At what maximum gas concentration must the...

At what maximum gas concentration must the...

Question 1 of 270705eccef9dbacbc34ba4d45d26

At what maximum gas concentration must the fixed gas detection system on a LNG ship activate an audible and visual alarm?

Question 1 of 27070

Q

At what maximum gas concentration must the fixed gas detection system on a LNG ship activate an audible and visual alarm?

🔍 Key Concepts

• Lower Flammable Limit (LFL) – what it represents for a flammable gas like LNG vapor • Difference between % by volume and % of LFL in gas detection alarm settings • Purpose of a fixed gas detection system alarm – early warning vs. imminent danger threshold

💭 Think About

• Ask yourself: do international gas ship standards usually set alarms in terms of an absolute gas percentage in air, or as a percentage of the LFL? • Think about safety margins: should the alarm go off when gas is already near the flammable range, or well before it? How does that influence whether the number is higher or lower? • Consider why using % of LFL is safer and more universal than using plain % by volume for different gases with different flammable limits.

✅ Before You Answer

• Verify whether cargo area gas detectors on gas carriers are normally calibrated and specified in % of LFL, not % by volume • Check which of the options mention lower flammable limit (LFL) explicitly and focus on those first • Confirm that the chosen percentage represents an early warning level (not an emergency shutdown level) relative to the LFL