🔍 Key Concepts
• Figure C shows a pressure‑actuated switch with a sensing line and scale; relate this to the standard symbol for a pressure switch.
• Look at how the moving contact is drawn in each symbol option (1, 3, 6, 9) to decide if the switch is normally open or normally closed in its resting state.
• Note the small added shape (circle, triangle, or stepped line) near the contact in the symbols; this indicates what physical quantity (pressure, temperature, flow, etc.) operates the switch.
💭 Think About
• First, identify what kind of process variable operates the device in figure C: is it pressure, temperature, level, or flow? How can you tell from the coiled tubing and the gauge‑like scale?
• Compare the actuation shape in symbols 1, 3, 6, and 9. Which one uses the same type of indicator that standards typically use for a pressure‑sensing device?
• Decide whether the switch in figure C would change state (open/close) when pressure rises above a setpoint. Which of the candidate symbols shows that same normal (rest) contact position?
✅ Before You Answer
• Be sure you are matching pressure‑actuated vs. temperature/flow‑actuated symbols, not just any limit switch symbol.
• Verify which candidate symbol clearly uses a circle vs. triangle vs. stepped line as the sensing element indicator and recall which shape corresponds to pressure in common industrial diagrams.
• Confirm that the symbol you pick shows the correct normal contact state (open or closed) that most pressure switches would have when the sensed pressure is at zero or below the setpoint.