🔍 Key Concepts

• Relationship between float position, liquid level, and valve movement • How on-off (two position) control differs from proportional or floating control • Meaning of differential gap (deadband) in control systems

💭 Think About

• Look at what happens to the valve or piston when the level rises slightly above or below the set point: does the device drive fully one way, or does it move gradually? • Does the float position cause continuous proportional motion of the master piston, or does the system "wait" until the level has changed by a certain distance (X to X₀) before switching state? • Ask yourself whether this diagram shows any mechanism for accumulating reset (integral) action, or predicting rate of change (derivative) action, or if it is simply switching between two conditions.

✅ Before You Answer

• Identify whether the output element (pilot/master piston and valve) has only two stable positions or a continuously variable position over a range. • Determine the role of the distance marked X and X₀ on the right side: is this indicating a deadband/differential gap or a proportional band? • Confirm whether there is any visible arrangement (such as a motor-driven actuator) that would allow floating or throttling motion, versus a snap action between open/closed.