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Seawater cooling pumps

The pumps are to be of the centrifugal type.

The capacity is to be within a tolerance of 0% to +10%.

The differential pressure of the pumps is to be determined on the basis of the total actual pressure drop across the cooling water system.

Central cooler

The cooler is to be of the shell and tube or plate heat exchanger type, made of seawater resistant material.

Pressure drop on central cooling side.....max. 0.2 bar

The pressure drop may be larger, depending on the actual cooler design.

The heat dissipation and the seawater flow figures are based on MCR output at tropical conditions, i.e. a seawater temperature of 32 °C and an ambient air temperature of 45 °C.

Overload running at tropical conditions will slightly increase the temperature level in the cooling system, and will also slightly influence the engine performance.

Central cooling water pumps

The pumps are to be of the centrifugal type.

The flow capacity is to be within a tolerance of 0% to +10%.

The list of capacities covers the main engine only. The differential pressure provided by the pumps is to be determined on the basis of the total actual pressure drop across the cooling water system.

Central cooling water thermostatic valve

The low temperature cooling system is to be equipped with a three way valve, mounted as a mixing valve, which by passes all or part of the fresh water around the central cooler.

The sensor is to be located at the outlet pipe from the thermostatic valve and is set so as to keep a temperature level of minimum 10 °C.

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

Jacket water system

Due to the central cooler the cooling water inlet temperature is about 4 °C higher for for this system compared to the seawater cooling system.

The input data are therefore different for the scavenge air cooler, the lube oil cooler and the jacket water cooler.

The heat dissipation and the central cooling water flow figures are based on an MCR output at tropical conditions, i.e. a maximum seawater temperature of 32 °C and an ambient air temperature of 45 °C.

The flow capacity is to be within a tolerance of 0% to +10%.

The stated of capacities cover the main engine only. The pump head of the pumps is to be determined on the basis of the total actual pressure drop across the cooling water system.

Scavenge air cooler

The scavenge air cooler is an integrated part of the main engine.

Page of 2

Lubricating oil cooler

See chapter 8 ‘Lubricating Oil’.

Jacket water cooler

The cooler is to be of the shell and tube or plate heat exchanger type.

The other data for the jacket cooling water system can be found in chapter 12.

For further information about a common cooling water system for main engines and MAN Diesel auxiliary engines, please refer to our publication:

Uni concept Auxiliary Systems for Two stroke Main

The publication is available at www.mandiesel.com under ‘Quicklinks’ → ‘Technical Papers’

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

3EAWATER PUMPS

4HERMOSTATIC

VALVE

3EAWATER OUTLET

3EAWATER INLET

3EAWATER INLET

The letters refer to list of ‘Counterflanges’

Fig. 12.02.01: Seawater cooling system

The seawater cooling system is used for cooling, the main engine lubricating oil cooler, the jacket water cooler and the scavenge air cooler, see Fig. 12.02.01.

The lubricating oil cooler for a PTO step up gear should be connected in parallel with the other coolers. The capacity of the seawater pump is based on the outlet temperature of the seawater being maximum 50 °C after passing through the coolers – with an inlet temperature of maximum 32 °C (tropical conditions), i.e. a maximum temperature increase of 18 °C.

The valves located in the system fitted to adjust the distribution of cooling water flow are to be provided with graduated scales.

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The inter related positioning of the coolers in the system serves to achieve:

•The lowest possible cooling water inlet temperature to the lubricating oil cooler in order to obtain the cheapest cooler. On the other hand, in order to prevent the lubricating oil from stiffening in cold services, the inlet cooling water temperature should not be lower than 10 °C

•The lowest possible cooling water inlet temperature to the scavenge air cooler, in order to keep the fuel oil consumption as low as possible.

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

MAN B&W K108ME C6, K98MC/MC C6/7, K98ME/ME C6/7, S90MC-C7/8, S90ME C7/8, K90MC-C6, K90ME9, K90ME-C6/9

Seawater cooling pump

The pumps are to be of the centrifugal type.

The capacity must be fulfilled with a tolerance of between 0% to +10% and covers the cooling of the main engine only.

Lubricating oil cooler

See chapter 8 ‘Lubricating Oil’.

Jacket water cooler

The cooler is to be of the shell and tube or plate heat exchanger type, made of seawater resistant material.

The heat dissipation and the seawater flow are based on an MCR output at tropical conditions, i.e. seawater temperature of 32 °C and an ambient air temperature of 45 °C.

Scavenge air cooler

The scavenge air cooler is an integrated part of the main engine.

The heat dissipation and the seawater flow are based on an MCR output at tropical conditions, i.e. seawater temperature of 32 °C and an ambient air temperature of 45 °C.

Seawater thermostatic valve

The temperature control valve is a three way valve which can recirculate all or part of the seawater to the pump’s suction side. The sensor is to be located at the seawater inlet to the lubricating oil cooler, and the temperature level must be a minimum of +10 °C.

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

The jacket cooling water system is used for cooling the cylinder liners, cylinder covers and exhaust valves of the main engine and heating of the fuel oil drain pipes, see Fig. 12.05.01.

The jacket water pump) draws water from the jacket water cooler outlet and delivers it to the engine.

At the inlet to the jacket water cooler there is a thermostatically controlled regulating valve, with a sensor at the engine cooling water outlet, which keeps the main engine cooling water outlet at a temperature of 80 °C.

The engine jacket water must be carefully treated, maintained and monitored so as to avoid corrosion, corrosion fatigue, cavitation and scale formation. It is recommended to install a preheater if preheating is not available from the auxiliary engines jacket cooling water system.

The venting pipe in the expansion tank should end just below the lowest water level, and the expansion tank must be located at least 5 m above the engine cooling water outlet pipe.

The freshwater generator, if installed, may be connected to the seawater system if the generator does not have a separate cooling water pump. The generator must be coupled in and out slowly over a period of at least 3 minutes.

For external pipe connections, we prescribe the following maximum water velocities:

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

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MAN B&W S90MC-C7/8, S90ME C7/8, K90MC-C6, K90ME9, K90ME C6/9, S80MC-C7/8, S80ME C7/8/9, K80MC-C6, K80ME C6/9