🔍 Key Concepts

• Difference between normally closed (NC) and normally open (NO) contacts in schematic symbols • How a pressure-operated device is shown in symbols (diaphragm or bellows shape attached to the contact) • Distinguishing a basic switch symbol from one that is specifically pressure actuated

💭 Think About

• First, among the numbered symbols, which ones clearly show closed contacts when no force is applied? Eliminate any that show an air gap between contacts at rest. • Next, look only at those NC symbols and decide which one has the pressure-actuating element (often drawn like a diaphragm or bellows) rather than temperature, flow, or a plain mechanical operator. • Compare the special shapes under or beside the contacts: which shape most logically represents pressure on a diaphragm rather than a float, paddle, or thermal bulb?

✅ Before You Answer

• Verify that the symbol you pick shows the contacts touching in the normal (unactuated) position. • Confirm that the operator attached to the contacts is the one used for pressure, not temperature or flow—look for the diaphragm/bellows style shape. • Make sure you are not choosing a generic limit switch or pushbutton symbol; the question specifically requires a pressure switch, not just any NC switch.