Which of the following is an interlock safety example related to oil?

• A. Oil level is low
• B. Oil viscosity increases
• C. Oil color is brown
• D. Oil pressure is at a safe range

Answer: (D)

Interlocks prevent equipment from starting or continuing to run when conditions aren’t safe, and they rely on critical process variables to decide whether it’s okay to operate. For a lubricated system, oil pressure is a key safety-critical parameter: if the pressure is within the safe range, the interlock allows operation because proper lubrication is ensured. If pressure were too low (or too high), the interlock would trip to stop the machine and protect components from damage. So saying the oil pressure is in a safe range aligns with the way interlocks control safety, enabling operation only when lubrication is adequate. The other statements describe conditions or indicators that might prompt maintenance or alarms but don’t specify the enabling condition that the interlock uses to permit operation.