The general service pump is to be used to remove clean water from the No. 3 port double-bottom cofferdam and discharge it through the ballast overboard discharge. What are the minimum number of valves, shown in the illustration, that must be opened on both the suction and discharge to accomplish this task? See illustration GS-0042.
• Follow the complete suction path from the No. 3 port double-bottom cofferdam all the way to the general service pump inlet on the diagram. • Follow the discharge path from the pump outlet to the ballast overboard discharge, noting each valve that must be open to make a continuous path. • Remember the word minimum – ignore valves that branch to other systems or tanks if they don’t have to be opened for this specific transfer.
• Starting at the No. 3 port double-bottom cofferdam symbol, how many individual valves must be open before water can actually reach the general service pump suction flange? Trace them one by one with your finger on the drawing. • From the pump discharge, which single route leads most directly to the ballast overboard discharge, and how many valves along that route must be open to reach the sea? • Are there any valves in parallel or on alternate branches that you can leave closed while still providing an open path from cofferdam to overboard? If so, don’t count them.
• Verify that you have counted only valves that sit directly in the flow path from the cofferdam to the overboard discharge – no side branches. • Double‑check that you have included valves immediately at the cofferdam, at the suction manifold, at the pump suction and discharge, and at the final overboard/sea valve. • Confirm that each segment of the line (cofferdam → suction line → pump → discharge line → overboard) has at least one open isolation valve so there is an unbroken flow path.
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