For testing refractoriness under load (RUL) of a refractory brick, the standard test specimen is heated in which type of furnace arrangement?

Introduction / Context:
Refractoriness under load (RUL) measures the temperature at which a refractory deforms under a specified compressive load. The test simulates high-temperature service conditions in industrial furnaces and kilns, where bricks must carry structural loads while resisting softening and creep.

Given Data / Assumptions:

• A shaped refractory specimen is loaded axially.
• Temperature is raised through a controlled heating profile until a defined deformation criterion is reached.
• A standardized furnace setup is required to provide stable, uniform heating to high temperatures.

Concept / Approach:
RUL testing commonly employs a carbon resistance furnace (or comparable electric furnace) with high-temperature capability and fine control, allowing accurate correlation between applied load and deformation temperature. The electrical resistance heating ensures uniform heating rates and minimal contamination of the specimen compared to combustion-type atmospheres.

Step-by-Step Solution:
Identify the test objective: measure deformation temperature under load.Select a furnace that provides precise high-temperature control: carbon resistance furnace.Confirm that alternatives (reducing/negative-pressure atmospheres) are not standard requirements for the RUL method.

Verification / Alternative check:
Standards for RUL testing (various national methods) specify electric resistance heating systems capable of stable high-temperature operation and accurate temperature measurement at the specimen position.

Why Other Options Are Wrong:
Neutral/reducing atmospheres: Atmosphere control may be used for specific materials but is not the defining feature.Negative pressure: Not a standard descriptor of the RUL test furnace.

Common Pitfalls:

• Assuming the atmosphere, rather than the heating method, defines the RUL apparatus.
• Confusing RUL with refractoriness (PCE) tests that use different criteria.

Final Answer:
carbon resistance furnace.