Question 28 MODE02 - Assistant MODU Engineer

The Correct Answer is B ### Explanation of Correct Option **B) Measure cylinder compression or firing pressures** The instrument referenced in marine or mechanical engineering contexts for monitoring the internal pressures of a diesel engine—often a Peak Pressure Indicator (like a Maihak Indicator or a modern digital indicator)—attaches directly to the indicator cock on the cylinder head. * **Function:** Its primary purpose is to measure the maximum pressure developed during the compression stroke (compression pressure) and the maximum pressure developed after combustion (firing pressure or peak pressure). * **Engine Health:** These readings are crucial for diagnosing engine performance, monitoring cylinder balance, ensuring proper fuel injection timing, and detecting issues like worn piston rings, leaking valves, or faulty injectors. ### Explanation of Incorrect Options **A) Measure exhaust gas pressure** Exhaust gas pressure is measured in the exhaust manifold, typically using a simpler gauge or manometer connected to a dedicated test point in the manifold itself, not via the indicator cock on the cylinder head. **C) Measure concentration of chromate in jacket water** Chemical analysis (like measuring chromate concentration, a common corrosion inhibitor) requires specialized chemical test kits, titration equipment, or laboratory analysis. It is completely unrelated to the function of a mechanical pressure-measuring instrument. **D) Balance exhaust gas temperature readings** While monitoring cylinder pressure helps determine engine balance, the instrument itself measures pressure, not temperature. Exhaust gas temperature readings are measured by pyrometers and thermocouples. Balancing the engine is achieved by adjusting fuel settings and timing based on *both* temperature and pressure data.