Pneumatics/Hydraulics for Processing Elements (Control Elements) lists which items?

• A. Directional Control Valves, Isolating Valves, and Pressure Valves
• B. Switches
• C. Actuators
• D. Valves only

Answer: (A)

Processing elements in pneumatics and hydraulics are the parts that regulate and route fluid power, not the parts that sense or the parts that move the load. The items that fit this role are valves: directional control valves steer the fluid to the correct actuator paths, isolating valves allow safe on/off isolation of sections of the circuit, and pressure valves (like relief or sequence valves) manage and limit system pressure. Switches are sensors, and actuators are the devices that convert fluid power into motion, so they’re not part of the processing/control element group. Saying “valves only” misses the need for isolating and pressure-control valves, which is why the best choice is the one that includes all three kinds of valves.