Question 40 TK01 - Tank Vessel Assistant - Dangerous Liquids

The Correct Answer is C ### Explanation for C (90%) The requirement for setting the high-pressure alarm in the main vapor collection line of an inert gas system is mandated by international regulations (specifically SOLAS and the IMO Inert Gas System Code, or IGS Code). These regulations ensure that the pressure within the cargo tanks and associated piping remains safe and below the design limits, particularly before the pressure relief valves (PV valves) are activated. The alarm must sound at a pressure that is high enough to indicate a problem (e.g., excessive inert gas delivery or blocked venting) but low enough to allow the crew time to intervene before the lowest pressure/vacuum relief valve (PV breaker or main PV valve) opens and potentially vents flammable vapors. The relevant requirement specifies that the high-pressure alarm in the inert gas main must be set to activate at a pressure not exceeding **90%** of the lowest setting of any pressure relief valve installed on any cargo tank protected by the system. ### Explanation for Incorrect Options * **A) 70%:** While 70% would provide a very early warning, it is unnecessarily conservative and does not align with the regulatory standard. Setting the alarm this low might lead to nuisance alarms during normal operations when the system is operating safely just below the regulatory threshold. * **B) 80%:** Similar to 70%, 80% is a safe margin but is not the mandated maximum pressure threshold defined by the IGS Code for this specific alarm function. The intention is to warn just before the safety devices (relief valves) are about to activate. * **D) 95%:** Setting the alarm at 95% would be too close to the actual relief valve setting. This reduces the margin for error and the time available for the crew to take corrective action before the relief valve activates. The regulation strictly prohibits setting the alarm higher than 90% of the lowest relief valve pressure.