🔍 Key Concepts

• Locate how lubricating oil is routed to and from the compressor (component A) in this refrigeration diagram. • Understand that an oil failure switch must sense oil pressure (often oil pump discharge) and usually compare it to crankcase or suction pressure. • Distinguish between controls on the refrigerant lines (suction/discharge) and controls on the oil system.

💭 Think About

• Trace the small lines leading to components W, X, Y, and Z and ask: which one is actually tied into the oil system of compressor A, rather than the cooling water or refrigerant lines? • For each labeled device, consider what variable it is likely sensing: cooling water flow/pressure, refrigerant suction/discharge pressure, or lubricating oil pressure. • Ask which device would need to shut the compressor down if oil pressure drops, and therefore must be positioned so it can "see" that pressure loss.

✅ Before You Answer

• Verify which of W, X, Y, Z is connected to the cooling water line only; that one cannot be the oil failure switch. • Verify which device is connected to both the compressor crankcase area and an apparent oil discharge or intermediate pressure line—that is your best candidate for an oil failure control. • Confirm that the remaining devices are located on the main refrigerant suction or discharge lines, making them more likely to be low-/high-pressure controls rather than an oil failure switch.