1. Rationale
This standard currently mandates that constant irradiance by maintained by controlling and monitoring the voltage supply to the furnace. Specifically, Section 7.1.2 says that an autotransformer or alternative control device can be used, but does not elaborate. Later in that section, it specifies that a transformer must be used to maintain the prescribed irradiance level if line voltage fluctuations exceed 2.5 (units missing). Modern smoke chambers use electronic temperature controllers which maintain a constant furnace temperature my varying the voltage to the furnace based on feedback from a furnace thermocouple. This ballot revises Section 7.1.2 to describe such a control system as an option, leaving the older transformer system in place as another option. Fig.2 would also be revised to show the optional furnace thermocouple (required if using a temperature controller). It also adds the missing units in the last sentence of the existing paragraph.
Keywords
fire; fire-test response standard; smoke; smoke chamber; smoke density; smoke obscuration; solids; specific optical density ;
Citing ASTM Standards
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