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Theory 4 > Refrigeration and ventilation > Flashcards

Refrigeration and ventilation Flashcards

1
Q

The main refrigeration plant comprises of:

A
  • Cold rooms and cool rooms
  • domestic refrigerators
  • ice making machines
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2
Q

How do you make water boil at a higher boiling point?

A

Increase the pressure on it

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3
Q

How do you lower the boiling point?

A

Decrease the pressure on it

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4
Q

What temperature does water boil at?

A

100 degrees

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5
Q

What are the three methods of heat transfer and describe each one

A
  1. Conduction - the transfer of heat between two solid bodies
  2. Convection - moving heat using air

3 . Radiation - the electromagnetic transfer of energy

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6
Q

What three forms can water exist in?

A

Solid (ice)
Liquid (water)
Gas (vapour)

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7
Q

What is sensible heat?

A

Temperature rises but no change of state

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8
Q

What is latent heat

A

No change in temperature but the state changes

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9
Q

What is superheat

A

The heat added above boiling point (100 degrees for water)

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10
Q

What is sub cooling

A

The removal of heat

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11
Q

What temp is the cold room

A

-18 to -22 degrees

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12
Q

What temp is the cool room

A

4 to 6 degrees

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13
Q

What temp is the fruit and veg store

A

4 to 6 degrees

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14
Q

What temp is the galley ready use cupboard

A

5 to 7 degrees

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15
Q

4 components of the refrigeration system in order

A

Compressor
Condenser
TEV
Evaporator

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16
Q

What does TEV stand for

A

Thermal expansion valve

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17
Q

How does the TEV work

A

Slows the flow rate of the refrigerant to lower the temperature and pressure

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18
Q

What does the HP cut out do

A

Protects the compressor if the discharge pressure gets too high

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19
Q

What does the oil separator do

A

Separates oil from the refrigerant

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20
Q

What does the liquid receiver do

A

Provides a liquid seal between the condenser and the TEV

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21
Q

What does the liquid line stop valve do

A

Shutting the valve prevent refrigerant leaving the liquid receiver

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22
Q

What does the drier do

A

Removes moisture

23
Q

What colour means what on the sight glass indicator

A

Green - indicates dry
Yellow - indicates moisture

24
Q

What does the LP cut out do

A

Stops the compressor if pressure gets too low on the suction side

25
Q

What is the Montreal protocol 1987

A

An arrangement to phase out the use of all harmful CFC gases

26
Q

3 ozone depleting substances

A
  • CFC
  • HCFC
  • HALONS
27
Q

What is the Kyoto summit

A

Reduce greenhouse gases

28
Q

Methods of leak detection

A
  • infra red leak detection system (IRLDS)
  • oil slicks
  • spectrolyne dye and UV lamp
  • snoop
  • halogen leak detector (very sensitive)
29
Q

What needs lubrication

A

The compressor

30
Q

3 lubricants

A
  • OM70
  • SUNSIGO 3GS
  • SW68
31
Q

What does hygroscopic mean

A

Absorbs moisture

32
Q

How big are the cans of oil and what is the rule?

A

500ml to 5ltr
Only use the smallest can required

33
Q

How can oil be added to the sump

A
  • sump filler plug
  • hand pump
  • dosing pot
34
Q

What do chilled water plants provide cooling for

A
  • weapons systems
  • radars
  • ships computer system
  • air treatment units (ATU)
35
Q

What is a chilled water plant called

A

Chiller

36
Q

What temp does the chilled water leave and return at

A

Leaves at 4-6 degrees
Returns at 13-20 degrees

37
Q

How is phosgene gas (mustard gas) produced

A

If CFC refrigerant come into contact with a high heat source

38
Q

What procedures must you carry out before entering the refrigeration machinery room?

A
  • someone knows where you are
  • breathing apparatus is available
  • fans are running
  • no smoking
  • IRLDS is working
  • warning lights are working
  • you have a sentry
  • the door mechanism works
39
Q

Uses of a ventilation system

A
  • cooling of electronic equipment
  • CBRN
  • Habitability
  • main machinery space cooling
  • galley ventilation
40
Q

What are the four combinations of supply and exhaust ventilation and where are they used

A
  1. Fan supply and fan exhaust - used in machinery spaces, galleys laundries, WCs and bathrooms
  2. Fan supply and natural exhaust- used in store room and workshops
  3. Natural supply and fan exhaust- used in paint stores, spirit rooms and Inflam stores
  4. Natural supply and natural exhaust- used in minor unoccupied compartments and lobbies
41
Q

6 Types of filters

A
  • panel filters
  • supply filters
  • grease filters
  • lint filters
  • dust filters
  • flameproof gauzes
42
Q

What compartments require special filters

A

Galley
Store room
Auxiliary machinery spaces
Magazines
Paint stores

43
Q

What compartments have fire flaps

A

Galleys
Main machinery spaces
Magazines

44
Q

What areas need special requirements

A
  • Galleys
  • Store rooms
  • Auxiliary machinery spaces
  • Sewage treatment spaces (require 15 changes per hour)
  • magazines (fitted with there own air conditioning which allows 100% treated fresh air)
45
Q

The AFU consists of 3 sections which are:

A
  • pre particulate filter (paper filter removed coarse particles)
  • particulate filter (made of glass givers to remove bacteria)
  • gas filter (removes chemical)
46
Q

when are citadel tests carried out

A
  • annually
  • prior to DED (dicking extended duration)
  • during harbour acceptance trials
  • during sea acceptance trials
  • during a FOST work up
47
Q

how is a citadel test conducted

A
  1. Close all openings on the Citadel boundary and put system on re-circ
  2. Open AFU inlets and start AFUs
  3. Restrict access to and from Citadel to essential personnel only. AIRLOCKS MUST BE USED.
  4. Search for leaks and carry out temporary repairs.
  5. Record the result of the test in the SEF & D171 Part II survey report
48
Q

where is the crash stop board

A

SCC/HQ1

49
Q

what is the crash stop

A

built into the ventilation system to allow fans to be stopped in case of an emergency

50
Q

whats Michael Dents middle name?

A

John William

51
Q

What is natural defrosting and when is it done

A

Turn the fridge off and it’s carried out every 3-6 months or when the ship will de-store

52
Q

What is hot gas defrosting and when is it carried out

A

Uses hot high pressure vapour which is passed through the evaporator. Carried out for 4 15 minute sessions throughout the day

53
Q

How do you defrost using electrical heating coils and when is it done

A

Uses either rod type or wrap around coils in the evaporator. Carried out for a maximum of 1 hour (to prevent the oil from burning)

Theory 4 (3 decks)

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