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Mech Theory > Auxiliary systems > Flashcards

Auxiliary systems Flashcards

1
Q

Describe the HPSWM

A

High pressure salt water main, a system of ready to use salt water in a ring main around 2 deck maintained by electronic pumps in the lower decks of the ship.

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2
Q

What pressure is held in the HPSWM?

A

7 Bar or 100-120 PSI

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3
Q

Describe the path the saltwater takes in the HPSWM

A

Through a strainer
Via an electronic pump in the lower decks
Upwards through a riser to the ring main

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4
Q

How is the pressure maintained in the HPSWM?

A

There is a 10% overpressure leak off and pressure relief valves as back up

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5
Q

What is high pressure salt water used for?

A
  • Firefighting
  • Pre-wetting
  • Fitted bilge and salvage eductors
  • Emergency cooling to GT and Diesel Engines
  • Auxiliary machinery cooling water system
  • Making of fresh water
  • Flushing Heads (on a few ships)
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6
Q

Describe damage control state one - HPSWM

A

Damage likely - individual pumps supply own sections of ringmain. Ringmain isolated by shutting the state valves to minimise effects of damage.

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7
Q

Describe damage control state three- HPSWM

A

Normal operating state - one pump supplies ring main with another on standby should pressure drop. All main isolating valves are open.

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8
Q

What coolant is used in the engine?

A

Fresh water and AL39 mix

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9
Q

Why is fresh water used in cooling rather than salt water?

A

Machinery is susceptible to salt water corrosion
Machinery can be affected by salt water contamination

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10
Q

Why does machinery need to be cooled?

A

Uncooled machinery can cause fire, seizing equipment failure and wiping of bearings (white metal bearing melt at 115 degrees if exceeded bearing will wipe)

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10
Q

Why does machinery need to be cooled?

A

Uncooled machinery can cause fire, seizing equipment failure and wiping of bearings (white metal bearing melt at 115 degrees if exceeded bearing will wipe)

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11
Q

Which part of the cooling system is
1) closed loop
2) open loop?

A

1) Lubrication/AL39 system
2) Cooling circulation system - salt water for heat exchange

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12
Q

What machinery is supplied by the main propulsion cooling system?

A
  • Lub Oil heat exchanger
  • Gas turbine heat exchanger
  • CPP unit heat exchanger
  • Plummer block heat exchanger
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13
Q

What system is in place to allow the cleaning of the salt water strainer?

A

Cross connection from the opposite side e.g connecting port salt water to STBD

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14
Q

What machinery is supplied by the Aux circ system?

A

Air conditioning plant
Diesel plant/generators

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15
Q

Who’s permissions is required to connect the fresh water circulation system to salt water system in an emergency?

A

MEO

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16
Q

What are the Marpol regulations for discharge of water within 12NM from land?

A
  • oil content must not exceed 15PPM
  • Ship must be underway
  • Ship has an oily water separating filter and discharge monitoring system
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17
Q

What are the Marpol regulations on discharge of water over 12 NM from land?

A
  • Oil content does not exceed 15PPM
  • The ship is underway
  • The ship has in operation oil water filter
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18
Q

What are the special areas as defined by the IMO?

A

Baltic sea
North west European waters
Mediterranean sea
Black sea
Gulf
Gulf of Aden
Caribbean

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19
Q

What are the main sources of oil contamination?

A

Bilges
Fuel systems
Oil Systems
CPP systems

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20
Q

Safe systems of work to prevent oil entering bilge?

A

Keep machinery spotless
Monitor lube oil ready use tanks and investigate any loses
No surfactants used (Kleen break only)
AFFF only used in real fire situations
Eductors to be manned when in operation
Maximise use of alongside facilities when alongside

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21
Q

Where is black water from?

A

WC’s
Urinals
WC scuppers
Medical Compartment
any water mixed with the above

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22
Q

When can black water be discharged?

A

within 4NM of coast (only permitted with an IMO approved sewage treatment plant)
4NM < 12NM only IMO approved system to comminute and disinfect the sewage is in opperation
Over 12NM from shore no regulations

23
Q

Where is grey water from?

A

Bathrooms
Galleys
Dishwasher
Laundries
Sinks

24
Q

What regulations are there on grey water discharge

A

No regulation unless - alongside or entering and leaving port

25
Q

Describe the vacuum pump

A

Comprises of fitted for ship diesel or electronic pumps, manifolds and hoses which disposed of all black and grey water. Water discharges can be collected and discharged to avalible shore facility.

26
Q

Describe the bilge

A

Spillage, leakage or condensation that accumulates at the bottom of the hull

27
Q

What is sullage?

A

The left over fluids/sludge after bilge water has been passed through a separator

28
Q

What are eductors used for?

A

Eductors are used to quickly remove quantities of fluid from the bilges very quickly.
Uses the HPSW system and the Bernoulli’s theory to cause a depression and drag the water out.

29
Q

What does the bilge and sullage system do?

A
  • Bilge system is fitted to remove excess fluid from machinery system - separate water from oil and water discharged overboard
  • Sullage system retains dirty waste oil or fuel until it can be properly discharged ashore.
30
Q

How would you operate the eductor?

A

1) Open the discharge overboard
2) Open the motive water valve from the HPSWM
3) Open the bilge suction valve

This can only be done with the MEO’s permission and if done in the wrong order will flood the bilge.

31
Q

What health issues hazards are associated with raw sewage?

A
  • Typhoid
  • Hepatitis
  • Gastro-enteritis
32
Q

What are the advantages of using a Sewage Treatment Plant?

A

Reduce number of side openings
Simplify pipe runs
Heads and bathrooms can be lower on ship
Heads and bathrooms can be used in dry dock
Ship can operate in anti-pollution areas
Its easier to close down in CBRN conditions

33
Q

Explain the operation of the biological Sewage treatment plant

A

1) raw sewage passed into the aeration chamber via a macerator and coarse screen to remove large particles.
2) The aeration diffusers pass oxygen through the waste to allow its aerobic digestion.
3) Undigested waste sinks to the bottom and digested waste floats the top, the air lift pump transfers the digested waste to the settlement hopper
4) Heavy sludge sinks to the bottom and is transferred back to the aeration tank via the sludge return tube.
5) Digested waste floats and weirs into the chlorine contact tank where it’s disinfected and then weirs to the collection tank.
6) Mixed with the grey water to dilute the chlorine and disinfect the grey water.

34
Q

Why is it important to ensure sewage digestion is aerobic?

A

If not microorganisms will die giving off Hydrogen Sulphide which is a toxic gas which smells like rotten eggs

35
Q

At what PPM is Hydrogen sulphide detectable by smell

A

0.03

36
Q

At what PPM does Hydrogen Sulphide odour become less detectable

A

above 30 PPM

37
Q

What effect does 70-150PPM hydrogen sulphide have on humans

A

Kills sense of smell in around 3-15 mins - irritates eyes, throat and lungs

38
Q

What ppm hydrogen sulphide is an immediate threat to life (rapidly produces unconsciousness and permanent brain damage possible)?

A

700-1000PPM

39
Q

Over 1000PPM hydrogen sulphide cause what?

A

Immediate unconsciousness and death withing seconds

40
Q

What hazards are associated with Methane and Chlorine gas?

A

Methane - is flammable and risk of explosion

Chlorine - if inhaled will burn the lungs and can be fatal

41
Q

List the 3 main hazard categories around sewage?

A

Chemicals
Raw Sewage
Gasses

42
Q

Describe how the collect hold and transfer system works

A

1) Specialist pumps draw a vacuum on an initial collection tank which connects to the wc by pipework that is also under vacuum.
2) Press of flush permits the content of the wc to be drawn into the collection tank
3) Working via the use of level switches when the tank reaches a set level a combined discharge/transfer pump which transfers sewage to large holding tanks
4) The sewage is then held here until discharged to sea or a land based treatment centre
5) Whilst being held the sewage is transferred between the tanks to aerate the sewage and prevent anaerobic digestion.

43
Q

What system is used when a ship fitted with a CHT system when in dock?

A

Vacuum pumping system is used to transfer the black and grey water to shore system.

The rigging of which is normally performed by contractors should the ship be in port for less than 72Hrs or ME with all sections taking 20 personnel around 3Hrs

44
Q

What PPE machinery would be needed to work in a Hydrogen Sulphide risk area

A

A H2S monitor e.g. a leader gas monitor. Turned on before entering the compartment

45
Q

What precautions are related to working with sewage?

A

Medical Protection - Inoculations to be given to those working and any injury to be treated by sickbay
Personal Hygiene - must be scrupulous and no hand to mouth contact before thoroughly washing
PPE must be worn - Minimum gloves, mask, goggles or face shield and overalls
Monitor atmosphere - leader or sega monitor

46
Q

What are the advantages of compressed air?

A
  • Easy to distribute
  • Easily stored
  • Flexibility and reliability of use
  • Low risk of fire
47
Q

What are the 2 HP air categories?

A
  • HP air at 276 bar (4000Psi)
  • Reduced pressure air below 276 Bar as required by specific equipment
48
Q

What are the 2 HP air operating areas?

A
  • IMS (inside machinery space)
  • OMS (outside machinery space)
49
Q

List the uses for high pressure air

A
  • Diesel engine starting
  • Gas turbine starting
  • Ship siren operation
  • Breathing apparatus charging
  • Weapons system operation
  • Hydraulic system accumulator charging
  • Air driven machinery operation
  • Cross connection to low pressure air system (276 -> 8 bar)
50
Q

What are the 4 pressures in a 4 stage HPAC?

A

1 - 4 bar
2 - 17.5 bar
3 - 68 Bar
4 - 276 Bar

51
Q

What are the 4 pressure relief valves (10% over pressure valves) set?

A

1 PRV - 4.4 Bar
2 PRV - 19.25 Bar
3 PRV - 74.9 Bar
4 PRV - 303.6 Bar

52
Q

What warnings and stoppages could you expect on a HPAC?

A
  • High Water pressure (54C)
  • Low oil Pressure (0.69Bar)
53
Q

What is LP air used for?

A
  • Pneumatic tools
  • Radar wave guides
  • Emergency stern seal inflation
  • Pneumatic surveillance panels
54
Q

What are the hazards when working with HP/LP air?

A
  • HP air directed towards the body can cause air pockets in bloody stream which can be lethal
  • Dieseling - Grease or oil can explode when brought into contact with high pressure air
  • Flailing hose lines
55
Q

What precautions should be followed when using high pressure air?

A
  • Don’t direct air towards the body
  • PPE - ear defenders and goggles
  • Silicone grease used to prevent the risk of dieseling
  • Flexible hoses must be “whipped” (bound and tied) to prevent flailing
  • Air hoses are dated with an expiry date.
56
Q

What are the safe working practises when filling air bottles?

A
  • Bottles located on purpose built rack
  • Operators must be wearing appropriate PPE (goggles and ear defenders)
  • Hoses in good condition and connected using the correct spanner
  • Good condition O seal to be used
  • Bottle should be filled slowly to prevent overheating.

Mech Theory (1 decks)

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