Tank Atmosphere Control Flashcards
7 cards from real Tanker Familiarization practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Tank Atmosphere Control flashcards as text
What is the 'flammable range' of a hydrocarbon-air mixture?
Answer: The concentration range between LEL and UEL where ignition and explosion can occur
The flammable range encompasses all vapor concentrations between the LEL and UEL where an ignition source could cause a fire or explosion.
When using a catalytic-type combustible gas indicator (explosimeter), why must it NOT be used in an oxygen-deficient atmosphere?
Answer: It requires oxygen for its catalytic sensor to function and will give inaccurate low readings
Catalytic sensor explosimeters require sufficient oxygen to oxidize the hydrocarbon sample; in low-oxygen atmospheres the reading will be falsely low, creating a dangerous false sense of security.
What is the significance of 'flash point' in cargo tank atmosphere control?
Answer: The minimum temperature at which a liquid cargo produces enough vapor to form an ignitable mixture
Flash point determines at what cargo temperature sufficient vapor is produced to create a flammable atmosphere, directly affecting tank atmosphere risk assessment.
A tanker officer notices the IG system oxygen analyzer is reading 9.5% during inerting. What is the correct immediate action?
Answer: Stop inerting operations immediately and investigate the cause
Any oxygen reading above 8% in the IG supply requires immediate cessation of inerting operations to prevent introducing a potentially flammable atmosphere into cargo tanks.
What is the risk of 'breathing' in a cargo tank not connected to an active inert gas supply?
Answer: The tank may lose positive pressure and air may enter, raising oxygen levels
Temperature and pressure fluctuations cause tanks to 'breathe'—when pressure drops, air can be drawn in through vents, increasing oxygen content and potentially creating a flammable atmosphere.
Which regulation requires chemical tankers carrying flammable cargoes to have an inert gas system or equivalent?
Answer: IBC Code Chapter 8
The IBC Code (International Bulk Chemical Code) Chapter 8 specifies cargo tank atmosphere control requirements including inerting for flammable liquid cargoes.
What is 'nitrogen blanketing' used for in specialized tanker operations?
Answer: To maintain an inert nitrogen atmosphere over sensitive cargoes to prevent contamination and fire risk
Nitrogen blanketing supplies a continuous flow of nitrogen above the cargo surface to maintain an inert atmosphere, protecting reactive or flammable cargoes from air and moisture.