3-5: DC Systems Flashcards
Purpose of FM
supplies seawater to firehose stations, AFFF, sprinklers, etc
FM design features
Multiple independent pumps, redundant water paths, ability to segregate, remote operation
When the discharge pressure at a fire pump is higher than its design pressure rating, the flow from the pump is _______ than its design flow rating. At low flows, the pump will _______, leading to stress on the bearings, seals, and pump mechanical seals, and possibly premature failure.
lower, vibrate
How do you lower FM pressure and increase the flow?
reduce the number of pumps online, or place additional ship’s services online without adding pumps.
During normal operation, a pressure ________ is a result of starting a pump or securing ship’s services. Closing a main segregation or COV can also cause _____ pressure, because the closed valve can block water flow from the pump.
increase, high
When the flow from the fire pump is higher than its design flow rating, the discharge pressure at the pump is _______ than its design pressure rating.
lower
What conditions can cause a FM fault?
large demand, pump failure, piping rupture
Purpose of casualty power system
provides temporary power if installed systems are damaged
Design features of casualty power
preservation of watertight integrity, interchangeability of parts, simplicity
When rigging casualty power, who designates source switchboard & riser, who establishes casualty power route, who is the final authority to energize?
Source: EO, Route: DCA, Final Authority: DCA (per the manual, but could be CO depending on the boat)
What chapter of the repair party manual is related to casualty power and what type of info does it provide?
Ch 6, sect 3: Casualty Power Bill (preplanned routes), casualty power checklist, electrical damage checklist,
Three types of shipboard ventilation and their function
supply (take fresh air from the weather and deliver it inside the ship), exhaust (take stale, hot air from inside the ship and exhaust it overboard), recirculation (provide air conditioning to a space or group of spaces by recirculating and tempering (i.e., in heating or cooling) the air within the space)
What two DC diagrams are associated with ventilation?
1) supply/recirc: blue-mech supply fans, closures, ducts; orange-natural supply/exhaust closures; red-recirculation
2) exhaust: green-fans, closures, ducts; orange-natural supply/exhaust closures
Purpose of Smoke Ejection System (SES)
sweep smoke from pways on DC deck and main deck around medical spaces
What are the principle systems affecting DC operations onboard ship?
FM, ventilation, casualty power
