🔍 Key Concepts

• Identify what type of field device figure E is (for example: flow, level, pressure, temperature, or limit switch). • Review common ISA-style symbols for flow switches and how they differ from pressure or level switches. • Compare the mechanical action of the paddle in figure E with the actuator shapes in the schematic symbols (circle, triangle, angle, etc.).

💭 Think About

• What physical quantity must move or change to operate the device shown in figure E? • Which symbol shape at the bottom best represents motion caused by fluid flow in a pipe, rather than motion from pressure on a diaphragm or temperature change in a bulb? • Does the device in figure E look like it is mounted directly in a pipeline with a paddle in the flow? Which symbol suggests that same kind of in-line flow actuation?

✅ Before You Answer

• Confirm that figure E is mounted in a pipe and uses a paddle or vane moved by the fluid. • Look for the symbol option that is explicitly used for a flow-actuated switch rather than a generic limit switch or pressure switch. • Make sure the chosen symbol shows a switch contact plus an additional mark that distinguishes it as being operated by flow, not by a mechanical lever or diaphragm.