Theory 4 Flashcards
1
Q
describe the relationship between pressure and volume
A
as pressure increases, volume decreases or vice versa
2
Q
describe the relationship between boiling point and pressure
A
As pressure decreases boiling point decreases or vice versa
3
Q
what are 3 methods of heat transfer?
A
- convection
-conduction
-radiation
4
Q
how does heat travel?
A
hot —> cold
5
Q
what is it called when the temperature of a material increases but the state doesn’t change?
A
sensible heat
6
Q
what is it called when the temperature of a material stays the same but the state changes?
A
latent heat
7
Q
what is superheating?
A
substances temperature goes above its boiling point
8
Q
what is sub cooling?
A
cooling substances below its boiling point
9
Q
name the examples of the on-board refrigeration plants
A
- cold room
-cool room dairy
-fruit and veg store
-galley ready use cupboard
10
Q
what is the temperature range of the cold room?
A
-18 —> -22 degrees C
11
Q
what is the temperature range of the cool dairy room?
A
4 —>6 degrees C
12
Q
what is the temperature range of the fruit and veg store?
A
4 —>6 degrees C
13
Q
what is the temperature range of the galley ready to use cupboard?
A
5 —>7 degrees C
14
Q
what are the 4 components of the refrigeration cycle?
A
- compressor
- condenser
- thermal expansion valve (TEV)
- evaporator
15
Q
describe the compressor
A
- cool gas enters the compressor
- compresses the gas to form a high pressure, temperature gas
- provides the motive force in the cycle
16
Q
describe the condenser
A
- high pressure hot gas is condensed into a high pressure liquid
- sub-cooling is used to ensure all gas is converted to liquid
17
Q
describe the thermal expansion valve (TEV)
A
- slows the flow rate of the refrigerant
-lowers the pressure and temperature - TEV senses the temperature of refrigerant leaving the evaporator to control the flow of the refrigerant
18
Q
describe the evaporator
A
- evaporators the liquid to a gas
-superheats the refrigerant so no liquid enters the compressor
19
Q
what does the HP cut out do?
A
shuts down the plant if the pressure gets to high
20
Q
what does the oil separator do?
A
separates the oil from the refrigerant and directs the oil back to the compressor sump
21
Q
what does the liquid receiver do?
A
store’s refrigerant for maintenance
22
Q
what does the drier do?
A
removes any moisture from the refrigerant liquid
23
Q
what does the sight glass indicator do?
A
green indicates, its dry
yellow indicates its wet
24
Q
what are the 3 methods of defrosting?
A
- natural defrosting
- hot gas defrosting
- electric heating coil
25
how often do you defrost refrigeration plant using natdefrosting?
every 3-6 months
26
how often do you defrost refrigeration plants using hot gas defrosting?
4x15 mins per day
27
how often do you defrost refrigeration plants using electrical heating coil?
1 hour per day
28
what gases does the motels protocol aim to phase out of production and use of ?
- CFCs
-HCTCs
-halons
29
what gases does the Kyoto summit agreement aim to phase out production and use of?
-CO2
-HFCs
-PFCs
30
what are the methods of leak detection ?
- infrared leak detection system
-oil slicks
-spectrolyne dye and UV
- snoop
-halogen leak detector
31
what oils are commonly used in RN refrigeration plants?
- OM70
-SUNISO 3GS
-SW68
32
what does Hydroscopic mean?
readily absorbs moisture
33
why are open/damaged cans of oil to be discarded?
to avoid contamination with moisture from the air
34
how can oil be added to the sump in refrigeration plants?
- sump filter plug
-hand pump
-dosing pot
35
what does the chilled water plants provide cooling for?
- weapons systems
-radars
-ships computer systems
- air treatment unit
36
what is the difference between the chiller system and refrigeration system?
has a chiller instead of the evaporator
37
what is used to cool the condenser and motor?
sea water
38
what are refrigerant vapours dangerous?
displace the oxygen in the compartment as refrigerants tend to be heavier than oxygen so will sink to lower ares of the compartments
39
what gas is produced when refrigerants come into contact with heat?
Phosgene gas
(mustard gas)
40
what gas is produced when fruit and veg start to degrade?
CO2
41
what procedures need to be carried out before entering the refrigeration compartment?
- people are to be informed before entering the compartment
-breathing apparatus available
-high and low exhaust fans are running
- no smoking anywhere in the compartment
- ensure the infrared leak detection system is working correctly
- personal trapped warring lights are in working order
-ensure there is a sensory
-ensure the internal door opening mechanism is working correctly
42
what do you do if you get refrigerant in your eyes?
flush with water and report to medbay
43
what do you do if you get refrigerant on the skin?
wash off immediately and report to medbay
44
what equipment and uses require ventilation?
-cooling of electronic equipment
-CBRN
-habitability
-main machinery space cooling
- galley ventilation
45
what are the configurations of ventilation?
-fan supply and exhaust
-fan supply and natural exhaust
-natural supply and fan exhaust
-natural supply and natural exhaust
46
where and why is fan supply and fan exhaust used?
removes large quantities of air and provide fresh air for personnel working in the compartments
machinery space, galley, laundry, bathrooms
47
where and why is fan supply and natural exhaust used?
supply of fresh air is primary objective
store rooms and workshops
48
where and why is natural supply and fan exhaust used?
removable of noxious gases and flammable vapours is primary objective
paint shops, inflam stores, sprit rooms
49
where is is natural supply and natural exhaust used?
minor unoccupied compartments and lobbies
50
name the common filters
- lint filters
-panel filters
-dust filters
- supply fliters
-grease fliters
-flameproof gauzes
51
where are the special filters?
-galleys
-store rooms
-axillary machinery spaces
- magazines
-paint stores
52
which compartments have fire flaps built into exhaust trunking?
- galleys
-main machinery spaces
-magazines
53
what are the requirements of a ventilation system in an STP space?
- 15 air changes an hour
- low level exhaust system
- excess of exhaust capacity from that supply
54
what are the percentages of air used in the ATU's?
-33% fresh air
- 67% recirculated air
55
what do AFUs consist of?
- preparticulate filter --> paper filters that remove all course particles
- particulate filter --> fibre glass that removes Bactria
- gas filter --> charcoal removes all known chemical warfare
56
how does Citadel work?
- a whole ship chemical, biological and nuclear shelter
-by closing the ship down to an increased gas tight state
- increasing atmospheric pressure within the shipabove external pressures by using AFUs
57
when are Citadel tests carried out?
- annually
-prior to DED (Docking extended duration)
-During harbour acceptance trials (HATs)
-During sea acceptance trials (SATS)
- During FOST workup
58
what pressure is needed for the citadel to be effective?
2"WG
59
when does the air bleed valve lift?
when air pressure exceeds 1/2 "WG
60
when are AFUs used?
CBRNDC State 1 condition alpha zulu
61
when is the crash stop used?
when all fans needed to be stopped in case of an emergency e.g. fire/explosion
62
where is the crash stop operated from?
SSC/HQ1
63
when are the fans restarted?
when checked that they are clear of smoked and debris
64
what is the definition of a fluid?
- substance that will readily take the shape of its container
- capable of transmitting power
-liquid or gas
65
what are the advantages of hydraulics?
- reliable
-simple, easy to understand
-infinite speed range
- easily reversed
-ability to withstand overload
- no sparks risk
-high torque at low levels
- 1/12 size of equivalent electric motor
66
what are the disadvantages of hydraulics?
- fire risk with mineral oil systems
-noise
-risk of contamination
-less efficient (85-95%)
67
what does denso steel working mastic give off when ignited?
toxic gas
68
where is denso steel working mastic stored?
flammable store
69
when is denso steel mastic used?
upper deck for hydraulic fittings
70
what is in pipework sealing joints and what are they made of?
O-rings
made of flurocarbon elastomers
71
what dose fluorocarbon elastomers give off when heated above 300 degrees C?
toxic gases including hydrogen fluoride
72
what PPE is required when working with flurocarbon elastomers?
- PVS gauntlets
-rubber boots
-PVC coveralls
-full face visor
73
what are the overall health and safety risks when working with hydraulics?
- hydraulic fluid can cause skin irritation
- change oil soaked clothes immediately
-any skin irritation should be reported to medbay
-always consult hazard data sheet
-mineral oil is a fire hazard, leaks cleaned up immediately
-flexi hoses in date for test
-gauge glass valves to be shut when not in use
-suitable precautions to be taken before welding or burning in the vicinity
74
what are the 2 types of hydraulic fluid?
- petroleum based
-synthetic based
75
which oils are used in hydraulic systems?
- OM33
-OX40
-OX30
76
what colour is OX30?
Red
77
what colour is OM33?
Ornage/yellow
78
What colour is OX40?
Green
79
What are the requirements for hydraulic oil?
- be incompressible, transmit power effectively
- food lubrication properties
-good sealing properties
-give up heat readily
80
what does demulsibility mean?
the ability of a fluid to separate out from water
81
what are the most common types of oi contamination?
- airborne particles and moisture
-construction dirt
-dirt in new fluid
-dirt produced by wearing in new systems
- dirt from human sources
82
what methods are used to reduce contamination?
- good system design
- filtration and filter maintenance
- operation of filter and clogging indicators
- good working practices
-guardian filter pack
-caps should be fitted to open pipework
-clean working area
83
what components are in the anchor windless hydraulic system?
tankk
filters
relief valve
cooler
pressure gauges
valves
non return on discharge side
float switch
pump
control valve
actuator
84
what type of pump is used in the hydraulic system?
positive displacement
85
what types of positive displacement pumps are used?
- external gear pump
-internal gear pump
- vane pump
-lobe pump
-single piston pump
-multi piston pump
86
what does the control valve do?
controls oil flow and direction
87
what does an actuator do?
reverts hydraulic pressure into mechanical motion
88
what is the purpose of the drain leg?
to return cooling oil and sealing oil from the actuator to the tank
89
what is an acumulator?
a device in which potential energy is held and smooths out pulsations
90
what are two types of accumulators?
- bag
-piston
91
what are axial piston pumps used in?
- stabiliser systems
-CPP sytsems
- steering systems
92
what is fresh water used for?
- laundry
-galley
-shower and sinks
-water heaters
-medical use
-bridge window washers
-fresh water hose reals
- machinery cooling
- gas turbine washing
93
what is desalinated (made water)called?
permeate
94
what is waste water after desalination called?
concentrate
95
what does TDS stand for?
total dissolved solids
96
what is the TDS of sea water?
34,000ppm
97
what is the TDS of the permeate?
250-300ppm
98
how much of the supplied sea water is ejected overboard?
80%
99
what is the TDS of the ejected concentrate?
56,00ppm
100
what does the bag filter, filter down to?
60 microns
101
what does the cartridge filter, filter down to?
10 microns
102
what pumps is used in the reverse osmosis plant?
HP
3 piston
positive displacement pump
103
what pressure does the pump in the reserve osmosis plant operate at?
65 Bar
104
what does the concentration valve do?
- can be open or closed
-forcing more or less water through the membranes
- controls the TDS of the permeate
105
what anti-scalent is used in fresh water systems?
hyperspere
106
what are the chlorine levels in the fresh water tank maintained at?
0.2 ppm
107
who authorises/ supervises any addition of chlorine to fresh water tanks?
section head
108
when are chlorine levels tested?
daily and before embarkation
109
what colour are fresh water hoses?
blue
110
what needs to be done to fresh water hoses before they are used?
flush them
111
what are the tests carried out on fresh water?
- CHEMets test (chlorine)
-visual
-taste
112
how often do you carry out CHEMets test?
daily and before embarkation
113
how do you record the levels in the fresh water tank?
sounding tube
dip tape
conversion chart
114
how do you get hot fresh water onboard ship?
calorifier
115
what does the air eliminator do?
eliminates air and prevents water hammer
116
when are fresh water levels checked?
hourly
117
where are fresh water levels recorded?
SCC
