Section 6 Drainage units on dewatering service and their connections

6.1.1 At least three power pumps for supply of water to eductors are to be provided in the machinery spaces.

6.1.2 Dewatering eductors may take suction from a suction main with branches to individual spaces or directly to individual spaces or a combination of systems.

6.2.1 The power pumps, required by Vol 2, Pt 7, Ch 2, 6.1 Number of pumping units may also be used for ballast, fire or general service duties of an intermittent nature, but not for pumping fuel or other flammable liquids. These pumps are to be immediately available for dewatering duty when required.

6.3.1 The capacity of each pump required by Vol 2, Pt 7, Ch 2, 6.1 Number of pumping units 6.1.1 is to be sufficient to supply the eductor capacities required by Vol 2, Pt 7, Ch 2, 6.3 Capacity of pumps and educators 6.3.2 and capable of providing water to eductors in any two compartments. Where the piping system supplying the eductors is used for other purposes, the capacity of the pumps is to be sufficient for those additional services.

6.3.2 The capacity of dewatering eductors is to be not less than required by the formulae in Vol 2, Pt 7, Ch 2, 6.3 Capacity of pumps and educators 6.3.3 or Vol 2, Pt 7, Ch 2, 6.3 Capacity of pumps and educators 6.3.4.

6.3.3 Where the eductor is connected to a suction main serving more than one compartment:

In general, the capacity is to be not less than 75m³/hr for ships over 100 m length.

6.3.4 Where an eductor is connected to a single suction in a machinery space or other space located below the damage waterline, the capacity is to be not less than:

6.3.5 The capacity of eductors for spaces other than required by Vol 2, Pt 7, Ch 2, 6.3 Capacity of pumps and educators 6.3.3 and Vol 2, Pt 7, Ch 2, 6.3 Capacity of pumps and educators 6.3.4 is in general to be not less than 15 m³/h.

6.4.1 The connections at the power pumps and eductors are to be such that one unit may continue in operation when the other unit is being opened up for overhaul.

6.4.2 Pump units required for Mobility systems or Ship Type systems are not to be connected to a common suction or discharge chest or pipe unless the arrangements are such that the working of any units so connected is unaffected by the other units being in operation at the same time.