武汉理工大学：《船舶辅机》课程教学资源（PPT课件，英文版）1.9 Domestic fresh and salt watersystems

1.9 Domestic fresh and salt water systems Open systems using gravity tanks, etc, are rarely met nowadays and figure 1. 8 shows a characteristic arrangement of pressure tanks, calorifiers and pumps for a large ship. The fresh water pumps are self-priming drawing from storage tanks and discharging through filters to a rising main, branched to give a cold supply and a hot supply in closed circuit through a calorifier. a tank kept under pressure by an external supply of compressed air rests on the system and provides the head necessary for constant supply throughout the ship

1.9 Domestic fresh and salt water systems • Open systems using gravity tanks, etc., are rarely met nowadays and Figure 1.8 shows a characteristic arrangement of pressure tanks, calorifiers and pumps for a large ship. The fresh water pumps are self-priming, drawing from storage tanks and discharging through filters to a rising main, branched to give a cold supply and a hot supply in closed circuit through a calorifier. A tank kept under pressure by an external supply of compressed air rests on the system and provides the head necessary for constant supply throughout the ship

1.9 Domestic fresh and salt water systems The pump starters are controlled by pressure switches which operate when the pressure in the tank varies within predetermined limits as water is drawn off. Distilled water in now largely used in board; this may be corrosive ( due to the presence of dissolved co2)and flat to the taste. It is not unusual to provide for the introduction of certain chemicals, e.g. Calcium Chloride(Cacl2)and Sodium Bicarbonate(2NaHCO3)which, in solution are converted to Calcium Bicarbonate( Ca(hCo3 )2)and Sodium Chloride(2Naci)to render the water neutral and palatable. It may then be chlorinated to ensure bacteriological purity and subsequently de-chlorinated Figure 1. 9 shows such a system diagrammatically

1.9 Domestic fresh and salt water systems • The pump starters are controlled by pressure switches which operate when the pressure in the tank varies within predetermined limits as water is drawn off. Distilled water in now largely used in board; this may be corrosive (due to the presence of dissolved CO2) and flat to the taste. It is not unusual to provide for the introduction of certain chemicals, e.g. Calcium Chloride (CaCl2) and Sodium Bicarbonate (2NaHCO3) which, in solution are converted to Calcium Bicarbonate (Ca(HCO3)2) and Sodium Chloride (2NaCl) to render the water neutral and palatable. It may then be chlorinated to ensure bacteriological purity and subsequently de-chlorinated. Figure 1.9 shows such a system diagrammatically

1.9 Domestic fresh and salt water systems It is not unusual to provide for the introduction of certain chemicals, e.g. Calcium Chloride(CaC12) and Sodium Bicarbonate(2NaHCO3)which, in solution are converted to calcium bicarbonate (Ca(HCo3 )2) and Sodium Chloride(2Naci)to render the water neutral and palatable. It may then be chlorinated to ensure bacteriological purity and subsequently de-chlorinated. Figure 1. 9 shows such a system diagrammatical

1.9 Domestic fresh and salt water systems • It is not unusual to provide for the introduction of certain chemicals, e.g. Calcium Chloride (CaCl2) and Sodium Bicarbonate (2NaHCO3) which, in solution are converted to Calcium Bicarbonate (Ca(HCO3)2) and Sodium Chloride (2NaCl) to render the water neutral and palatable. It may then be chlorinated to ensure bacteriological purity and subsequently de-chlorinated. Figure 1.9 shows such a system diagrammatically

1.9 Domestic fresh and salt water systems The salt water pump(s) need not be self-priming nor are heating nor treatment required otherwise the system is identical Domestic fresh and salt water systems →

1.9 Domestic fresh and salt water systems • The salt water pump(s) need not be self-priming, nor are heating nor treatment required, otherwise the system is identical. Domestic fresh and salt water systems

↓- Air cock HFw return C F.W. main H F W. flow C F.W. to H F.W. flow calorifier i sW.『sing Air cock H F.W. return C.F.W. rising main I main Pressure Sluice valve Prepress switches S: W. tank i.R. valve Calorifier Shut -off valve shut-off i Fire and t-SDNR Valve valve wash" deck Pneypress F.W. tank rIsIng main N.R. Valve supply i S D.l. valv 91 litre Shut-off/Air P ressure calorifier switches valve filter Change over for aft SWItC accommodation Reducing alve F.W. filters Change over: switch Pump'A'l/Pump'B Pump A Pump B Starter 'A/starter 'B"/Starter A>/Starter B Non-return valve Non-return valve Non-return valve F W. pumps Sanitary pumps

End of chapter 1

End of Chapter 1