(Refer to the detailed answer for 6a68b2de3478942caa0b55d9.)

• Cargo holds are large, unoccupied/low-occupancy spaces with dusty and possibly flammable atmospheres, needing aspiration (smoke sampling) across a large volume; machinery spaces are occupied, hot, oily, with localised sources and need fast local heat/smoke detection.
• False alarms: machinery spaces have heat/smoke from normal engine operation, so heat/flame detectors are preferred there to avoid false alarms; cargo holds need smoke sampling to detect a fire hidden in the cargo.
• Response: cargo hold detectors give early warning of a fire in the cargo; machinery space detectors need to respond fast to protect occupied spaces.
• The hold system is monitored/aspirated from the bridge; machinery space detectors are distributed through the space.

• For the cargo hold smoke sampling system: test the aspirator/flow per sampling line, inject test smoke at a sample point and confirm the correct zone alarm; test the audible/visual alarms and panel indication; inspect the pipes for damage/blockage; carry out quarterly/annual servicing per the manufacturer.
• For machinery space detectors: apply heat/smoke to each point detector and confirm the correct zone; check the panel indication, the alarm, and the power supply (normal/emergency); test and record.
• All tests are recorded in the log.