1.2 Circulating water systems In motorships there are two main circuits, one salt, one fre esh .g The salt circuit is: sea inlet box(seachest)-pump(s f w. coolers in series(first LT then HT)-turbo blower aftercoolers in parallel (if any)-provision condenser in parallel (if any)-overboard .g Branches(not be shown in Fig ) may be taken to blower oil coolers, fuel valve cooling oil coolers and from the outlet side, to evaporator sea inlets or domestic warm water systems, baths, etc .g There may be a blanked connection to the fresh water circuit
1.2 Circulating water systems ❖ In motorships there are two main circuits, one salt , one fresh. ❖ The salt circuit is: sea inlet box (seachest) - pump(s) - f.w. coolers in series (first LT then HT) – turbo blower aftercoolers in parallel (if any) – provision condenser in parallel (if any) - overboard. ❖ Branches (Not be shown in Fig.) may be taken to blower oil coolers, fuel valve cooling oil coolers and from the outlet side, to evaporator sea inlets or domestic warm water systems, baths, etc. ❖ There may be a blanked connection to the fresh water circuit
1.2 Circulating water systems .g The fresh water circuit being under positive head is closed, i.e. pump-fresh water coolers-cylinder jackets-cylinder heads-exhaust valves(if any) turbo-blowers (if any),-pump inlet There may be closed circuit branch to evaporator primary-stage heating inlets .g If the engine pistons are water-cooled, the circuit may be in parallel with the jacket circuit; it is more likely to be separate, the circuit being pump-cooler-inlet manifold- telescopic tubes outlet manifold- pump
1.2 Circulating water systems ❖The fresh water circuit being under positive head , is closed, i.e. pump-fresh water coolers - cylinder jackets - cylinder heads - exhaust valves (if any) – turbo – blowers (if any), - pump inlet. ❖There may be closed circuit branch to evaporator primary-stage heating inlets. ❖If the engine pistons are water-cooled, the circuit may be in parallel with the jacket circuit; it is more likely to be separate, the circuit being: pump – cooler - inlet manifold- telescopic tubesoutlet manifold- pump
1.2 Circulating water systems The f w temperature should be kept as high as practicable by the use of the salt water 2 Lt bypass valves on oil and f w coolers N o These may be butterfly valves controlled by thermo-pneumatic d evices
1.2 Circulating water systems ❖ The f.w. temperature should be kept as high as practicable by the use of the salt water bypass valves on oil and f.w. coolers. ❖ These may be butterfly valves controlled by thermo-pneumatic devices
1.2 Circulating water systems It is usual to provide for sh warming the ires circulating water before the main engines are started either by steam or more usually, by bleeding from the auxiliary fresh cooling circuit
1.2 Circulating water systems ❖ It is usual to provide for warming the fresh circulating water before the main engines are started, either by steam or more usually, by bleeding from the auxiliary fresh cooling circuit
1.2 Circulating water systems a The air compressor inter-and after-coolers are likely to be supplied in parallel It is unusual for supercharger blowers to have aftercoolers: if they have they will be circulated SImilarly The auxiliary fresh water system is similar to the main and may use the same header tank if the resulting head is not too great; if it is, a separate header tank will be provided
1.2 Circulating water systems ❖ The air compressor inter-and after- coolers are likely to be supplied in parallel; ❖ It is unusual for supercharger blowers to have aftercoolers; if they have, they will be circulated similarly. ❖ The auxiliary fresh water system is similar to the main and may use the same header tank if the resulting head is not too great; if it is, a separate header tank will be provided
1.2 Circulating water systems If the pumps for each service are not duplicated they will be dual-connected .g If one pump fails, the survivor becomes the fresh water pump and a clean service e.g. ballast pump circulates the sea water EM,BILGE SCT. PUMP INERT GAS LPGo00L形Ps 1 TO C4S 伪→西 HANDLING PLANE ROM VATE RAY SYS
1.2 Circulating water systems ❖ If the pumps for each service are not duplicated, they will be dual-connected. ❖ If one pump fails, the survivor becomes the fresh water pump and a clean service e.g. ballast pump circulates the sea water
