CHEMCO Exit Exam • Set 13 Question 18 of 30

The atmosphere in a tank is too lean if it is

✓

Direct Answer

Option A: incapable of supporting combustion because the hydrocarbon content is below the LFL (LowerFlammable Limit)

According to ISGOTT, an atmosphere is considered "too lean" when the hydrocarbon gas concentration is below the Lower Flammable Limit (LFL). At this point, there isn't enough fuel (hydrocarbon) in the air-gas mixture to support combustion, making ignition impossible.

All Options

incapable of supporting combustion because the hydrocarbon content is below the LFL (LowerFlammable Limit) (Correct Answer)

capable of supporting combustion because the hydrocarbon content is above the UFL (UpperFlammable Limit)

capable of supporting a fire once started

not safe for ballasting

Detailed Explanation & Context

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Advanced Training for Chemical Tanker Cargo Operations (CHEMCO).

Practice Full CHEMCO Set 13

Test yourself with 30 interactive questions, live timer, and instant score.

Launch Practice Simulator →

Question Discussion & Notes

Have a doubt, memory trick, or exam update? Share your insights with fellow mariners.

Loading mariner discussions...

« Previous Question Next Question »

More Questions in CHEMCO Set 13

View All 30 →

Q1 Prior to entering a cargo pump room, you should ensure that Q2 The complete details of a crude oil washing system aboard your vessel, including the operating sequences and procedures, design characteristics, a description of the system, and required personnel will be found in the Q3 You are testing a tank that contained gasoline by using a combustible gas indicator. Under testing, the tank sample caused the needle to move rapidly to 100 on the dial then fall to zero. What is the concentration of flammable gas? Q4 Which of the following documents carried by a ship is not issued under the MARPOL convention? Q5 Which of the following conditions need NOT be satisfied while discharging oil or oil mixtures from ships into the sea? Q6 Which tanker discharge pattern would be the safest and most efficient? Q7 Ballast water exchange should be done: Q8 As per requirements of Marpol, Annex 1, all ships delivered on or after 1st Aug. 2010 with an aggregate oil fuel capacity 600 m3 and above, the oil fuel can be carried in Q9 The atmosphere in a tank is too rich when it is Q10 Reid vapor pressure is __________.