High Pressure Salt Water System Flashcards
What is the HPSW operating pressure?
7 bar
What is fitted to prevent system over pressurisation?
Relief valves and 10% leak off valves maintain the pressure at 7 bar
State six uses of HPSW
Probably only 4 to 5
- Firefighting - hydrants/sprays/centre feed hose reels
- Pre Wetting system
- Fitted Bilge and Salvage Eductors
- Emergency Cooling to main propulsion gas turbines/diesel generators
- Auxilliary Machinery cooling water system
- Making of fresh water
- Flushing heads (on some types of ship)
Explain the flow of SW from the Sea to the Ringmain
supplied by electrically driven pumps, taking suction from the sea through a strainer, and connected to the ring main via a “riser”.
Explain the HPSW Ringmain
7 bar (100-120 PSi) to a ring main system. It usually runs around 2 deck
How are the HPSW pumps driven and where can they be operated from?
Driven by electric pumps and can be operated locally (at the pump control box) or remotely (SCC or Machinery Control Room MCR)
Where will HPSW sprays be located?
- Funnel
- magazines
- paint lockers
- inflam store
Explain the Pre-Wet system
Operated in an NBC (nuclear biological contamination) environment to reduce contamination levels of the upper decks. Decks are sprayed and ship moves side to side to wash off decks
Explain the system configuration in DC State 1
At DC State 1 individual HPSW pumps supply their own section of the ringmain. The ringmain is isolated by shutting the state valves to minimise effects from damage
Explain the system configuration in DC State 3
All main isolating/state valves open, with one pump supplying the whole system. Should system pressure drop a second pump can be started
When may more pumps be introduced?
When more pressure is needed to the ringmain, dropped below 7 bar
