6.2 Daily verification

 As a means of assuring continued proper adjustment of the apparatus, the following tests should be performed on a daily basis, or more frequently if the nature of the specimens makes this necessary.

  6.2.1 Adjustment of the Pilot Burner, the acetylene and air supply should be adjusted to provide a flame length of about 230 mm^footnote. When this has been done, the flame length as viewed in a darkened laboratory will be seen to extend about 40 mm above the upper retaining flange of the specimen holder. The burner spacing from the specimen is adjusted while the radiant source is operating by the use of softwood splines of 3 mm thickness and of 10 mm and 12 mm width. When these splines are moved during a two second exposure along the flame length, between the pilot burner flame and a dummy specimen surface, the 10 mm spline should not be charred but the 12 mm spline should show char. With the specimen in the vertical position, the charring of the 12 mm spline should occur over a vertical distance of at least 40 mm from the upper exposed edge of the specimen (see Figure 9).

  6.2.2 The stack gas thermocouples should be cleaned by light brushing at least daily. This cleaning may be required even more frequently, in some instances before each test, when materials producing heavy soot clouds are tested. These thermocouples should also be individually checked for electrical continuity to ensure the existence of a useful thermojunction. Following daily cleaning of the parallel connected stack gas thermocouples, both they and the compensating junction should be checked to verify that the resistance between them and the stack is in excess of 10⁶ ohms.