On–off (two-position) controllers are normally applied to which kind of industrial variable/process duty where cycling around a setpoint is acceptable?

Introduction / Context:
On–off (two-position) control is the simplest feedback mode: the final element is either fully ON or fully OFF. It inherently produces cycling (limit cycles) around the setpoint. Understanding where this is acceptable helps in selecting the right controller for the job.

Given Data / Assumptions:

• We need a process tolerant of cycling and actuator chatter.
• Deadband or differential is usually provided to limit frequent switching.
• No fine setpoint tracking or linearity is required.

Concept / Approach:
Temperature control of thermal masses (ovens, incubators, water baths, domestic HVAC) is the classic on–off application because thermal inertia smooths the cycling and exact continuous modulation is unnecessary. By contrast, flow, fast pressure, or servo position systems benefit from proportional/PI/PID control with continuous output modulation.

Step-by-Step Solution:
Identify processes with natural damping (thermal capacitance).Assess tolerance to limit cycles; temperature systems typically tolerate small oscillations.Choose temperature duty as the appropriate application.

Verification / Alternative check:
Textbook examples and commercial thermostats illustrate two-position control for temperature. Industrial flow and servo applications rarely use on–off except for interlocks.

Why Other Options Are Wrong:
Flow/pressure/servo/composition: Usually require continuous control (PI/PID) for stability and accuracy.

Common Pitfalls:
Using on–off where actuator wear or process quality cannot tolerate cycling; lacking differential (hysteresis) can cause rapid chattering.

Final Answer:
Low-inertia temperature control (e.g., ovens, baths)