🔍 Key Concepts
• Figure D shows a sensing bulb with a capillary tube going to a switch housing – this is a temperature-actuated switch/thermostat.
• In the symbol list, look for a switch contact that is operated by a temperature-sensing element, usually shown by a special shape on or near the contact.
• Distinguish between symbols for pressure (often circles), flow (paddles/lines), and temperature (often angular or bulb‑style marks).
💭 Think About
• First, decide what physical quantity the device in figure D is sensing and controlling. Is it pressure, flow, level, or temperature?
• Then, scan the symbols and separate out which ones are plain mechanical limit switches, which are pressure-operated, and which are thermostatic or temperature-operated.
• Compare the unique graphic attached to each switch symbol (triangle, circle, bulb/loop, etc.). Which one best matches a temperature bulb and capillary like you see in figure D?
✅ Before You Answer
• Verify that the chosen symbol clearly shows a switch contact (two terminals with a movable arm).
• Confirm that the added mark next to the contact corresponds to temperature rather than pressure or flow (do not pick symbols with circles that usually indicate pressure).
• Make sure you are not picking a simple hand‑operated limit switch; the device in figure D must show some form of remote sensing element in its symbol.