temperature rise on the unexposed face of the specimen should be calculated from the thermocouples specified in 7.5.2.1 only.

  8.4.1.5 For "A", "B" and "F" class doors, the average temperature rise on the unexposed face of the specimen should be calculated from the thermocouples specified in 7.5.3.1 only. For a double-leaf door, all ten thermocouples used on both door leaves should be used for this calculation.

 The occurrence and duration of any flaming on the unexposed surface, together with the location of the flaming, should be recorded. In cases where it is difficult to identify whether or not there are flames then the cotton-wool pad should be applied to the area of such disputed flaming to establish whether ignition of the pad can be initiated.

  8.4.3.1 Tests with the cotton-wool pad are used to indicate whether cracks and openings in the test specimen are such that they could lead to the passage of hot gases sufficient to cause ignition of combustible materials.

  8.4.3.2 A cotton-wool pad is employed by placing the frame within which it is mounted against the surface of the test specimen, adjacent to the opening or flaming under examination, for a period of 30 s, or until ignition (defined as glowing or flaming) of the cotton-wool pad occurs (if this happens before the elapse of the 30 s period). Small adjustments in position may be made so as to achieve the maximum effect from the hot gases. A cotton-wool pad should be used only once.

 Where there are irregularities in the surface of the test specimen in the area of the opening, care should be taken to ensure that the legs of the support frame are placed so that clearance between the pad and any part of the test specimen surface is maintained during the measurements.

 The cotton-wool pad should be applied freely and not necessarily parallel to the surface of the specimen, and not always such that the crack or opening is central to the pad. The pad should be positioned in the flow of hot gases but should never be positioned such that any part of the pad is closer than approximately 25 mm from any point of the test specimen. For example, to adequately evaluate the hot gas leakage around a door it may be necessary to use the pad both parallel and normal to the face of the door or possibly at an oblique angle within the confines of the door frame.

 The operator may make 'screening tests' to evaluate the integrity of the test specimen. Such screening may involve selective short duration applications of the cotton pad to areas of potential failure and/or the movement of a single pad over and around such areas. Charring of the pad may provide an indication of imminent failure, but an unused pad should be employed in the prescribed manner for an integrity failure to be confirmed.

  8.4.4.1 Tests with the gap gauges are used to indicate whether cracks and openings in the test specimen are of such dimensions that they could lead to the passage of hot gases sufficient to cause ignition of combustible materials.

  8.4.4.2 The gap gauges should be used at intervals which will be determined by the apparent rate of the specimen deterioration. Two gap gauges should be employed, in turn, and without undue force to determine:

• whether the 6 mm gap gauge can be passed through the specimen such that the gauge projects into the furnace, and can be moved a distance of 150 mm along the gap, or
• whether the 25 mm gap gauge can be passed through the specimen such that the gauge projects into the surface.

 Any small interruption to the passage of the gauge that would have little or no effect upon the transmission of hot gases through the opening should not be taken into account, e.g. small fastening across a construction joint that has opened up due to distortion.

 The deflection of an "A", "B" or "F" class test specimen, and additionally in the case of a door the maximum displacement of each corner of the door leaf relative to the door frame, should be recorded during the test. These deflections and displacements should be measured with an accuracy of ± 2 mm.

 Observations should be made of the general behaviour of the specimen during the course of the test and notes concerning the phenomena such as cracking, melting or softening of the materials, spalling or charring, etc., of materials of construction of the test specimen should be made. If quantities of smoke are emitted from the unexposed face this should be noted in the report. However, the test is not designed to indicate the possible extent of hazard due to these factors.