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Air Diving Supervisors QUESTIONS > Air Physics > Flashcards

Air Physics Flashcards

1
Q

What’s the absolute pressure at depth of 254m?

A

26,4 bar

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2
Q

What’s the absolute pressure at depth of 254fsw?

A

254/33= 7,69+1= 8,69ATA.

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3
Q
  1. A diver is working at 100 fsw for 30 minutes. What volume of gas will he use?
A

100/33 +1 = 4.03
Diver cons = 1,25 cfm
Time = 30min
4,03x1,25x30= 151,2 ft3

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4
Q

A diver is working at 120 msw for 4 hours. What volume of gas will he use?

A

120m= 13bar
Diver consumption = 35l/m
4 hours= 240min

13x35x240= 109.200 litres = 109.2m3

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5
Q
  1. Two divers are working out of the bell at 75 msw. What volume of gas will they use in 4 hours?
A

8,5x35x240 x 2 divers = 142.8m3

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6
Q
  1. An air diver is working at 60 fsw for 20 minutes. What volume of air will he use?
A

60/33+1 = 2,82 x 1,25 x 20= 70,45 ft3

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7
Q
  1. A 64 x 50 litre quad contains gas at a pressure of 100 bar. What is the total volume of gas in the quad?
  2. The quad in Question 7 will be changed over when the pressure falls to 40 bar. What volume of gas is available to the diver?
  3. In Question 8, the diver is working at 130 msw. How long can he work for before the quad is changed over?
A

64x50x100= 320m3

64x50x60= 192m3

130m = 14 bar
Diver cons= 35l/m
Total gas 192.000

14x35= 490l/m
192.000/490 = 391,83min / 60 = 6h 32min
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8
Q

A diver is working at 80 msw, breathing from a 16 x 50 litre quad at a pressure of 150 bar. How long could he work for? (Assume that the quad will be changed over at 40 bar.)

A

Total gas = 16x50x110= 88.000litres
80m = 9 bar x 35l/m = 315lm
88.000/315= 279,36 =

4h39min.

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9
Q

A 64 x 50 litre quad is at a pressure of 205 bar. It can be used until the pressure falls to 30 bar. How much gas is available for use?

A

205-30=175bar

64x50x175= 560m3

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10
Q

A 12 x 50 litre quad is at a pressure of 25 bar. What volume of gas will be needed to fill it to a pressure of 200 bar?

A

200-25=175bar

12x50x175= 105m3

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11
Q
  1. A bail-out bottle has a volume of 12 litres and contains gas at a pressure of 200 bar. If the diver is working at 100 msw, what volume of gas is available to him in an emergency?
A

200-10-11=179bar x 12 = 2148l or 2.15m3

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12
Q

A diver is working at 195 msw, breathing from a 16 x 50 litre quad at a pressure of 110 bar. The quad will be changed over at 40 bar. How long could he work for?

A

110-40=70bar
70x16x50= 56.000l
20,5x35= 717,5lm

56000/717,5= 1h18min

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13
Q

A bailout bottle has a FV of 6 litres charged to 190 bar, how long it last a diver at depth of 48 msw ? (Assume 15 bar losses)

a) 6min
b) 4.5min
c) 3min
d) 7min

A

b) 4.5min

190-15=175 x 6 = 1050 litres
5.8 x 40 = 232 lm
1050/232 = 4.5min

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14
Q
  1. How much gas would a diver consume in 80 min at depth of 42 msw?
    a) 13.44m3
    b) 11.76 m3
    c) 145.6 m3
    d) 14.56 m3
A

d) 14.56 m3

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15
Q
  1. What’s the apparent weight in the seawater, of a 1000 m3 pontoon that weights 1500 tonnes in air?
    a) 470 tonnes
    b) 500 tonnes
    c) 1470 tonnes
    d) 1030 tonnes
A

a) 470 tonnes

1000 x 1.03 = 1030
1500 - 1030 = 470 tonnes

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16
Q

1ft3 of sea water weights?

a) 1000kg
b) 62.5 lbs
c) 64.38 lbs
d) 1030 kg

A

c) 64.38 lbs - seawater

Remember : 62.5 lbs is fresh water

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17
Q
  1. What’s the PO2 in breathing air @ 43 msw?
    a) 1.113 ba
    b) 0.903 ba
    c) 0.693 ba
    d) 0.483 ba
A

a) 1.113 ba

5. 3 x 0.21 = 1.113 ba

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18
Q
  1. What the PO2 in breathing air at 97 fsw?
    a) 1.025 ata
    b) 0.827 ata
    c) 0.609 ata
    d) 0.468 ata
A

b) 0.827 ata

97/33 + 1 = 3.939 x 0.21 = 0.827

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19
Q
  1. What’s the PO2 of 32% nitrox breathed at 27 msw?
    a) 1.184 ba
    b) 1.458 ba
    c) 0.119 ba
    d) 0.109 ba
A

a) 1.184 ba

3. 7 x 0.32 = 1.184

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20
Q
  1. You require a PO2 of 1.4 ba @ 38 msw, what’s the suitable nitrox mix?
    a) 38/62
    b) 40/60
    c) 50/50
    d) 28/72
A

d) 28/72

1. 4/4.8 = 0.291 x 100 = 29% O2

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21
Q
  1. What’s the maximum depth a diver could breathe 50/50 mixture with PO2 of 1.4 ba?
    a) 12 msw
    b) 1.8 msw
    c) 18 msw
    d) 15 msw
A

c) 18 msw

1. 4/0.5 = 2.8 bar = 18 msw

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22
Q
  1. What’s the maximum depth for breathing pure O2 when PO2 is 2.8 ba?
    a) 12 msw
    b) 1.8 msw
    c) 18 msw
    d) 15 msw
A

c) 18 msw

2. 8/1= 2.8 bar = 18 msw

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23
Q
  1. At what depth would air equal IMCA wet maximum PPO2?
    a) 67 msw
    b) 57 msw
    c) 50 msw
    d) 30 msw
A

b) 57 msw or 185 fsw

  1. 4/0.21=6.66-1x10= 56.66
  2. 66 x 3.28 = 185 fsw
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24
Q
  1. If a diver has 1 litre of gas in solution in his body at 1b, how much of the same gas would he have in solution at 50 msw after 10-12h?
    a) 5 litres
    b) 1 litre
    c) 6 litres
    d) 2 litres
A

c) 6 litres

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25
Q
  1. What is the apparent weight in seawater of a 1000 m3 pontoon that weighs 1500 tonnes in air?

1) 500 tonnes.
2) 1470 tonnes.
3) 470 tonnes.
4) 1030 tonnes.

A

3) 470 tonnes.

It’s in seawater remember, which is 1.03 tonnes per m3.
1000 x 1.03 = 1030 tonnes up thrust.
Weight of object in air minus the up thrust,
1500 - 1030 = 470 tonnes.

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26
Q
  1. A sunken pontoon 10m x 5m x 2m lies on a hard seabed and has an apparent weight of 4 tonnes, you de-ballast a compartment 2m x 2m x1m, what will happen?

1) It will be neutrally buoyant.
2) Nothing.
3) The apparent weight will be 8.12 tonnes.
4) It will raise to the surface.

A

4) It will raise to the surface.

2 x 2 x 1 = 4m3 of salt water up thrust which is 4.12 tonnes,
the object weighs only 4 tonnes in air so it will have a positive up thrust of .12 tonnes.

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27
Q
  1. An object has a density of 168 lbs / ft3 and is 50 feet long, 10 feet high and 8 feet wide. How heavy is it?
  2. An object has an area of 50 feet long, 10 feet high and 8 feet wide, what would be the up thrust in salt water? (Question before)
A

It weighs 300 tonnes.

50 x 10 x 8 = 4000 ft3
4000 x 168 lbs/ft3 = 672000 lbs
672000 / 2240 (tonne) = 300 tonnes.

It’s up thrust would be 257,520 lbs or 114.9 tonnes.

50 x 10 x 8 = 4000,
4000 x 64.38 lbs (ft3 of seawater) = 257,520 lbs
257,520 / 2240 (tonnes) = 114.9 tonnes.

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28
Q
  1. An object has an area of 50 feet long, 10 feet high and 8 feet wide, what the object appear to weight in salt water?
    Density of 168ft/lbs

a) 185 tons
b) 288 tons
c) 3808 tons
d) 38.8 tons

A

a) 185 tons

50 X 10 X 8 = 4000 X 64.38 = 672000/2240 = 300tons
Weight of the object 300 tons

4000 X 64.38 = 257520/2240= 114.9tons
Upthrust 114.9 tons

300-114.9= 185 tons

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29
Q
  1. If an object 15m long x 4m wide x 3m high had a density of 3800 kg/m3, what would it appear to weigh in fresh water?
    a) 860 tonnes
    b) 684 tonnes
    c) 86 tonnes
    d) 504 tonnes
A

D. It would appear to weigh 504 tonnes.

15m x 4m x 3m = 180m3
3800 / 1000 = 3.8 tonnes x 180 = 684 tonnes.
684 tonnes - 180 tonnes (up thrust of object in fresh water) = 504 tonnes.

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30
Q
  1. 1) If an object 15m long x 4m wide x 3m high, floats in seawater with 1m submerged, what must the density be?

2) Also how much more weight could be placed on the object before it sank?
3) If equipment weighing 18.26 tonnes were loaded on to part one of the question, how much of the pontoon would be under water?

A

1) Its density is 343 kg/m3
15m x 4m x 3m = 180m3, only 1 meter is submerged,
so the object must weight the same as 15m x 4m x 1m = 61.8 tonnes seawater up thrust,
Divide up thrust by the whole volume to find it density, 61800kg / 180m3 = 343 kg/m3.

2) 123.7 tonnes.
61.8 tonnes per 1 meter high, the object is three meters high
so x 2 more loads of 61.8 tonnes (123.6 tonnes will make the object neutral)
So 123.7 tonnes will give the object negative buoyancy.

3) 1.29m underwater in total.
18.26 / 1.03 (seawater) = 17.72
17.72 / 60 (area of object) = 0.29
So the object would sink a further 0.29 meters,
which in total would be 1.29 meters underwater.

Remember : D=volume submerged x 1.03/ total volume

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31
Q
  1. A bell weighs 8 tonnes and displaces 300 ft3 of seawater. How much weight must be added to make it sink?

a) 0.63 tons
b) 0.53 tons
c) 57 lbs
d) 128 lbs

A

a) 0.63 tonnes would need to be added to make it sink.

300 x 64.38 lbs = 19,314 lbs / 2240 (tonne) = 8.622 tonnes
Bell weighs 8 tonnes with 8.622 tonnes up thrust,
So you would need 0.63 tonnes more weight to sink it.

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32
Q
  1. A twin set is filled to 200 bar in a surface temperature of 39°C, underwater it cools to 4°C, what is its new pressure?
    a) 170 bar
    b) 177 bar
    c) 183 bar
    d) 194 bar
A

It’s new pressure is 177 bar.

39°C + 273 (kelvin) = 312
4°C + 273 (kelvin) = 277
200 / 312 = 0.64
0.64 x 277 = 177 bar.

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33
Q
  1. A bailout bottle has a pressure of 2640 psi at 41°F, what was its filling pressure at 70°F?
A

Its original pressure was 2793 psi at filling.

41 + 460 (Rankin) = 501.
70 + 460 (Rankin) = 530.
So 2640 / 501 = 5.2694 x 530 = 2793 psi.

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34
Q
  1. A quad at a pressure of 198 bar at 27°C cools to 17°C, what will the new pressure be?
A

It’s new pressure will be 191.4 bar

27 + 273 (Kelvin) = 300.
17 + 273 (Kelvin) = 290.
So 198 / 300 = .66 x 290 = 191.4 bar.

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35
Q
  1. A pressurised chamber contains 92 m3 of gas at 68msw, if it cools from 31°C to 28°C, what will be the new depth?
A

It’s new depth will be 67.1 msw.

31 + 273 (Kelvin) = 304.
28 + 273 (Kelvin) = 301.
So 68 / 304 = .223 x 301 = 67.1 msw.

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36
Q
  1. An air reservoir has a MWP (max working pressure) of 200 psi, if it is at 180 psi, with a temperature of 16°C and stands in the sunshine until the temperature reaches 28°C, what will the new pressure become?
A

It’s new pressure will become 187.4 psi.

16 + 273 (Kelvin) = 289.
28 + 273 (Kelvin) = 301.
So 180 / 289 = .6228 x 301 = 187.4 psi.

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37
Q
  1. An object 11m x 7m x 7m in the seabed, weight 600t.
    If pumped 50m3 of air. What will happen with the object?

IMCA EXAME!!!!!!

A

11x7x7 = 539 x 1.03 = 555.17t
600 - 555.17 = 44.83 t ( negative buoyant)

50 x 1.03 = 51.5 ton

ENOUGH TO BRING TO SURFACE POSITIVE BUOYANCY.

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38
Q
  1. A pontoon 12m x 7m x 3m floats with 2.5m submerged in seawater?
    a) what’s the upthrust?
    b) what’s the weight of the pontoon
    c) how much weight could I place on the deck without it sinking?
A

a) 12 x 7 x 2.5 = 210 x 1.03 = 216.3 tonnes upthrust
b) as it floats the pontoon weights is equal to the up thrust

c) 12 x 7 x 3 = 252 x 1.03 = 259.56
259.56 - 216.3 = 43.26 tonnes
Or
12 x 7 x 0.5 x 1.03 = 43.26 tonnes

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39
Q 
What is the pressure exerted at 1 atmosphere (Sea Level) ?
a 14.7 psi 
b 14.5 psi
c 0.445 psi
d 29.2 psi
A

a

14.5 is gauge

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40
Q 
Convert 6220 ppm to a %:
a 0.0622%
b 6.220%
c 0.622% 
d 0.0062%
A

c

Ppm to % = divide by 10.000
% to ppm = times 10.000
Ppm to bar = move back 6 spaces

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41
Q 
What is the absolute pressure exerted at a depth of 165 fsw?
a 8.82 psi
b 88.2 psi 
c 73.5 psi
d 165 psi
A

b

165 +33 = 198/33 = 6x14.7 = 88.2

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42
Q 
To convert degrees Celsius to absolute temperature you must add:
a 273 
b 460
c 32
d 100
A

a

+ 273 for celsius
+ 460 for kelvin

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43
Q 
What is 32ºC expressed in FAHRENHEIT?
a 305ºF
b 57.6ºF
c 89.6ºF 
d 92.4ºF
A

c

32x1.8+32 = 89.6

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44
Q 
How much gas does a 10 litre flask, charged to 200 bar hold?
a 2000 l 
b 200 l
c 10 l
d 2200 l
A

a

10x200= 2000l

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45
Q 
Convert 1.000 litres into cubic metres:
a 2 m3
b 1 m3 
c 1.2 m3
d 28.32 m3
A

b

1000l = 1m3

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46
Q

How much gas would be required to pressurise a chamber with a floodable volume of 28 m3 to a depth of 37 msw?

a 131.6 m3
b 1036 m3
c 103.6 m3
d 75.6 m3

A

c

3.7 absolute pressure x 28 = 103.6

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47
Q

A diver consumes 1.25 ft3/min at surface. How much gas would he require at depth of 100 fsw?

a 4.03 ft3
b 1.25 ft3
c 5.037 ft3
d 7.2 ft3

A

c

100+33/33=4.03 absolute pressure x 1.25= 5.037ft3

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48
Q

A compressor has a delivery of 7 ft3/min. To what depth would this support a
diver if his consumption is 1.25 ft3/min?
a 184.8 fsw
b 151.8 msw
c 151.8 fsw
d 51.8 fsw

A

c

7/1.25= 5.6 x 33= 184.8 -33 = 151.8fsw

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49
Q

A bail out bottle has a FV of 12 litres and is charged to 200 bar. How much gas is available to the diver at a depth of 42 msw? (Hat working pressure = 8 bar)

a 2400 l
b 2285.7 l
c 2253.6 l
d 2241.6 l

A

d

FV = 200-8-5.2= 186.8x12= 2.241.6l

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50
Q

A bank has 45 bottles, each have a FV of 50 litres. How much gas does it contain at a pressure of 185 Bar?

a 592 m3
b 450.2m3
c 416.25 m3
d 416.2 ft3

A

c

45x50x185= 416.250m3

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51
Q

A bailout bottle has a FV of 6 litres and is charged to 200 bar. How long would
it last a diver at a depth of 52 msw? (Use 40 l/min and 8 bar regulator pressure)
a 5 min 40 sec
b 4 min 30 sec
c 4 min 52 sec
d 4 min 41 sec

A 
b
200-8-6.2= 185.8 x 6 = 1.114.8/248= 4.49min
6.2x40= 248
49x60=29sec
4m29sec
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52
Q 
What is the pO2 at 47 msw if the breathing gas is air?
a 0.37 bar
b 1.2 bar 
c 0.99 bar
d 0.21 bar
A

b

5.7x.21= 1.19

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53
Q 
What is the partial pressure of Nitrogen in Air at a depth of 99 fsw?
a 3.16 ATA 
b 2.16 ATA
c 4.16 ATA
d 0.79 ATA
A

a

99+33/33=4x .79= 3.16

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54
Q

If a diver has 1 litre of gas in solution in his body at Sea level, how much of the same gas would he have in solution at 50 msw?

a 5 litres
b 1 litre
c 6 litres
d 2 litres

A

c

50m 6 bar

Charles law

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55
Q

A diver weighs 300 lbs and displaces 4.5 ft3 of salt water. If he wanted to be 20lbs negative, how much extra weight would he require?

a 7 lbs
b 9.7 lbs
c 7.9 lbs
d 17.9 lbs

A

b

4.5x64.38= 289.71 + 20= 309.71 - 300 = 9.71lbs

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56
Q

A container measures 10 x 3 x 4 m, it draws 2 m draft. What is the upthrust.received?

a 60 t
b 68 t
c 61.8 t
d 16.8 t

A

c

10x3x2=60x 1.03= 61.8t ( If sea water )

10x3x2= 60x1 = 60t ( if fresh water)

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57
Q

A diving bell receives an upthrust of 14,250 lbs and weighs 6.5 ton. How much buoyancy is required to make it 500 lbs positive?

a 500 lbs
b 710 lbs
c 810 lbs
d 760 lbs

A

c

6.5x2240 = 14560 - 14250= 310 + 500= 810

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58
Q

During blowdown to a depth of 100 msw a chamber reached a temperature of 35ºC. What would be the reading by gauge after cooling to 25ºC?

a 96.75 msw
b 96.43 msw
c 106.75 msw
d 106.43 msw

A

b

11/35+273 = 0.3571x298= 10.64 -1x10= 96.428

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59
Q

During pressurisation a bottle reached a temp of 40ºC. If the start pressure was
195 bar, what would the pressure be, after cooling to 20ºC?
a 204.3 bar
b 190.2 bar
c 182.5 bar
d 179.4 bar

A

c

195/40+273=0.623x293= 182.53

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60
Q 
What is the amount of gas required to blow down a chamber from 30 to 68 msw
if the FV = 14 m3?
a 53.2 m3 
b 109.2 m3
c 67.2 m3
d 91.2 m3
A

a

3.8x14=53.2m3

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61
Q 
How much gas would a diver consume over 4 hours at a depth of 110 msw if the
consumption rate was 35 l/min?
a 8.4 m3
b 100.8 m3 
c 92.4 m3
d 25.2 m3
A

b

12x35x240= 100.8m3

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62
Q 
Convert 0.37% into parts per million.
a 37 ppm
b 3700 ppm 
c 370 ppm
d 2700 ppm
A

b

.37x10000=3700ppm

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63
Q

1 bar is equivalent to:

a. 760 mm Hg - FOR EXAM PURPOSES
b. 750 mm Hg
c. 770 mm Hg
d. 740 mm Hg

A

b

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64
Q

6 bar gauge is equivalent to:

a. 165 fsw
b. 175 fsw
c. 198 fsw
d. 231 fsw

A

c

6x33= 198fsw

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65
Q

A diver suffering from decompression sickness is to be given a total of 6 cycles of 25 minutes each. The consumption rate is 40 litres per minute at surface. Chamber depth is 70 msw. How much gas will be used?

a. 4.8 m3
b. 48 m3
c. 480 m3
d. 42 m3

A

b

8x40x25x6= 48m3

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66
Q

A DDC with an FV of 25 m3 is pressurised to 80 msw. The temperature on arriving at 80 msw is 35°C. When the temperature fall to 30°C what was the depth of the DDC?

a. 78.7 msw
b. 92.5 msw
c. 82.6 msw
d. 78.5 msw

A

a

80 x 303 / 308 = 78.7m

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67
Q

A liquid absorbs 1 litre of gas at 1 bar. How much will it absorb at 5 bar?

a. 1 litre
b. 2 litre
c. 3 litre
d. 5 litre

A

d

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68
Q 
If you double the pressure on a gas, according to Boyle's law what will happen
to the volume and density?
a. Volume doubles Density doubles
b. Density doubles Volume remains same
c. Density is halved Volume is halved
d. Volume is halved Density is doubled
A

d

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69
Q 
What does the reference ± 0.25% marked on a 300 msw gauge, refer to in
depth?
a. 0.25 msw
b. 0.5 msw
c. 0.75 msw 
d. 0.1 msw
A

c

.25%x300= 0.75m

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70
Q

You have to pressurise a DDC with an FV of 15m3 to 122 msw. How much gas is required?

a. 55.39 m3
b. 74.4 m3
c. 183 m3
d. 198 m3

A

c

12.2x15= 183m3

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71
Q 
A diver suffering from decompression sickness is given a total of 6 cycles of 25 minutes each.  The consumption rate is 0.75ft ³at surface.  Chamber depth is 100fsw.  How much gas will be used?
a	453ft³									
b	425ft³
c	396ft³
d	341ft³
A

a

100+33/33=4.030x0.75x25x6= 453.4ft3

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72
Q 
A chamber is pressurised to 200 fsw.  The temperature on arriving at 200 fsw was 110°F.  At what depth would the chamber be after cooling to 68°F
a	  211fsw
b	  182fsw								
c	  152fsw  
d	  179fsw
A

b

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73
Q 
A liquid absorbs 1 cu.ft of gas at sea level.  How much will it absorb at 6 atm?
a	  7 cu.ft
b	12 cu.ft
c	  5 cu.ft
d	  6 cu.ft
A

d

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74
Q 
Using a 500 msw gauge, what does the reference marked on the gauge ± 0.25% refer in depth?
a	1 msw
b	1.25 msw							
c	1.5 msw
d	2.25 msw
A

b

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75
Q 
Assumming that air contains 21 % oxygen and 79 % nitrogen, what is the PO² and PN² in air at 165 fsw ?
a	1.56 atm and 4.02 atm
b	1.05 atm and 3.95 atm
c	1.26 atm and 4.74 atm
d      1.32 atm and 4.25 atm
A

c

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76
Q 
How much gas is required to pressurise a chamber system with a F.V. of 1400ft³ to a depth of 450 fsw
a	19420ft³
b	18529ft³
c      19091ft³								
d      17392ft³
A

c

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77
Q

What is the gas consumption of 2 divers at a depth of 138fsw for 6hours 27mins (1.25ft³/min consumption)
a 4009.3ft³
b 5202.7ft³
c 5011.7ft³
d 4044.2ft³

A

c

138+33/33=5.18x1.25= 6.47x2= 12.95x387= 5.011,65

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78
Q 
A chamber loses 15m³ of gas per day.  How many litres per hour does that relate to?
a	62.5 ltrs
b	652.5 ltrs
c	52 ltrs
d	625 ltrs
A

d

15000/24= 625l/h

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79
Q 
A chamber system has a volume of 1200 ft³ . What volume of gas would it take to pressurise it to 500 fsw ?
a	18763 ft³
b	18,182	ft³								
c	19382.1 ft³
d	17846 ft³
A

b

500/33=15.15 x 1200=18.182ft3

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80
Q
  1. After filling a bailout to 3500 psi. The bottle temperature is 105°F What will the pressure in the bail-out be when the temperature drops back to 68°F

a 3271 psi
b 3745 psi
c 3714 psi
d 3299 psi

A

a
Convert F° in R°= +460
3500/ 565x528= 3.271psi

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81
Q 
If a balloon has a volume of 5 litres on the surface, what will its volume be at 45 metres?
a	2 litres
b	1.5 litres
c	4.5 litres
d	1 litre
A

d

5/5.5= 0.9l
Boyles law

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82
Q 
A 12 litre bailout bottle is at a pressure of 300 bar.  What volume of gas is available to use (regulator working pressure 8 bar) dive depth is 140 msw.  How long would this gas last the diver?
	Gas Available		Time
a	3324 l			5 mins 54 secs
b	3324 l			5 mins 32 sec					
c	3324 l			6 mins 20 secs
d	2794 l			4 mins 50 secs
A 
b
300-15-8x12=3.324l
15x40=600l gas consumption ... So 3324/600= 5.54h
.54x60= 32min
5h32min
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83
Q
  1. If you pressurise a 25m³ chamber to 75m from a 48 bottle quad, by how much would the quad pressure drop by?
    a 88bar
    b 78bar
    c 75 bar
    d 68 bar
A

b

7.5x25= 187.5m3
Assuming 200 bar std quad
48x50x200= 480m3

In a simple rule of 3
If 200 bar = 480m3
X = 187.5m3

X= 78.12 bar

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84
Q 
Your company´s PO² during decompression is 500mb. At what depth would the O² % reach 21 % ?
a	12msw
b	14msw									
c	16msw
d	18msw
A

b

0.5/.21= 2.38-1x10= 13.8m

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85
Q 
30.	A 64 x 50 litre bottle quad contains gas at a pressure of 195 bar. What is the total volume of gas in the quad ?
a	656m³
b	592m³
c	468m³
d	624m³
A

d

64x50x195= 624m3

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86
Q 
Convert 5200 PPM to a %.
a	0.052%
b	52%
c	0.52%								
d	5.2%
A

c

5200/10000= 0.52%

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87
Q 
To convert degrees fahrenheit to absolute temperature you must add?
a	100
b	640
c	273
d	460
A

d

C to F + 273
F to R + 460

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88
Q 
3.	What is 65ºF expressed in celsius?
a	52ºc
b	18.3ºc									
c	31.2ºc
d	20ºc
A

b
F to c = -32 / 1.8
65-32/ 1.8= 18.3

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89
Q 
4.	How much does a 12 litre flask hold when charged to 200 bar?
a	240m3
b	25.20m3
c	4.8m3
d	2.4m3
A

d

12x200= 2400= 2.4m3

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90
Q 
Convert 1500 litres into cubic metres.
a	1.5m3									
b	15m3
c	30m3
d	150m3
A

A

1m3=1000l

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91
Q 
How much gas would be required to pressurise a chamber with a floodable volume of 20m3 to a depth of 65msw?
a	150m3
b	1300m3
c	130m3									
d	120m3
A

c

6.5x20= 130m3

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92
Q 
A bailout bottle has a F.V of 12 litres and is charged to 300 bar.  How much gas is available to the diver at a depth of 75m (hat working pressure of 8 bar)?
a	3.5m3
b	3.4m3									
c	3.6m3
d	4.0m3
A

b
300-8.5-8x12= 3402l

READY THE FUCKING QUESTION!!!!!!!

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93
Q 
A 64 bottle quad, each have a floodable volume of 50 litres. How much gas does it contain at 195 bar?
a	195m³
b	624m³									
c	6.24m³
d	524m³
A

b

64x50x195=624m3

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94
Q 
A bailout bottle has a F.V of 10 litres and is charged to 200 bar.  How long would it last a diver at a depth of 50 msw (40 l/min and 8 bar reg pressure)?
a	5mins
b	4.6 mins							
c	6 mins
d	7.7 mins
A

D
200-6-8=186x10=1860
6x40=240l sooo 1860/240= 7.75 min = 7min45sec

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95
Q 
What is the partial pressure of O2 at 35 msw if the breathing gas is air?
a	500 mb
b	400 mb
c	945 mb								
d	735 mb
A

c

4.5x.21=0.945 bar or 945mbar

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96
Q 
If a diver has a litre of gas in solution in his body at 1 bar(A), how much of the same gas would he have in solution at 40 msw?
a	1 ltr
b	4 ltrs
c	5 ltrs									
d	6 ltrs
A

c

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97
Q 
A bell is blown down to a depth of 120 msw with a temperature at depth of 38ºC.  What would the reading by gauge be after cooling to 28ºC?
a	116 msw								
b	126 msw
c	114 msw
d	120 msw
A

a

13/ 38+273= 0.0418x 301=12.58-1x10= 115.81msw

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98
Q 
During pressurisation a bottle reached a temperature of 42ºC.  If the start pressure was 200 bar what would be the pressure after cooling back to 25ºC?
a	179 bar
b	180 bar
c	195 bar
d	189 bar
A

D

200/315x298= 189.20

99
Q 
What is the amount of gas required to blowdown a chamber with a F.V of 25m3 from 80 msw to 110 msw?
a	75m3									
b	70m3
c	55m3
d	50m3
A

a

3x25=75m3

100
Q 
How much gas would a diver consume over 3 hours at a depth of 75 msw if his consumption was 35 l/min?
a	47.3m3
b	53.6m3									
c	58m3
d	42.5m3
A

b

8.5x35=297.5l x 180min= 53.550m3

101
Q 
Convert 0.28% into PPM.
a	2800 ppm								
b	2.8 ppm
c	28000 ppm
d	280 ppm
A

a

Multiply by 10.000

102
Q 
What is the PP Nitrogen at a depth of 30msw breathing air?
a	0.21 bar
b	32 bar
c	0.32 bar
d	3.2 bar
A

d

4x0.79=3.16bar

103
Q 
A compressor has an output of 60m3 per hour at 10 bar outlet pressure.  How many divers will the compressor support at a diving depth of 50msw?
a	8
b	6
c	4									
d	2
A

c
As it stands no divers…. 10bar not sufficient minimum of 16bar (10 plus ambient)if does have a 16 bar….

6x35=210l/m
60m3 per hour = 1000l per min divide by 210= 4 divers.

104
Q 
A diver is working at 80 msw, breathing from 16x50litre quad at a pressure of 150 bar.  How long can he work for (assume the quad will be changed over at 40 bar)?
a	5 hrs 10 mins
b	4 hrs 40 mins								
c	6 hrs 10 mins
d	3 hrs 50 mins
A 
b
Volume available 16x50x110=88000
Diver consumption 9x35=315 so 88000/315= 279.36min
279.36/60= 4.65h.     .65x 60= 39min
4h39min
105
Q 
23.	What is the PPO2 at 47msw if the breathing gas is air?
a	0.37 bar
b	1.2 bar									
c	0.99 bar
d	0.21 bar
A

b

5.7x.21=1.19bar

106
Q 
A container measures 10m (long) x 3m (wide) x 4m (high), it draws a 2m draft.  What is the upthrust received on seabed?
a	60te
b	68te
c	61.8te									
d	16.8te
A

c

10x3x2=60x 1.03=. 61.8t

107
Q 
Name the three states buoyancy.
a	upthrust, buoyancy, displacement
b	positive, neutral, negative						
c	length, breadth, height
d	positive, neutral, upthrust
A

b

108
Q 
A pontoon displaces 6m3 of seawater and weighs 5 tons, is the pontoon positively or negatively buoyant and by how much?
a	1.18 tons positive							
b	1 ton negative
c	1.18 tons negative
d	1 ton positive
A

a
6 x 1.03= 6.18 displacement - 5 ton= 1.18t positive

Ps: when the displacement is higher than the subject weight. Will be positive buoyant

109
Q 
A sealed pipe with a diameter of 1 metre and 8 metres long and weighs 8 tons is lying in a river bed.  How much water must be displaced from a lifting bag to initiate a lift?
a	1.53m3
b	1.92m3
c	1.72m3								
d	2m3
A

c
Volume of cilynder. PI x Rsquare x lenght
3.14 x (0.5)2 x 8= 6.28 displacement of the water
8-6.28=1.72m3
Ps: remember is fresh water… salt water should be multiply by 1.03 the displacement

110
Q

A diving bell displaces 5m3 of sea water and weights 4.8t.
Is the bell positive buoyant ?
Would be positive buoyant in fresh water?

A
  • yes, the upthrust is 5.15 tonnes

- yes, the upthrust is 5 tonnes

111
Q

A diving bell displaces 180ft3 of sea water and weights 5.2 imperial tons.

  • Is the bell positive buoyant?
  • what if weights 5.2 US tons
A
  • no, the upthrust is 5.17 imperial tons

- yes, the upthrust is 5.79 US ( Did you use 2000lbs= 1 ton)

112
Q

A block of concrete 1mx1mx1m is lying on the seabed density of the concrete is 2400Kg/m3.
How much force is required to lift the block clear of the seabed? (Ignore any suction)

A

1.37 tonnes

2400/1000(kg/m3)= 2.4t
1x1x1=1x1.03= 1.03t
2.4-1.03= 1.37 tonnes
113
Q

A welding habitat weights 25 tonnes in air. It displaces 12m3.
What is the weight in sea water ?( apparent weight)

A

12.64 tonnes

12x1.03=12.36
25-12.36= 12.64t

114
Q

A closed length of pipe of pipe weights 12 imperial tons (2240lbs) and displaces 140ft3. How many 1 ton lifting bags would you need to lift it clear of the seabed? (Ignore suction)

A

Need lift of 7.98 tons. So 8 lifting bags.

12x2240=26.880
140x64.38= 9.013.2

26.880-9.013,2= 17.866,8/2240= 7.97tonnes
8 lifting bags

115
Q

A chamber is at 345 fsw and 31°C. The temperature drops to 26°C.
What would the depth decrease by?

A

6.2 fsw

345/33 + 1 = 11.45/304 = 0.0376 X 299 = 11.26 - 1 X 33 = 338.78

345 - 338.78= 6.2.fsw

PS: Calculations with Chambers and imperial, convert to absolute pressure!!!!

116
Q

At the start of the shift, chamber 145 msw and 32°C. During the shift the temperature 28°C. How much would the depth have decrease?

A

2 msw

145/305 = 0.4754 X 301= 143m
145-143= 2msw
117
Q

A diver is At 30 msw. What is the absolute pressure on the diver?

A

4 bar

118
Q

A diver is At 120 fsw. What is the absolute pressure on the diver?

A

4.63 Ata

119
Q

A diver is At 30 msw. What is the absolute depth of the diver?

A

40m

120
Q

What is 40ºC in ºF?

A

104ºF

121
Q

What is 40ºF in ºC?

A

4.44ºC

122
Q

What is 40ºC in ºK?

A

313ºK

123
Q

What is 40ºF in ºR?

A

500ºR

124
Q

A diver is working at 140 msw. What is his gas consumption?

A

525 l/min or 0.525 m3/min

125
Q

A diver is working at 120 fsw. What is his gas consumption?

A

5.79 ft3/min

126
Q

A diver is working at 15 msw. How much gas will he use in 40 minutes?

A

3.5 m3

127
Q

A 64 x 50 litre quad holds gas at pressure of 200 bar. what is the volume of gas in the quad?

A

640m3

128
Q

A 64 x 50 litre quad holds gas at a pressure of 200 bar. The diver is working at 140 msw. If the diving supervisor changes over the quad at 40 bar, what volume of gas is available for the diver?

A

512m3

129
Q

A 64 x 50 litre quad contains gas at a pressure of 150 bar. What is the total volume of gas in the quad?

The quad in the question above will be changed over when the pressure falls to 35 bar. What volume of gas is available to the divers?

A

480 m3

368 m3

130
Q

A 16 x 50 litre quad holds gas at a pressure of 180 bar. The diver is working at 100 msw. If the diving supervisor changes over the quad at 40 bar, how long can the diver work for?

A

4hours 51 minutes

131
Q

Two divers are working at 165 msw, breathing from a 16 x 50 litre quad at a pressure of 200 bar. How long could they work for before the quad is changed over at 40 bar?

A

1h 44 min

132
Q

A 64 x 50 litre quad is at a pressure of 180 bar. It can be used until the pressure falls to 30 bar. How much gas is available for use?

A

480 m3

133
Q

A 16 x 50 litre quad is at a pressure of 40 bar. What volume of gas will be needed to fill it to a pressure of 200 bar?

A

128 m3

134
Q

A quad contains 22,400 ft3 of gas when it is at a pressure of 3000 psi. It is at a pressure of 2400 psi. If the diving supervisor changes over the quad at 500 psi, what volume of gas is available for the diver?

A

14.186.7 ft3

135
Q

A quad contains 5800 ft3 when it is at a pressure of 3000 psi. How much gas does it contain when the pressure is 1200 psi?

A

2320 ft3

136
Q

A quad contains 21650 ft at a pressure of 2800 psi. How much gas does it contain when the pressure is 600 psi?

A

4639 ft3

137
Q

2 divers are breathing from a quad which contains 22,500 ft of gas when it’s at a pressure of 3000 psi. Just now, it’s at 2750 psi. They’re working at 500 fsw. How long can they work for before the quad is changed over at 500 psi?

A

6h 58 min

138
Q

A diver is working at 280 fsw. He’s breathing from a quad which is at a pressure of 3000 psi and contains 5800 ft3 of gas. The quad will be changed over at 450 psi. How long can the diver work for, before the quad is changed over?

A

6h 56 min

139
Q

A lightweight LP compressor supplies 8 ft3/min at 250 psi. Two divers are planning to work at 80 fsw. Is the compressor suitable?

A

Not suitable. The divers require 8.56 ft3/min

140
Q

An LP compressor supplies 30 ft/min at 300 psi. The diver plans to work at 100 fsw. Is the air supply sufficient?

A

Suitable. The only requires 5.04 ft3/min

Volume 206 psi

141
Q

A lightweight LP compressor supplies 120 l/min at 15 bar. A diver is planning to work at 20 msw. Is the compressor suitable?

A

Suitable. The diver only requires 105 l/min

142
Q

A lightweight LP compressor delivers 300 l/min at a pressure of 15 bar. Two divers are planning to work at 30 msw. Is the air supply sufficient?

A

suitable. the divers only requires 280 l/min

143
Q

Two divers are planning to work at 75 fsw, using an LP compressor. What is the minimum delivery volume and pressure that they require?

A

Minimum delivery 8.18 fe/min,minimum pressure 195.1psi (13.27AT)

75+33/33= 3.27 x1.25x2= 8.18ft3

3.27+10 (reg) = 13.27x 14.7= 195.1 psi

144
Q

A diver is working at 180 msw and has a 12 litre bail out bottle at 180 bar. How long would it last him in an emergency?

A

2.38 minutes or 2 minutes 23 seconds

145
Q

A bail out bottle has a floodable volume of 12 litres and is filled to 200 bar. How much time has a diver got if his surface supply fails at 120 msw?

A

4.08 minutes or 4 minutes 5 seconds

146
Q

A bail out bottle contains 100 ft3 of gas when it’s at 3500 psi. During the dive it’s at a pressure of 3000 psi. If the diver’s surface supply fails at 450 fsw, how long has he got to get back to the
bell?

A

3.43 minutes or 3 minutes 26 seconds
Fail at 3000 so….
450+33/33= 14.63+10(regulator)= 24.63x14.7= 362.15
3000-362.15 = 2.638x100/3500= 75.37 litres available
consumption: 14.63x1.5 = 21.95l/min

75.37/21.95 = 3.43 min or 3min 26 sec

147
Q

A bail out cylinder is at a temperature of 30°C after filling to 200 bar. What will the pressure be if the temperature drops to 4°C?

A

182.8 bar

148
Q

A bail out cylinder is at a temperature of 90°F after filling to 3000 psi. What will the pressure be if the temperature drops to 40°F?

A

2727.3 psi

149
Q

After filling to 200 bar, a bail out bottle is at a temperature of 35°C. What will the pressure be when the temperature drops to 12°C?

A

185 bar

150
Q

After filling to 3500 psi, a bail out bottle is at a temperature of 75°F. What will the pressure be when the temperature drops to 38°F?

A

3258 psi

151
Q

A quad is filled to 200 bar at night, when the air temperature is 20°C. During the day,the temperature rises to 40°C (you’re in Abu Dhabi). What will the quad pressure be?

A

214 bar

152
Q

A body tissue can absorb 0.27 litres of nitrogen when the PPN2 is
0.79 ATA. How much can it absorb when the PPN2 is 1.4 ATA?

A

0.491 litres

153
Q

A diver is breathing air at 50 msw. What is the PPN2?

A

4.74 bar

154
Q

A diver at 150 fsw is breathing a 12% mix. What is the PP02 in his mix?

A

0.665 at

155
Q

What is the PP02 in a chamber at 60 fsw if the oxygen percentage is 21%?

A

0.592 at

156
Q

What is the PP02 and PPN2 in air at 150 fsw? (Assume that air contains 21% oxygen and 79% nitrogen.)

A

PPO2: 1.16 at
PPN2: 4.38 at

157
Q

A diver is breathing a 40% nitrox mix at 20 msw. What is the

PP02? What is the PPN2?

A

PP02 1.2 bar, PPN2 1.8 bar

158
Q

A diver is breathing a 40% nitrox mix at 17 msw. What is the EAD?

A

10.51 msw

159
Q

A diver is breathing a 36% nitrox mix at 100fsw. What is the EAD?

A

74.75fsw

160
Q

What is the EAD for a 34% nitrox mix at 30 msw?

A

23.41msw

161
Q

What is the EAD for a 40% nitrox mix at 110 fsw? Why couldn’t you use this mix at 110 fsw?

A

75.6 fsw. This mix can’t be used because the PP02 is 1.73 bar. The recommended maximum in nitrox diving is 1.4 bar.

162
Q

You want to pressurise a 45m3 chamber system to 130 msw.

What volume of gas do you need?

A

585 m3

163
Q

What volume of gas would it take to pressurise a 1500ft3 chamber system to 500 fsw?

A

22727 ft3

164
Q

A chamber system has a volume of 35m3. What volume of gas would it take to pressurise it to 120 msw?

A

420 m3

165
Q

What volume of gas would it take to pressurise a 38m3 chamber system to 195 msw?

A

741 m3

166
Q

A chamber system has a volume of 875 ft3. What volume of gas would it take to pressurise it to 400 fsw?

A

10606 ft3

167
Q

A chamber is at 400fsw. The chamber temperature drops from 81’F to 82°F. If the LST didn’t add any gas, what would the depth change to?

A

399 fsw

168
Q

A chamber is at a depth of 120 msw and the temperature is 33°C. If the temperature fell to 30°C (and the LST didn’t add any gas!) what would the depth change be?

A

1.27 msw

169
Q

A chamber is at 160 msw and 29°C. At the start of the shift, the temperature was 32°C. If the life support crew had not added gas to maintain depth, by how much would the depth have decreased?

A

1.67 msw

170
Q

A chamber is at 345 fsw and 86°F. The temperature drops to 76°F. If the life support crew took no action, what would the depth decrease to?

A

338.1 fsw

171
Q

A diving bell displaces 5.5 m3 of sea water and weighs 4.75 tonnes. Is the bell positively buoyant?

A

Positively buoyant by {5.665- 4.75} tonnes = 0.915 tonnes

172
Q

A diving bell displaces 200 ft3 of sea water and weighs 5.8 imperial tons (that’s 2240 lbs to the ton). Is the bell positively buoyant?

A

Negatively buoyant by {5.80- 5.75) tons= 0.05 tons

173
Q

A diving bell displaces 6m3 of sea water and weighs 6.1 tonnes. Is the bell positively buoyant?

A

Positively buoyant by (6.18- 6.10) tonnes = 0.08 tonnes

174
Q

Would the bell in the question above be positively buoyant in fresh water?

A

Negatively buoyant by (6.10- 6.00) tons= 0.01 tons

175
Q

A diving bell displaces 180 ft of sea water and weighs 5.2 imperial tons. Is the bell positively buoyant?

A

Negatively buoyant by (5.20- 5.17) tons= 0.03 tons (UK)

176
Q

A diving bell displaces 180 ft of sea water and weighs 5.2 US tons. Is the bell positively buoyant?

A

Positively buoyant by (5.79- 5.20) tonnes = 0.59 ton (US)

US ton = 2000lb

177
Q

A steel pontoon is 5m x 3m x 3m and is floating with 2m submerged in fresh water. What is the weight of the pontoon?

How much weight can you put in the pontoon in the question above before it sinks?

A

30 tonnes

15 tonnes

178
Q

A block of concrete, 1.0m by 1.2m by 1.5m, is lying on the seabed. What is its weight in water and in the air?
(concrete 2400Kg/m3)

A
  1. 32 tonnes in air
  2. 46 tonnes in water

1x1. 2x1.5= 1.8x2400= 4320/1000 = 4.32T
1. 8x1.03= 1.854 ……….4.32 - 1.854= 2.46T

179
Q

A block of concrete, 1m by 1m by 1m, is lying on the seabed. How much force is required to lift the block clear of the seabed?
(Ignore any suction.)

A

1.37 tonnes

1x1x1 = 1x 2400/ 1000= 2.4T

1x1. 03= 1.03T
2. 4 - 1.03 = 1.37T

180
Q

A welding habitat displaces 14m3 and weighs 28 tonnes in air. What does it weigh in sea water?

A

13.58 tonnes

14x 1.03 = 14.42
28-14.42= 13.58T

181
Q

A closed length of pipe weighs 14 imperial tons and displaces 140 ft3. How many 1 ton lifting bags would you need to lift it clear of the seabed? (Ignore suction.)

A

10 bags (Weight in water is 9.98 tons)

140x64.38= 9.013,2/2240 = 4.023T
14-4.023= 9.97T
10 lifting bags

182
Q

A blind flange is made of 1 inch steel plate and is 30cm in diameter. What volume of fresh water will it displace? (Ignore the bolt holes.)

A

1.796 litres
V= PIxR(square)xlenght
V= 3.142x15(square)x2.54(1inch=2.54cm)
V= 3.142x225x2.54= 1.796Litres

1.796 x 1 = 1.796 litres

PS: If were sea water would be X 1.03

183
Q

A flooded spoolpiece has an outside diameter of 30 cm, wall thickness of 3 cm and a length of 12 metres. What does it weigh in air? What does it weigh in seawater? {Ignore the flanges.) (7900kg/m3 steel)

A

Weight in air 2409.5 kg, Weight in water 2095.35 kg

spool= PI x lenght x wall thickness x(outside diameter-wall thickness)

V= 3.142 x 12 x 0.03 x (0.3-0.03) = 0.305kg x 7900= 2.409,5kg

  1. 305x1.03= 0.314
  2. 5-314= 2095.35
184
Q

A flooded spoolpiece has a 16 inch outside diameter and a wall thickness of 1 inch. It is 30 feet long. What does it weigh in air? What does it weigh in seawater? (Ignore the flanges and use pounds.)

Remember density of steel in imperial 483.2 ft3/lbs

A

Weight in air 4.725,69 lbs, Weight in water 4096,06 lbs (The volume is 9.78ft3)

V= pi x l x wt ( od - wt )

V = 3.142 x 30 x 0.083 ( 1.333 - 0.083)
V = 9.78
  1. 78 x 483.2 = 4.725,69
  2. 78 x 64.38 = 629.63

4.725,69 - 629,63 = 4096,06

185
Q

A concrete DMA weighs 1 tonne in air. What is its approximate weight in seawater?

A

0.57 tonnes

PS:
If you’re dealing with a solid steel object:
Weight in sea water = weight in air x 0.87
If you’re dealing with a solid concrete object:
Weight in sea water = weight in air x 0.57

186
Q

A length of steel SBM mooring chain weights 5 tonnes in air. What is its approximate weight in water?

A

4.35 tonnes

PS:
If you’re dealing with a solid steel object:
Weight in sea water = weight in air x 0.87
If you’re dealing with a solid concrete object:
Weight in sea water = weight in air x 0.57

187
Q

What is the absolute pressure at a depth of 254 msw?

A

26.4 bar

188
Q

What is the absolute pressure at a depth of 254 fsw?

A

8.69 ata

189
Q

A diver is working at 120 msw for 4 hours. What volume of gas will he use?

A

109.2 m3

190
Q

A diver is working at 100 fsw for 30 minutes. What volume of gas will he use?

A

151.2 ft3

191
Q

Two divers are working out of the bell at 75 msw. What volume of gas will they use in 4 hours?

A

142.8 m3

192
Q

An air diver is working at 60 fsw for 20 minutes. What volume of air will he use?

A

70.45 ft3

193
Q

A 64 x 50 litre quad contains gas at a pressure of 100 bar. What is the total volume of gas in the quad?

The quad in Question 7 will be changed over when the pressure falls to 40 bar. What volume of gas is available to the diver?

In Question 8, the diver is working at 130 msw. How long can he work for before the quad is changed over?

A

320 m3

192 m3

6 hours 32 minutes

194
Q

A diver is working at 80 msw, breathing from a 16 x 50 litre quad at a pressure of 150 bar. How long could he work for? (Assume that the quad will be changed over at 40 bar.)

A

4 hours 39 minutes

195
Q

A 64 x 50 litre quad is at a pressure of 205 bar. It can be used until the pressure falls to 30 bar.
How much gas is available for use?

A

560 m3

196
Q

A 12 x 50 litre quad is at a pressure of 25 bar. What volume of gas will be needed to fill it to a pressure of 200 bar?

A

105 m3. It is only a 12 bottle quad!

197
Q

A bail-out bottle has a volume of 12 litres and contains gas at a pressure of 200 bar. If the diver is working at 100 msw, what volume of gas is available to him in an emergency?

A

2.15 m3

198
Q

A diver is working at 195 msw, breathing from a 16 x 50 litre quad at a pressure of 110 bar. The quad will be changed over at 40 bar. How long could he work for?

A

1 hour 18 minutes

199
Q

A quad contains 5800 ft3 when it is at a pressure of 3000 psi. How much gas does it contain when the pressure is 1800 psi?

A

3480 ft3

200
Q

A quad contains 21650 ft3 at a pressure of 2800 psi. How much gas does it contain when the pressure is 600 psi?

A

4639 ft3

201
Q

A quad contains 22,500 ft3 at a pressure of 3000 psi. It can be used until the pressure drops to
450 psi. What volume of gas is available to the diver?

A

19125 ft3

202
Q

A diver is working at 250 fsw. He’s breathing from a quad which contains 22,500 ft3 of gas when it is at a pressure of 3000 psi at the start of his dive. Just now, it is at 2750 psi. How much longer could the diver work for? (Assume that the quad will be changed over at 500 psi.)

A

26 hours 13 minutes

203
Q

A diver is working at 380 fsw. He is breathing from a quad which contains 22,500 ft3 of gas at a pressure of 3000 psi. The quad will be changed over at 450 psi. How long could the diver work for?

A

20 hours 22 minutes

204
Q

A quad contains 5400 ft3 at a pressure of 2800 psi. It can be used until the pressure drops to 400 psi. What volume of gas is available to the diver?

A

4629 ft3

205
Q

An LP compressor supplies 30 ft3/min at 300 psi. The diver plans to work at 100 fsw. Is the air supply sufficient?

A

YES

206
Q

A lightweight LP compressor delivers 250 l/min at a pressure of 15 bar. Two divers are planning to work at 30 msw. Is the air supply sufficient?

A

NO

207
Q

Two divers are planning to work at 60 fsw, using an LP compressor. What is the minimum delivery volume and pressure that they require?

A

7.04 ft3 per minute, 188 psi (12.82 ata)

208
Q

A bail-out bottle has a floodable volume of 12 litres. How much time has a diver got if his surface supply fails at 200 msw? The bail-out bottle is at a pressure of 180 bar.

A

2.1 minutes or 2 minutes 7 seconds

209
Q

A bail-out bottle contains 100 ft3 at 3500 psi. It is at a pressure of 3000 psi. If the diver’s surface supply fails at 500 fsw, how long has he got to get back to the bell?

A

3.1 minutes or 3 minutes 6 seconds

210
Q

After filling to 200 bar, a bail-out bottle is at a temperature of 30°C. What will the pressure be when the temperature drops to 4°C?

A

183 bar gauge

211
Q

After filling to 3500 psi, a bail-out bottle is at a temperature of 40°C. What will the pressure be when the temperature drops to 4°C?

A

3097 psi

212
Q

Assuming that air contains 21% oxygen and 79% nitrogen, what is the pO2 and pN2 in air at 165 fsw?

A

1.26 ata, 4.74 ata

213
Q

A chamber system has a volume of 40 m3. What volume of gas would it take to pressurise it to
150 msw?

A

600 m3

214
Q

A chamber system has a volume of 1200 ft3. What volume of gas would it take to pressurise it to
500 fsw?

A

18180 ft3

215
Q

A chamber system has a volume of 38 m3. What volume of gas would it take to pressurise it to
212 msw?

A

805.6 m3

216
Q

A chamber system has a volume of 875 ft3. What volume of gas would it take to pressurise it to
355 fsw?

A

9412 msw

217
Q

At the start of the shift, a chamber is at 145 msw and 32°C. During the shift, the temperature fell to
28°C. If the life support crew had not added gas to maintain depth, by how much would the depth have decreased?

A

2 msw

218
Q

A chamber is at 345 fsw and 31°C. The temperature drops to 26°C. If the life support crew took no action, what would the depth decrease by

A

6.2 fsw

219
Q

A diving bell displaces 5 m3 of sea water and weighs 4.8 tonnes. Is the bell positively buoyant?

Would the bell be positively buoyant in fresh water?

A

Yes, the upthrust is 5.15 tonnes

Yes, the upthrust is 5 tonnes

220
Q

A diving bell displaces 180 ft3 of sea water and weighs 5.2 imperial tons. Is the bell positively buoyant?

A

No, the upthrust is 5.17 imperial tons (see example 52)

221
Q

A diving bell displaces 180 ft3 of sea water and weighs 5.2 US tons. Is the bell positively buoyant?

A

Yes, the upthrust is 5.79 US tons (did you use 2000 lbs = 1 ton?)

222
Q

A block of concrete, 1m x 1m x 1m, is lying on the seabed. The density of concrete is 2400 kg/m3. How much force is required to lift the block clear of the seabed?

A

1.37 tonnes

223
Q

. A welding habitat weighs 25 tonnes in air. It displaces 12 m3. What does it weigh in sea water?

A

12.64 tonnes

224
Q

A closed length of pipe weighs 12 imperial tons (2240 lbs) and displaces 140 ft3. How many 1 ton lifting bags would you need to lift it clear of the seabed? (Ignore suction.)

A

You need a lift of 7.98 tons. That is, 8 lifting bags.

225
Q

A diver is at 30 msw. What is the absolute pressure on the diver?

A

The gauge pressure is 3 bar

The absolute pressure is 3 + 1 : 4 bar

226
Q

A diver is working at 140 msw. What is his gas consumption?

A

0.525 m /min

227
Q

A diver is working at 120 fsw. What is his gas consumption?

A
  1. 64 x 1.25 ft3

5. 8ft /min

228
Q

A 64 x 50 litre quad holds gas at a pressure of 200 bar. The diver is working
.- at 140 msw. If the diving supervisor changes over the quad at 40 bar, what volume of gas is available for the diver?

A

512m3

229
Q

A 16 x 50 litre quad holds gas at a pressure of 180 bar. The diver is working at 100 msw. If the diving supervisor changes over the quad at 40 bar, how long can the diver work for?

A

4 hours 51 minutes

230
Q

A lightweight LP compressor supplies 8ft/min at 250 psi. Two divers are planning to work at 80 fsw. Is the compressor suitable?

A
  1. 27 psi: suitable

8. 56ft /min: not sufficient

231
Q

A lightweight LP compressor supplies 120 l/min at 15 bar. A diver is planning to work at 20 msw. Is the compressor suitable?

A

The supply pressure is 15 bar, which is suitable.

The compressor supplies 120 L/min. This is sufficient and the dive could go
ahead as planned.

232
Q

A diver is working at 180 msw and has a 12litre bail out bottle at 180 bar. How long would it last him in an emergency?

A

2 min23 sec

Note that the time of 2.38 minutes limits his umbilical length to 23 metres from the bell.

233
Q

You want to pressurise a 45 m3 chamber system to 130 msw. What volume of gas do you need?

A

585m3

234
Q

A diver is at 120fsw. What is the absolute pressure on the diver?

A

The gauge pressure is 3.63 AT

The absolute pressure +s 3.63 + 1 ; 4.63 ATA

235
Q

Convert 126 fsw into msw

Convert 98 msw into fsw

A

126fsw = 38.4msw

98msw = 321.44fsw

ratio 3.28 gauge

236
Q

Convert 196 bar into PSI?

Convert 155 psi into bar?

A

196 bar = 2842 psi

155 psi = 10.68 bar

Ratio of 14.5

237
Q

Convert 28 C into degress F

Convert 50 F into Celsius

A

28 C = 82.4 F

50 F = 10 C

C to F = x 1.8 + 32
F to C = -32 divide by 1.8

238
Q

Convert 368 fsw into ATA

A

338 fsw = 12.15ATA

239
Q

Convert 49 m2 into ft2

A

49 m2 = 527.24 ft2

ratio of 10.76

240
Q

Convert 98 litres into cu ft.

Convert 5.7 cu ft into litres

A

98 litres = 3.46 cu ft

5.7 cu ft = 161.42 litres

Ratio of 28.32

241
Q

How many cubic feet in a cubic meter?

A

There are 35.32 cubic feet in cubic meter

242
Q

How many litres in a cubic foot?

A

There are 28.32 litres in a cubic foot

243
Q

A wet bell receives an up thrust of 16,095 lbs when totally submerged and it weighs 7.5 tons. How much extra
buoyancy is needed to make it 500 lbs positive?
a. 435 lbs
b. 705 lbs
c. 935 lbs
d. 1205 lbs

A

d

7.5 X 2240 = 16800 - 16095 = 705 + 500 = 1205 lbs

Air Diving Supervisors QUESTIONS (12 decks)

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