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RN - ETME > Mechanical Theory 4 > Flashcards

Mechanical Theory 4 Flashcards

1
Q

explain the pressure/volume relationship

A
  • Low pressure – volume increase – less energy required
  • High pressure – volume decreases – more energy required
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2
Q

briefly explain heat transfer

A
  • Conduction – direct contact through solid
  • Radiation – energy transfer through air
  • Convection – energy transferred through fluid
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3
Q

breifly explain latent heat

A

temperature stays the same but the state changes

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4
Q

briefly explain sensible heat

A

increase of temp but state stays the same

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5
Q

briefly explain super heat

A

any temperature above the boiling point

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6
Q

explain the purpose of the compressor

A
  • Raises the pressure of refrigerant
  • (no liquid should enter the compressor – liquids cannot be compressed)
  • Refrigerant leaving the compressor is a high-pressure hot gas
  • Motive force
  • Positive displacement pump
  • Quadrant 1 – high pressure, hot gas
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7
Q

explain the purpose of the condenser

A
  • Condenses the hot gas into a warm, high pressure liquid
  • Must be a liquid on leaving the condenser
  • Use sea water as a cooling medium
  • Quadrant 2 – high pressure, warm liquid
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8
Q

explain the purpose of the evaporator

A
  • Cold liquid refrigerant enters the evaporator
  • Leaves as a gas
  • Quadrant 4 – low pressure, cool gas
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9
Q

explain the purpose of the thermal expansion valve

A
  • rate of flow – can increase/decrease
  • Lowers the pressure
  • Still stays as a fluid
  • Thermometer – sense temp in refrigeration room – controls the rate of flow, to increase / decrease temp
  • Quadrant 3 – low pressure, very cold liquid
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10
Q

what is the purpose of the moisture indicating sight glass

A
  • Visible indication of refrigerant flow / shows presence of any moisture
  • Green – indicates dry
  • Yellow – indicates moisture
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11
Q

explain the montreal protocol agreement

A

Bunch of countries come together to control where refrigerants can be released

  • CFC
  • HCFC
  • HALONS
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12
Q

explain the kyoto summit agreement

A

Reduce and limit greenhouse gases
* CO2
* HFC
* PFC

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13
Q

state five methods refrigeration leak detection

A
  • Infra red leak detection system (IRLDS)
  • Oil slicks
  • Spectrolyne and UV lamp
  • Snoop
  • Halogen leak detector
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14
Q

state 3 oils used in a refrigeration system

A
  • OM- 70
  • SUNISO 3GS
  • SW68
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15
Q

from what source should oil be used

A

fresh unopened

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16
Q

what should happen to oil after use

A

how can oil be added to a refrigeration system

17
Q

what systems are supplied with chilled water

A
  • weapon systems
  • radar
  • ships computer systems
  • air treatment units
18
Q

what is the main difference betwen refrigeration and chilled water system

A
19
Q

what provides cooling for the condenser and motors

A

sea water
the system has its own, seperate sea water pumps

20
Q

when will phosgene gas be created

A

produced if the refrigerant comes into contact with heat
mustard gas - it is toxic

21
Q

what is given off if fruit & veg decomposes

A

as they degrade CO2 is produced
displaced oxygen in the air

22
Q

what is the procedure for entering a refrigeration compartment

A

*duty of the watch is to be informed that personnel are entering the compartment, & informed when the compartment is vacated.
* Breathing Apparatus is available
* high and low exhaust fans are running.
* No smoking. hot work is to be very closely controlled.
* Infra Red Leak Detections System (IRLDS) is working correctly & indicating safe.
* personnel trapped warning lamps are working

23
Q

what should you do if you get refrigerant in your eyes

A

flush with running clean water, then after seek medical attention

24
Q

state 5 uses of ventilation

A
  • Cooling of electronic equipment
  • CBRN
  • Habitability
  • Main machinery space cooling
  • Galley ventilation
25
Q

explain the 4 methods of ventilation configuration

A

Fan supply and fan exhaust
* removes large quantities of wild heat, moisture fumes coupled with the requirements to provide fresh air to personal working
* Machinery spaces, galley’s, laundries, W.C
Fan supply and natural exhaust
* Supply of fresh air to compartments is the primary objective
* Store rooms and workshops
Natural supply and fan exhaust
* Removal of noxious gases and flammable vapours is the primary object
* Paint stores, spirit rooms, inflame store
Natural supply and natural exhaust (barely used)
* Only used in minor unoccupied compartments and lobbies

26
Q

state 6 types of filter

A
  • panel filter
  • supply filter
  • grease filter
  • lint filter
  • dust filter
  • flameproof gauzes
27
Q

state 5 spaces that require special filters

A
  • Galleys
  • Store rooms
  • Auxiliary machinery spaces
  • Sewage treatment spaces
  • Magazines
28
Q

explain the requirements of a vent system in a STP space

A
  • 15 air changes in 1 hr
  • Low level exhaust
  • More exhaust than supply
29
Q

which compartments would require fire flaps

A
  • Galley
  • Main machinery spaces
  • Magazines
30
Q

what percentage of air is Fresh / re-circulated

A

fresh- 33%
re-circulated - 67%

31
Q

what NBCD state would AFU be used

A

state 1 - zulu alpha

32
Q

explain 3 types of filter found in a AFU

A
  • Pre-particulate filter - paper filter – removes coarse particulates
  • Particulate filter – glass fibre – remove particulates such as bacteria by entrapment
  • Gas filter – activated charcoal filling - remove all known chemical warfare agents
33
Q

what is the citadel

A
  • Whole ship chemical, biological and nuclear shelter
  • Formed by closing the ship down to an increased gas tight state
  • Works by increasing the atmospheric pressure within the ship above external using air filtered by AFU
34
Q

when would the citadel be tested

A
  • Annually
  • Prior to DED (docking extended duration)
  • During harbour acceptance trials (HATS)
  • During sea acceptance trials (SATS)
35
Q

when would an air Bleed valve operate

A
36
Q

where would a crash stop board be situated

A

SCC/HQ1

37
Q

when would the fans be restarted after a crash stop

A
38
Q

when would a crash stop be used

A

in the event of a fire, crash on deck

RN - ETME (7 decks)

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