Question 61 OSE02 - Assistant Engineer - OSV

The Correct Answer is B **Explanation for Option B (Correct Answer):** The illustration MO-0194 typically depicts a hot water heating system utilizing a fired boiler (heating plant) on a vessel, often for accommodations, tanks, or process heating. * **Circulating Pump (or Distribution Pump):** This pump is responsible for moving the heated water from the boiler, through the distribution loops (e.g., radiators, heat exchangers), and back to the boiler. To maintain consistent heating, the circulating pump must run **continuously** whenever the system is operational, ensuring constant heat transfer throughout the vessel. * **Feed Pump (or Makeup Pump):** The heating system is a closed loop, meaning it does not consume water under normal operation. The feed pump is used only to replenish water lost due to minor leaks, venting, or maintenance procedures. It draws water from a header or storage tank and pumps it into the system to maintain the required pressure. Therefore, the feed pump runs **intermittently**, usually activated automatically by a low-pressure sensor or manually when makeup water is required. **Explanation of Incorrect Options:** * **A) The circulating pump runs intermittently and the feed pump runs continuously.** This is incorrect. The circulating pump must run continuously to distribute heat, and the feed pump runs only as needed (intermittently) to replace lost water. * **C) The circulating and feed pumps both run intermittently.** This is incorrect. If the circulating pump ran intermittently, heating would be sporadic and inconsistent. Only the feed pump runs intermittently. * **D) The circulating and feed pumps both run continuously.** This is incorrect. Running the feed pump continuously would rapidly over-pressurize the closed heating system, leading to relief valve lifting and system water loss. Only the circulating pump runs continuously.