Which type of control is used for monitoring flame conditions in a furnace?

Flame roll-out control is specifically designed to monitor flame conditions within a furnace. This type of control is essential for ensuring safety during the combustion process. When the flame sensor detects that the flame is rolling out of the combustion chamber or not burning properly, it can trigger a shutdown of the furnace or engage safety measures to prevent hazardous situations.

This capability is crucial in maintaining safe operating conditions, as improper flame conditions can lead to dangerous situations, such as explosions or system failures. By continuously monitoring the flame, this control helps ensure that the combustion process remains stable and efficient.

The other types of controls mentioned, such as pressure control, bimetal control, and auxiliary limit control, serve different purposes. Pressure control is used for managing system pressure, bimetal control often regulates temperature using thermal expansion, and auxiliary limit control involves safeguards to prevent overheating or overcurrent situations. Thus, they do not focus specifically on monitoring the integrity of the flame within the furnace, which is the primary function of flame roll-out control.