Physics Flashcards
What is the absolute pressure at a depth of 254 msw?
26.4 bar
What is the absolute pressure at a depth of 254 fsw?
8.69 ata
A diver is working at 120 msw for 4 hours. What volume of gas will he use?
109.2 m3
A diver is working at 100 fsw for 30 minutes. What volume of gas will he use?
151.2 ft3
Two divers are working out of the bell at 75 msw. What volume of gas will they use in 4 hours?
142.8 m3
An air diver is working at 60 fsw for 20 minutes. What volume of air will he use?
70.45 ft3
A 64 × 50 litre quad contains gas at a pressure of 100 bar. What is the total volume of gas in the quad?
320 m3
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?
192 m3
In Question 8, the diver is working at 130 msw. How long can he work for before the quad is changed over?
6 hours 32 minutes
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.
4 hours 39 minutes
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?
560 m3
A 12 × 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?
105 m3 . It’s only a 12 bottle quad!
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?
2.15 m3
A diver is working at 195 msw, breathing from a 16 × 50 litre quad at a pressure of 110 bar. The quad will be changed over at 40 bar. How long could he work for?
1 hour 18 minutes
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?
3480 ft3
A quad contains 21650 ft3 at a pressure of 2800 psi. How much gas does it contain when the pressure is 600 psi?
4639 ft3
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?
19125 ft3
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.
26 hours 13 minutes
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?
20 hours 22 minutes
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?
4629 ft3
An LP compressor supplies 30 ft3/min at 300 psi. The diver plans to work at 100 fsw. Is the air supply sufficient?
Yes
A lightweight LP compressor delivers 250 I/min at a pressure of 15 bar. Two divers are planning to work at 30 msw. Is the air supply sufficient?
No
Two divers are planning to work at 60 fsw, using an LP compressor. What is the minimum delivery volume and pressure that they require?
7.04 ft3 per minute, 188 psi (12.82 ata)
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.
2.1 minutes or 2 minutes 7 seconds
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?
3.1 minutes or 3 minutes 6 seconds
A bail-out bottle is filled to 200 bar and is at a temperature of 30°C, what is the pressure when the temperature drops to 4°C?
183 bar gauge
After being filled to 3500 psi, a bail out bottle is 40 degrees centigrade. What will the pressure be when it drops to 4 degrees centigrade?
3097 psi
A diver @ 250 fsw is breathing a 15 % mix. What is the p02 in his mix?
1.287 ata
What is the pO2 in a chamber at 80 msw with an oxygen percentage reading of 4.5%?
405 mb
What is the P02 for a diver at 125 msw breathing a 4% mix?
540mb
What is the P02 for a diver at 165 msw breathing a 4% mix?
700 mb
What is the P02 for a diver at 340 fsw breathing a 6% mix?
.678 ata
What is the P02 for a diver at 60 msw breathing an 18% mix?
1.26 bar
What is the P02 in a chamber at 50 fsw if the oxygen percentage is 23%?
.578 ata
What is the oxygen percentage in a chamber at 108 msw if the P02 is 400 mb?
3.39 %
What is the percentage of oxygen in a chamber at 327 fsw if the pO2 is 0.42 ata?
3.85 %
What is a suitable mix for a saturation dive at 600 fsw requiring a pO2 between 0.5 and 0.8 ata?
2.6 % and 4.2 %
What is the maximum depth (in msw) you could use a 15 % mix for a pO2 between 1.2 and 1.6 bar?
96.7 msw
During a bounce dive to 80 msw, divers require a P02 between 1.2 and 1.6 bar. What is a suitable mix?
Anything between 13.3 % and 17.78 %
What is a suitable mix for a saturation dive at 208 msw requiring a pO2 between 550 and 750 mb?
Anything between 2.52 % and 3.44 %
What are the pO2 and pN2 in air at 165 fsw assuming air contains 21% oxygen and 79% nitrogen?
1.26 ata and 4.74 ata
How deep could a diver go with a hydrox mix containing 1% oxygen without exceeding a pO2 of 750 mb?
740 msw
To make 200 bar of 9%, using 2% and 12%, what pressure of each gas do you need?
140 bar @ 12 % and 60 bar @ 2 %
To make 180 bar of 6%, using 2% and 18%, what pressure of each gas do you need?
45 bar @ 18 % and 135 bar @ 2 %
To make 3000 psi of 23%, using 12% and 50%, what pressure of each gas do you need?
868 psi of 50 % and 2132 psi of 12 %
To make 2500 psi of 12%, using 2% and 18%, what pressure of each gas do you need?
938 psi of 2 % and 1562 psi of 18 %
What will the final pressure of the mixture be if you have 100 bar of 4% and want to turn it into 10% by pumping in 20%?
160 bar
What will the final pressure of the mixture be if you have 45 bar of 2% and want to turn it into 10% by pumping in 18%?
90 bar
What will the final pressure of the mixture be if you have 1800 psi of 1.5% and want to turn it into 4% by pumping in 16%?
2175 psi
What will the final pressure of the mix be if you have 600 psi of 2% and want to turn it into 6% by pumping in 18%?
800 psi
If you have 50 bar of 2%, 40 bar of 4% and want to mix them together and add 23% to make the mix up to 8%, what will the final pressure be?
121 bar
If you have 500 psi of 6%, 400 psi of 4% and want to mix them together and add 16% to make the mix up to 12%, what will the final pressure be?
2450 psi
A chamber is to be pressurised to 90 msw using 12% and 2%. What depth of 12% should you use? The final pO2 must be 600 mb?
21 msw
A chamber is to be pressurised to 250 fsw using a mix of 2% and 16%. What depth of 16% should you use? The final pO2 must be 0.5 ata.
33 fsw
Depth of rich mix (fsw) = (3300 x (ppO2 required (ata) - ppO2 present)) - (bottom depth (fsw) x % weak
mix) / (% rich mix - % weak mix)
ppO2 required = 0.5 ata
ppO2 present = 0.21 ata
Bottom depth = 250 fsw
% weak mix = 2
% rich mix = 16
Depth of rich mix = ((3300 x (0.5 - 0.21)) - (250 x 2)
16 - 2
= (3300 x 0.29) - 500/ 14
= (957 - 500)/14
= 457/ 14
= 32.6 fsw
What depth of 18% should you add to pressurise a chamber to 500 fsw using 18% and 1%, with a final pO of 0.6 ata?
46.3 fsw
You want to pressurise a chamber to 120 msw, using 20% and 1.5%. The final pO2 must not
exceed 650 mb. What depth of 20% should you add to start the pressurisation?
14 msw
A chamber system has a volume of 40 m3. What volume of gas would it take to pressurise it to
150 msw?
600 m3
A chamber system has a volume of 1200 ft3. What volume of gas would it take to pressurise it to
500 fsw?
18180 ft3
A chamber system has a volume of 38 m3. What volume of gas would it take to pressurise it to
212 msw?
805.6 m3
A chamber system has a volume of 875 ft’3 What volume of gas would it take to pressurise it to
355 fsw?
9413 ft3
A chamber system has a volume of 30 m3. It is to be pressurised to 90 msw, with 21 msw of 12% and
69 msw of 2%. What volume of each gas would be needed?
63 m3 of 12% and 207 m3 of 2%
A chamber system has a volume of 1100 ft3. It is to be pressurised to 620 fsw, with 39 fsw of 18%
and 581 fsw of 1%. What volume of each gas would be needed?
1300 ft3 of 18% and 19367 ft3 of 1%
A chamber system has a volume of 45 m3. It is to be pressurised to 197 msw, with 7 msw of 16%
and 190 msw of 1.5%. What volume of each gas would be needed?
31.5m3 of 16% and 855 m3 of 1.5%
A medical lock is 0.8 metres long and 0.3 metres in diameter. The chamber is at 160 msw. How much
gas is used when the lock is operated?
.905 m3
An equipment lock is 4 ft long and 2 ft 6ins in diameter. The chamber is at 510 fsw. How much
gas is used when the lock is operated?
303.44 ft3
9 divers are in saturation for 5.5 days. How much oxygen will they use in the chamber? (Answer in m.)
35.64 m3
6 divers are in saturation for 12 days. How much oxygen will they use in the chamber? (Answer
in ft.)
1800 ft3
A decompression from 95 msw takes 2 days, with a pO, of 600 mb. There are two divers in the
chamber and the chamber volume is 10 m3. How much oxygen is used?
16.98 m3
Metabolic use:
Oxygen use = 2 x 2 x 0.72 m3
= 2.88 m3
Use during decompression:
Oxygen used = (Ln of the initial absolute pressure) x ppO2
(bar) x chamber volume
Initial pressure = 10.5 bar
Ln (initial pressure) = 2.35 (from calculator)
ppO2 = 0.6 bar
Chamber volume = 10 m3
Oxygen used = 2.35 x 0.6 x 10 m3
= 14.1 m3
Total oxygen use: = (2.88 + 14.1) m3
= 16.98 m3
A decompression from 180 msw takes 4 days, with a pO2 of 600 mb. There are two divers in the
chamber and the chamber volume is 10 m3. How much oxygen is used?
23.4 m3
6 divers are in saturation for a total of 11 days including decompression at 110 msw, with a pO2 of 400
mb. Before starting the decompression, the pO2 is raised to 600 mb. The decompression takes 3 days.
The chamber volume is 15 m3. How much oxygen is used?
72.84 m3
Metabolic use for the whole dive:
Dive time = 8 + 3 = 11
Oxygen use = 6 x 11 x 0.72 = 47.52 m3
Oxygen required to make up the level to 600 mb:
Free gas volume = floodable volume x pressure added
Raising the ppO2 is basically the pressure x volume formula. It is the oxygen added that is
important, not the total volume. The floodable volume is the chamber volume.
Floodable volume = 15 m3
Pressure added = (600 - 400) mb = 200 mb
= 0.2 bar (pressures in bar)
Free gas volume = 15 x 0.2 = 3 m3
Use during decompression:
Oxygen used = (Ln of the initial absolute pressure) x ppO2
x chamber volume
Initial pressure = 12 bar
Ln (initial pressure) = 2.48 (from calculator)
ppO2 = 0.6 bar
Chamber volume = 15 m3
Oxygen used = 2.48 x 0.6 x 15 = 22.32 m3
Total oxygen use = 47.52 + 3 + 22.32
= 72.84 m3
During a saturation, the pO2 in the chamber is maintained at 400 mb. Before starting
decompression, the level is raised to 600 mb. If the chamber volume is 17 m3, what volume of
oxygen is required raise the pO2?
3.4 m3
6 divers are in saturation at 275 fsw for a total of 12 days including decompression with a pO2 of
0.4 ata. The pO2 is raised to 0.6 atm for the decompression which lasts 2 days. The chamber
volume is 500 ft3. How much oxygen is used altogether?
2569 ft3
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?
2 msw
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?
6.2 fsw
Chamber I is at 97 msw, with a pO2 of 400 mb. It is blown down to 130 msw using 2%. What is the
p02 at 130 msw?
466 mb
A chamber is blown down from 180 fsw to 210 fsw using 4%. If the pO2 was 0.4 atm at 180 fsw,
what is it at 210 fsw?
436 ata
After a serious leak, a chamber is at 50 msw with a pO2 of 180 mb. The chamber is blown back
to the living depth of 125 msw using 5%. What is the pO2 at living depth?
555 mb
Chamber I is at 320 fsw, with a pO2 of 0.4 ata, percentage 3.74%. It is bled to 100 fsw. What is the
p02 at 100 fsw?
0.15 ata
A chamber is at 186 msw, with an oxygen percentage of 2.1%. It is bled to 143 msw. What is the
p02 at 143 msw?
321 mb
After equalisation, Chamber I has a volume of 12 m3 and a pO2 of 480 mb. Chamber 2 has a volume of
8 m3 and a pO2 of 400 mb. What is the final pO, when the atmospheres are completely mixed?
448 mb
Chamber | has a volume of 400 ft3 and the pO2 is 0.45 atm. Chamber 2 has the same volume, but
the pO2 is 0.38 atm. What is the final pO2 when the chamber atmospheres are fully mixed?
0.415 ata
Chamber I has a volume of 18 m3 and the pO2 is 420 mb. Chamber 2 has a volume of 12 m3 and
the pO2 is 400 mb. Chamber 3 has a volume of 15 m3 and the pO2 is 600 mb. What is the final
pO2 when all the chamber atmospheres are fully mixed?
474 mb
A chamber and bell are at 185 msw, with a pO2 of 400 mb. For the dive, the bell is separated from the
chamber and blown down on 4% to a working depth of 200 msw. What is the pO2 in the bell at working
depth?
460 mb
Divers are being pressurised in a chamber using 2% straight from the surface. The pressurisation
is aborted at 70 fsw when the oxygen percentage is 8%. The chamber is bled straight back to
surface. What is the pO, on the surface? How do the divers feel about this?
0.08 ata divers unconscious
The bellman uses a chemical sampling tube to take a CO2 reading in the bell. The scale reading is 1.4%.
If the bell is at 400 fsw, give the true percentage of CO2, the pCO2 and the SEP.
True percentage 0.0107 %
PC02 0.014
SEP IS 1.4 %
True percentage = scale reading/ Absolute pressure
Scale reading = 1.4%
Absolute pressure (atm) = depth (fsw)/33 + 1 atm
= 400/33 + 1 atm
= 13.12 ata
True percentage = 1.4%/ 13.12
True percentage = 0.107%
Partial pressure = scale reading/ 100
= 1.4/100
Partial pressure = 0.014 ata
The SEP is simply the scale reading, which is 1.4%
The bellman uses a chemical sampling tube to take a CO2 reading in the bell. The scale reading is
2%. If the bell is at 145 msw, give the true percentage of CO2, the pCO2 and the SEP.
True percentage 0.13%
PC02 20 mb
SEP 2%
A diving bell displaces 5 m3 of sea water and weighs 4.8 tonnes. Is the bell positively buoyant?
Yes by 0.35 tons. Up thrust is 5.15 tonnes
Would the bell in Question 87 be positively buoyant in fresh water?
Yes upthrust is 5 tonnes
A diving bell displaces 180 ft3 of sea water and weighs 5.2 imperial tons. Is the bell positively buoyant?
No upthrust is 5.17 imperial tonnes
A diving bell displaces 180 ft3 of sea water and weighs 5.2 US tons. Is the bell positively buoyant?
Yes upthrust is 5.79 Tonnes (US tonnes = 2000 lbs)
A welding habitat weighs 25 tonnes in air. It displaces 12 m3. What does it weigh in sea water?
12.64 tonnes
A closed length of pipe weighs 12 imperial tons (2240 lbs) and displaces 140 ft3. How many I ton
lifting bags would you need to lift it clear of the seabed? (Ignore suction.)
Lift of 7.98 tonnes = 8 lift bags
What is Boyle’s Law formula?
P1V1 = P2V2
If a wet bell has a floodable volume of 200 ft³ and the air volume is reduced to 20 ft³, what is the depth?
297 fsw
What is the formula for free gas volume?
FGV = FV x P
How do you calculate the usable air in a 45-bottle quad at a pressure of 190 bar?
FV of quad = 45 x 50 x 190 = 427,500 L or 427.5 m³
How much air will a diver breathe in 41 minutes at a depth of 25 msw with a consumption rate of 35 LPM?
5022.5 litres or 5.023 m³
How much air is required to pressurise an 18m³ chamber to 38 msw?
68.4 m³
What is Charles’s Law formula?
P1/T1 = P2/T2
What is the absolute temperature conversion for Celsius?
°C + 273
What pressure is in a bailout bottle charged to 200 bar and cooled from 100°C to 60°C?
178.5 bar gauge
What is the absolute temperature conversion for Fahrenheit?
°F + 460
What does the term ‘free gas volume’ refer to?
The volume that a quantity of gas will occupy at a pressure of 1 bar.
What is Dalton’s Law of Partial Pressures?
States that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each individual gas.
What is the formula for calculating partial pressure?
PP = Dec % x P (where P can be absolute or gauge)
If a chamber is at 30 msw with 19.8% O2, what is the O2 percent at 23 msw?
19.8%
What is the partial pressure of O2 at 23 msw if the decimal percentage is 0.198?
0.653 bar or 653 mbar
What does Henry’s Law state about gas solubility?
The amount of gas that will dissolve in a liquid at a given temperature is almost directly proportional to the partial pressure of the gas.
How does body temperature affect gas solubility according to Henry’s Law?
Lower body temperature results in higher solubility.
If a body absorbs 1 litre of nitrogen at the surface, how much will it absorb at 50 msw?
6 litres
What is Archimedes’ Principle formula?
U = V x D
What is the upthrust of a pontoon measuring 12 m x 7 m x 2.5 m submerged in seawater?
What is the weight of the pontoon if it is floating?
216.3 Tonnes
Equal to the upthrust 216.3 tonnes
How do you convert ppm to percentage?
Divide ppm value by 10,000
