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Theory 4 > Theory 4 > Flashcards

Theory 4 Flashcards

1
Q

Explain pressure/volume relationship to boiling point

A

The higher the pressure, the higher the boiling point

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2
Q

Explain heat transfer

A

Heat always transfers from hot to cold, By three different methods:

  • conduction - direct contact
  • convection - moving hot air
  • radiation - direct heat source
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3
Q

explain latent heat

A

Refers to the temperature required to change the state of a substance

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4
Q

explain sensible heat

A

The heat applied to a substance whilst it still remains the same state

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5
Q

explain superheat

A

Maintaining a temperature above a substances boiling point (change of state)

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6
Q

explain the purpose of the compressor

A

To turn a low pressure gas into a high pressure gas

Pumps refrigerant around the system

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7
Q

explain the purpose of a condenser

A

To turn a high pressure gas into a high pressure liquid

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8
Q

explain the purpose of a TEV (thermal expansion valve)

A

Turns high pressure liquid into low pressure liquid

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9
Q

explain the purpose of an evaporator

A

Turns low pressure liquid into low pressure gas

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10
Q

What are hydraulic O-rings made from? What temp do they retain their elastic properties till? What happens if they burn

A

Made from fluorocarbon elastomers, retains properties until 300*c, after which they give of the toxic gas hydrogen fluoride

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11
Q

What are the two categories of hydraulic oil

A

Petroleum & synthetic based

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12
Q

What type of oil is used on submarines? No. & colour

A

Ox30 - red - synthetic

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13
Q

What type of oil is used on T23 & T45? No. & colour

A

Ox40 - green - synthetic

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14
Q

What type of oil is used on T22, T42 & CVS? No. & colour

A

Om33 - yellow/orange - petroleum

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15
Q

What are the desirable properties of hydrolic oil

A 
Transmission of power
Flow easily through lines
Practically incompressible 
Lubricating
Cooling
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16
Q

What does demulsibility mean

A

Fluids ability to separate from water

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17
Q

Why are anti oxidants added to oil

A

Reduces likelihood of sludge occluding in the oil

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18
Q

List hydraulic pumps

A 
External gear type pump
Internal gear type pump
Vane pump 
Lobe pump
Piston type pump (single)
Piston/plunger type pump (multi)
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19
Q

Explain axial piston pump operation

A

Cylinder 1, plunger at highest point, no axial movement, suction & delivery valves shut
C2, plunger on inlet stroke, suction valve just opening, delivery valve shut
C3, plunger nearing end of inlet, suction closing, delivery shut
C4, plunger starting delivery stroke, suction shut, delivery just opening
C5, plunger at maximum part of delivery stroke, suction shut, delivery fully open

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20
Q

What does an actuator do? What types are available?

A

Converts energy (system pressure) into mechanical motion, the types:

Linear; single & double acting
Rotary

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21
Q

What is the purpose of the return leg

A

Allows oil used for cooling/sealing the actuator/motor to return to tank

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22
Q

Advantages of hydrolic system over electric system

A 
Reliable
Simple to understand 
Infinite speed range 
Easily reversed
Ability to withstand overload
No spark risk
High torque at low speed
1/12 size of electric motor
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23
Q

Uses of ventilation

A 
Cooling electronic equipment
CBRN
Habitability
Machinery space cooling
Galley ventilation
24
Q

List the types of ventilation configurations, and where they’re used

A
  • Fan supply & fan exhaust- machinery space, galley, laundry, w.c.
  • Fan supply/natural exhaust- store rooms, workshop
  • Natural supply/fan exhaust- paint stores, inflam stores, spirit rooms
  • Natural supply/natural exhaust- minor unoccupied compartments & lobbies
25
Q

Types of filter

A
  • Panel filter- air con systems
  • Supply filter- air treatment unit (ATU)
  • Grease filter- galley
  • Lint filter- laundry
  • Dust filter- computer/sonar instrument spaces, sickbay
  • Flameproof gauzes- inflam stores, paint shop, magazine, hanger, vehicle deck
26
Q

What percentage of air is fresh/ recirculated

A

Fresh air 33% / Recirc air 67%

27
Q

Uses of fresh water onboard

A 
Laundry
Galley
Showers/sinks
Water heater
Medical use
Bridge window washers
Fresh water hose reels
Machinery cooling
Gas turbine washing
28
Q

Purpose of reverse osmosis

A

To remove molecules from a solution using a filter & pressure-Onboard this process is used to produce freshwater from seawater

29
Q

What is TDS & what’s it measuring

A

Total dissolved solids- measures salt in seawater (ppm)

30
Q

How much salt water is rejected

A

80%

31
Q

What type of filter is fitted to a reverse osmosis plant? What level do they filter to?

A

Pre-filter, down to 60 microns

32
Q

Explain the reverse osmosis pump

A

Positive displacement. High pressure pump, operates at 10-65 bar.
(In-line pulsation dampeners are fitted to smooth out suction pulsations)

33
Q

Explain the CCV’s (concentration control valve) function

A

Fitted to discharge lines to increase back pressure, ensuring saltwater is pushed through filter, allowing for reverse osmosis

34
Q

How is scaling prevented on RO membrane

A

Using an anti-scalant dosing unit (continuous chemical dosing)

35
Q

Explain alongside procedure for bringing aboard fresh water

A
  1. Get fresh water hoses & connections from store
  2. Unscrew deck cap to filling connection
  3. Fit filling gooseneck to filling connection
  4. Fit hoses to shore supply
  5. Open shore supply valve & flush hoses
  6. Conduct water tests
  7. Shut shore supply valve
  8. Fit hoses to deck filling gooseneck
  9. Dip & record tank levels
  10. Open tank filling valves
  11. open shore supply valves
  12. Open ships main fresh water isolating valve
  13. regularly check tank levels & test water
36
Q

What is chlorine limit in fresh water

A

0.2ppm

37
Q

How often is water checked for chlorine

A

Daily

38
Q

What tests are performed on fresh water

A

Visual, taste, CHEMest

39
Q

How often are fresh water levels checked/recorded

A

Daily ?

40
Q

How is water heated onboard

A

Calorifiers

41
Q

What is an ‘air hammer’ & how is it eliminated

A

A banging noise in pipes caused by trapped air. Can be eliminated with an air eliminator

42
Q

What’s the purpose of moisture indicating sight glass? What does it show?

A

Indicates moisture in refrigerant. Yellow indicates moisture, green indicates no water

43
Q

What’s the Montreal protocol agreement

A

Phase out harmful, ozone depleting substances/refrigerants, such as:
CFC
HCFC
Halons

44
Q

What’s the koyoto summit agreement

A

Reduce greenhouse gasses, such as:
CO2
HFC
PFC

45
Q

Methods for refrigerant leak detection

A 
Oil slicks
Infrared leak detection system       (IRLDS)
Sloop
Halogen leak detection 
Spectrolyne dye & UV lamp
46
Q

3 oils used in refrigeration system

A

OM70
SUNISO
3GS
SW68

47
Q

What does an oil being ‘hygroscopic’ mean

A

It readily absorbs moisture from the air

48
Q

From what source should oil be used

A

A sealed container

49
Q

What should happen to oil after use

A

Re-used (closed loop system)

Unused oil from container cannot be used and must be disposed of responsible

50
Q

How can oil be added to refrigeration system

A

Sump filler pump
Hand pump
Dosing pot

51
Q

When will phosgene gas be created

A

If CFC refrigerants are exposed to high heat source

52
Q

What is given off when fruit & veg decompose

A

Carbon dioxide CO2

53
Q

What is the procedure for entering refrigeration compartments

A 
No smoking/hot work
Inform rating in charge of watch
High & low exhaust fans are on
IRLDS work
Breathing apparatus work
Trapped warning lamps work
Accompanied by someone else
Doors work
54
Q

What should you do if refrigerant gets in your eye

A

Don’t rub, wash under running water, opening & closing eyes

55
Q

What systems are supplied with chilled water

A

Weapons systems
Radar
Ships computer systems
Air treatment units (ATU’s)

56
Q

What is the difference between refrigeration & chilled water system

A

Refrigeration units-
direct refrigeration, cools down room
Chilled water system-
cools water, which then circulates around the ship

57
Q

What provides cooling for the condenser & motors

A

Seawater cooling pump

Theory 4 (1 decks)

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