Which control is intended to prevent an unsafe condition of temperature, pressure, or liquid level?

The safety limit control is designed specifically to prevent unsafe conditions related to temperature, pressure, or liquid levels. This control acts as a safeguard by monitoring these parameters and can shut down the equipment or initiate other safety mechanisms when predetermined thresholds are exceeded. Its primary function is to ensure that the system operates within safe parameters, thereby protecting both equipment and personnel from potential hazards.

While operating controls manage the normal operational conditions of a system, safety limit controls are critical for scenarios where those conditions may reach dangerous levels. Modulating controls adjust variables within a system to maintain desired operating conditions, but they do not provide a fail-safe mechanism against extreme situations. Emergency controls are typically the last line of defense, activated in critical situations, but the safety limit control is the proactive measure ensuring safety during standard operations.