🔍 Key Concepts

• Review how normally open (NO) and normally closed (NC) contacts are drawn in simple limit-switch symbols (contacts touching vs. separated). • Compare the extra graphic elements (circle, triangle, semicircle) that indicate what sensing element operates the switch: pressure bellows, temperature bulb, float, or flow paddle. • Relate device F in the upper right (mechanical float level switch) to the matching schematic symbol in the bottom row that uses the float shape.

💭 Think About

• First, identify in the bottom symbols which ones are clearly NO vs. NC without any special sensing element. Use those to decide which side means open or closed. • Next, look only at the symbols that incorporate a circle (float) and decide which of those shows the contacts in the open position, as drawn at rest. • Ask yourself: if the liquid level is low and the float is hanging down, would that switch’s contacts be open or closed according to the symbol?

✅ Before You Answer

• Confirm which symbol style in this figure represents NO (contacts not touching) before considering the special shapes. • From the symbols that include a circle representing the float, determine which one shows the contacts in the same NO orientation as the plain NO contact symbol. • Verify that you are not confusing symbols that use triangles or semicircles (often pressure, flow, or temperature elements) with the one that specifically indicates a float level element.