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ETICC > Mech theory 3 > Flashcards

Mech theory 3 Flashcards

1
Q

The HPSWM maintains how much bar to a ring main system and what deck does it run around?

A

7 bar

Usually deck 2 on some types of ship deck 5

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2
Q

How is the High pressure salt water system supplied?

A

Supplied by electrically driven pumps that take suction from the sea through a strainer and connected to the ring main via a riser.

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3
Q

What maintains the pressure in the HPSWS?

A

Relief vales and 10% leak off valves

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4
Q

The uses of the HPSWS

A 
Firefighting e.g. hydrants
Pre wetting system
fitted bilge and salvage eductors
Emergency cooling to main propulsion gas turbines/diesel generators
Auxiliary machinery cooling water system
Making of fresh water
Flushing heads(on some types of ship)
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5
Q

What are the salt water pumps

A

One pump must always be in use with the others in standby. Special operations may require more pumps to be running, such as flight deck operations.

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6
Q

Where are the Salt water pumps started from?

A

Can be started locally or remotely

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7
Q

What is a fixed spray and what areas will they be used in?

A 
A fixed fire fighting system that can be automatic or manually operated.
Used in areas such as:
Magazines
Paint lockers
Inflam store
Funnel
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8
Q

What is Pre-wetting?

A

Operated in an NBC environment to reduce contamination levels of the upper decks. Decks are sprayed and the ship moves side to side to wash off decks.

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9
Q

What is DC state 1?

A

Individual pumps supply their own section of the ringmain.

This ringmain is isolated by shutting the state valves to minimise effects from damage.

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10
Q

What is DC state 3?

A

All main isolating/ state valves are open.
One pump supplies the whole system.
A second pump can be started if pressure drops.
Suction is taken from the sea through a strainer.

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11
Q

What is used to cool engine coolant?

A

Sea water via a heat exchanger. Lubricants are cooled in the same way.

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12
Q

Reasons for fresh water circulating systems

A
  • Machinery is Susceptible to salt water corrosion

* Other equipment can be affected by salt water contamination e.g. Gas Turbine, Fuel systems and electric motors

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13
Q

Reasons for fresh water circulating systems

A
  • Machinery is Susceptible to salt water corrosion

* Other equipment can be affected by salt water contamination e.g. Gas Turbine, Fuel systems and electric motors

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14
Q

What will happen if you do not cool machinery correctly?

A

Fires
equipment failure
wiping of bearings
Equipment seizing

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15
Q

What temperature does white metal bearings melt at and what happens if you exceed the temperature?

A

115c, it will wipe the bearing.

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16
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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17
Q

How do we enable strainer cleaning?

A

a cross connection to the opposite side of the system can be opened to allow for strainer maintenance while the system continues to operate.

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18
Q

What machinery is supplied by the auxiliary circulation system?

A
  • Air Conditioning Plant

* Diesel Plant/Generators

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19
Q

Can the fresh water circulation system be cross connected to salt water in an emergency?

A

Yes with MEO permission.

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19
Q

Can the fresh water circulation system be cross connected to salt water in an emergency?

A

Yes with MEO permission.

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20
Q

What does MARPOL stand for?

A

Maritime pollution.
(It is your responsibility to know ship spill procedures)
(MEOOW must be informed of any MARPOL incidents)

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21
Q

What are the discharge of water regulations? (within 12 NM)

A
  • The oil content in the discharged water must not exceed 15ppm
  • The ship is underway with an oil content in the effluent under 15ppm
  • The ship has in operation an oily water separating filter with an oil discharge monitoring and control system
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22
Q

What are the discharge of water regulations (More than 12NM)

A
  • The oil content does not exceed 15ppm
  • The ship is underway with an oil content in the effluent under 15ppm
  • The ship has in operation an approved oil filtering system
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23
Q

What are the different special areas?

A
  • Baltic Sea
  • North West European Waters (including; North Sea, Irish Sea, Celtic Sea, English Channel, part of the North East Atlantic)
  • Mediterranean Sea
  • Black Sea
  • Gulf
  • Gulf of Aden
  • Caribbean
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24
Q

What are the four main sources of contamination?

A
  • Bilges
  • Fuel Systems
  • Oil Systems
  • CPP Systems (Controllable Pitch Propeller)
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25
Q

How do we minimise the risk of oil entering the bilge?

A
  • Keep machinery spotless – easier to identify leaks
  • Monitor Lube Oil ready use tanks and investigate any losses
  • No surfactants (Chemicals) to be used (“Kleen Break” only (Wet wipes))
  • AFFF only in real fire risk situations
  • Eductors to be manned when in operation
  • Maximise the use of shoreside facilities when alongside
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26
Q

Black water (Sewage)is defined as the drainage and waste from:

A
  • WC’s
  • Urinals
  • WC Scuppers
  • Medical compartments
  • Any water mixed with this waste
27
Q

What are the discharge regulations of black water?

A
  • Within 4NM discharge is only permitted with an IMO approved Sewage Treatment Plant (STP)
  • Between 4NM and 12NM discharge is only permitted if an IMO approved system to Comminute and disinfect the sewage is in operation
  • Over 12NM from shore no treatment is necessary
28
Q

Grey water is defined as the waste from:

A
  • Bathrooms
  • Galleys
  • Dishwashers
  • Laundries
  • Sinks
29
Q

What are the regulations of discharge of grey water?

A

There are no regulations concerning discharge at sea of grey water, only when entering/leaving port and when alongside.

30
Q

Why do we use a vacuum pumping system?

A

We use a vacuum pumping system because it has less moving/mechanical parts.

31
Q

What does the vacuum pumping system comprise of

A

A set of diesel or electric driven pumps

Manifolds and hoses (All black and grey water discharged an be collected and pumped to an available shore facility)

32
Q

What is the bilge?

A

spillage, leakage, condensation etc that accumulates at the bottom of the hull

33
Q

What is sullage?

A

= the left-over fluids/sludge after bilge water has been passed through a separator

34
Q

What do eductors do?

A

Eductors are used to remove quantities of fluid, generally oil/fuel/water, from the bilges very quickly.

35
Q

Role of the bilge system

A

Fitted to remove excess fluid from machinery space bilges to separate water from oil and discharge oil to sullage tanks using an oily water separator.
The water is discharged overboard.

36
Q

Role of the sullage system

A

Designed to retain dirty or waste oil/fuel until it can be properly discharged ashore.
Discharge from bilge system goes to sullage tanks or overboard when it does not contain oil/fuel.

37
Q

What does the HPSW pump and riser do?

A

HPSW pump supplies the ring main via the riser. The Riser has a 10% leak off to prevent over pressurisation.

38
Q

How do we operate an eductor?

A
  1. Open the discharge over board valve
  2. Open the motive water valve supplied from the HPSWM
  3. Open the bilge suction valves
    The motive force is salt water passing through a venturi in the eductor (Bernoulli’s Theorem)
    Only to be used with MEO permission.
39
Q

How do we operate an eductor?

A
  1. Open the discharge over board valve
  2. Open the motive water valve supplied from the HPSWM
  3. Open the bilge suction valves
    The motive force is salt water passing through a venturi in the eductor (Bernoulli’s Theorem)
    Only to be operated with MEO permission.
40
Q

What happens if the eductor system is operated incorrectly or the valves are opened in the wrong order?

A

The compartment will flood with sea water from HSWPM

41
Q

What are the health hazards from raw sewage?

A

Typhoid
Hepatitis
Gastro-enteritis

42
Q

What are the advantages of using a sewage treatment plant?

A
  • To reduce number of ship side openings
  • To simplify pipe runs
  • Heads and bathrooms can be lower in ship
  • Heads and bathrooms can be used in dry dock
  • The ship can operate in anti-pollution areas
  • It is easier to close down in CBRN conditions (and heads can still be used)
43
Q

Operation of a biological sewage treatment plant.

A

Raw sewage via macerator enters coarse screen-removes large particles.
Waste enters aeration compartment, aeration diffuser passes oxygen through waste.
Undigested waste sinks to bottom, digested floats-separating.
Air lift pump transfers waste to settlement hopper, heavy sludge sinks to bottom effluent floats on top.
Effluent weirs across to chlorine tank, weirs across again to collection tank.
Grey water added to dilute chlorine and disinfecting grey water- discharged overboard.
Sludge in hopper returned to aeration compartment via an air lift pump.

44
Q

What is aerobic digestion?

A

The action of digesting the sewage is known as “Aerobic Digestion” (the microorganisms thrive in air). We promote this by pumping air in.

45
Q

What is anaerobic digestion?

A

If the air supply fails the microorganisms will die, giving off a gas, Hydrogen Sulphide H2S, which smells like rotten eggs. This process is called “Anaerobic Digestion”.

46
Q

Collect and hold transfer system

A

A fully automated system whereby sewage is collected in tanks with a storage capacity of 12 days.
The sewage is collected by means of a vacuum.
Pumps draw vacuum from first tank which has a storage capacity of 1 day.
Tank is connected to WC.
Level switches ( A combined transfer/discharge pump) transfer the sewage to larger tanks where it remains until discharged.
An ejector circulates the sewage between tanks preventing it from becoming anaerobic digestion.
The vacuum pumping system transfers the sewage to shore when alongside.

47
Q

Rules on transferring sewage to shore.

A

If in port for less than 72 hours contractors will carry out the job.
More than 72 hours, the crew will carry out the work, team of 20 organised by ME department.

48
Q

What is a H2S monitor?

A

Monitors levels of H2S, must be turned on before entering compartment.

49
Q

What are the hazards of operating and maintaining an STP system?

A

Dangerous chemicals – eg calcium hypochlorite
Raw sewage – typhoid, hepatitis etc
Dangerous gasses – hydrogen sulphide (H2S) and methane

50
Q

Hazards of hydrogen sulphide(H2S)

A

70 – 150 ppm Kills sense of smell in about 3 – 15 mins, irritates eyes, throat and lungs
700-1000ppm IMMEDIATE THREAT TO LIFE rapidly produces unconsciousness, permanent brain damage is possible
Over 1000 ppm IMMEDIATE UNCONSCIOUSNESS AND DEATH WITHIN SECONDS

51
Q

Three main hazards while working onboard?

A

Chemicals
Raw sewage
Gasses

52
Q

What precautions do we take to prevent harm from chemicals, raw sewage and gasses?

A

Methane gas is flammable
Chlorine gas is harmful when inhaled
Medical protection- inoculations and medical staff to treat injury’s
Personal hygiene standards- wash your hands
PPE
Monitor atmosphere e.g. H2S monitor

53
Q

What are the advantages of compressed air?

A
  • Easily distributed throughout the ship
  • Can be easily stored
  • Flexibility and reliability of use
  • Low risk of fire
54
Q

What are the two categories of high pressure air?

A

HP air operating at 276 bar

HP air operating below 276 bar for a specific need

55
Q

What are the two areas of HP air?

A

IMS (inside machinery space)

OMS (outside machinery space)

56
Q

What is HP air used for?

A
  • Diesel engine starting
  • Gas turbine starting
  • Ship siren operation
  • Breathing apparatus (BA) charging
  • Weapon systems operation
  • Hydraulic system accumulator charging
  • Air driven machinery operation
  • Cross connection to Low Pressure Air System (276 bar to 8 bar)
57
Q

What are the four stages of the high pressure air compressor?

A

Stage 1 – 4 bar
Stage 2 – 17.5 bar
Stage 3 – 68 bar
Stage 4 - 276 bar

58
Q

Each stage has a pressure relief valve, what are the four pressure figures when the valves are applied?

A

1st PRV – 4.4 bar
2nd PRV – 19.25 bar
3rd PRV – 74.9 bar
4th PRV – 303.6 bar

59
Q

What are the four different alarms?

A

The Hamworthy- warns and stops high water temperature(54degrees c) and low oil pressure(0.69 bar).
Water Jacket Safety Valve: 3.5bar – protects the FW cooling system and SW main

60
Q

How is LP air created and supplied?

A

Its produced by either a Hydrovane or Rotary compressor, or supplied via a reducing station from the HP ring main. Operates at 8 bar.

61
Q

What is LP air used for?

A
  • Pneumatic Tools
  • Radar wave guides
  • Emergency Stern Seal inflation
  • Pneumatic Surveillance Panels
62
Q

What are the hazards and precautions when working on HP and LP air?

A

HP air can be lethal when directed at someone
Ear defenders must be worn
Explosions- Small amounts of oil/grease can explode when brought into contact with HP air, this is called dieseling. We use silicone grease is used to prevent this.
Hoses must be bound and tied to prevent flailing. They are lifed with an expiry date.

63
Q

What are the safe working practices when filling air bottles?

A
  • Bottle must be located in purpose built rack
  • Operators must be wearing PPE
  • Hoses must be in good condition and connected with the correct spanner
  • A good condition O Seal must be used
  • Bottle should be filled slowly to avoid overheating
64
Q

What PPE is required when charging air bottles from HP air?

A

Goggles

Ear defenders

65
Q

What is IMO?

A

International maritime organisation

66
Q

What is the HPSW ring main?

A

A ring of pipework running around 2 deck that can be subdivided by isolation valves.

ETICC (11 decks)

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