Question 48 OSE01 - Chief Engineer - OSV

The Correct Answer is B **Explanation for Option B (Daily):** In shipboard and offshore machinery systems, especially those utilizing compressed air for critical operations like starting main or auxiliary engines (diesel engines), the presence of moisture in the air system is detrimental. Moisture leads to corrosion, washes away lubricant, and can freeze or obstruct small passages, causing control valves or starting mechanisms (like vane-type motors) to fail. Moisture separators (or air filters/drains) are designed to remove this water. Best operational practice, standardized across many maritime bodies and operational manuals (including guidance for auxiliary machinery maintenance), dictates that moisture separators and air reservoirs should be drained frequently—at least once per 24-hour period (daily)—to prevent excessive water accumulation when automatic drains are not installed or are non-functional. During routine watch turnover or engine room rounds, draining these separators is a standard requirement. **Explanation of Incorrect Options:** * **A) Hourly:** While draining hourly would ensure the system is extremely dry, it is excessively frequent for standard operational rounds and maintenance procedures. Unless the air compressor is running almost continuously in extremely humid conditions and the separator is undersized, hourly draining is generally unnecessary and consumes valuable crew time inefficiently. * **C) Weekly:** Draining only once a week is insufficient. Depending on the ambient humidity and the frequency of air compressor operation (especially on an active offshore supply vessel which uses air frequently for starting and control), enough water could accumulate over several days to cause significant corrosion or operational failure in the air starting motors or downstream controls before the weekly drain is performed. * **D) Monthly:** Draining monthly is far too infrequent. High levels of moisture accumulation and the resulting damage (corrosion, lubricant washout) would be almost guaranteed in a continuously operating marine environment if the drains were only cleared every 30 days. This practice would violate basic safety and maintenance standards for critical engine starting systems.