🔍 Key Concepts

• Fixed (permanently connected) fire-extinguishing systems required on large diesel / crosshead engines • Differences between crankcase explosion protection (relief valves, oil mist detectors) and fire extinguishing systems • Protection of scavenging spaces versus exhaust manifolds or turbocharger piping

💭 Think About

• Which part of a large crosshead engine most commonly accumulates unburned oil vapors and deposits that can ignite and spread rapidly? • For crankcases over a certain volume, what type of safety features are usually required—are they fire extinguishing systems, or something else? • Among the options given, which area is typically enclosed and difficult to access quickly with portable extinguishers, making a permanently connected system more important?

✅ Before You Answer

• Distinguish between explosion relief / detection devices and fire extinguishing devices in regulations. • Check which space is frequently mentioned in SOLAS/46 CFR/IMO guidance as needing a fixed fire extinguishing system on large diesel or crosshead engines. • Verify which options involve an enclosed space directly connected to the cylinders where scavenge fires are a known hazard.