A dummy specimen should remain mounted in the position normally
occupied by a specimen whenever the equipment is in stand-by operation.
This is a necessary condition of the continuous monitoring procedure
which is accomplished by measuring:
-
.1 the millivolt signals from both the stack thermocouples
and the total radiation pyrometer mounted securely on the specimen
holder frame facing the surface of the radiant panel; or
-
.2 the millivolt signals from both the stack thermocouples
and a heat-fluxmeter positioned at 350 mm from the exposed hot end
of a marine board specimen of about 20 mm thickness (see appendix, paragraph 4.3.2).
Either of these measurement methods would be satisfactory
for determining that an appropriate thermal operating level has been
achieved. The use of the radiation pyrometer is preferable since it
permits continuous monitoring of panel operating level even when tests
are in progress. Both signals should remain essentially constant for
three minutes prior to the test. The observed operating level of either
the radiation pyrometer or the fluxmeter should correspond, within
2%, to the similar required level specified in Table 1 and referred to in the calibration
procedure mentioned in 6.1 above.