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No.

Years ago, when I took my very first scuba course, the instructors had us walk from the shallow end of a pool to the deep end, wearing a weight belt and breathing through a very long snorkel. Nobody got all the way to the deep end before it became impossible to breathe against the increasing water pressure. It was a very effective exercise in that it taught us very quickly about the effects of ambient water pressure, which doubles in the first 33 feet of sea water.

If the intent of the question is to ask if one can breathe underwater through a garden hose used as a snorkel, the answer is "not deeper than a few feet". In fact, breathing through a snorkel deeper than about two feet is extraordinarily difficult. Your diaphragm simply isn't strong enough to displace the water at deeper depths.

One could use a hose like a garden hose with surface supplied air. The "snuba" systems used at some resorts use this approach. "Scuba", however, is defined as Self Contained Underwater Breathing Apparatus. It's a fair argument that any system which involves a surface gas supply is no longer "self contained".

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Unless you've been specially trained to use any other form of air, it's the same as normal air, just compressed with impurities removed.

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All scuba wetsuits are made out of neoprene which is an elastic synthetic material having great insulation properties. The neoprene itself is impregnated with nitrogen bubbles (neoprene foam) which are not interconnected. This is what contributes to the wetsuit's insulation properties. Because of the nitrogen gas bubbles which are present within the wetsuit's lining, bodily heat loss is further prevented, therefore allowing you to stay warm in colder waters.

Whilst neoprene is a pretty good insulator, one of the properties that make it useful for a wetsuit is that is flexible and can move with the body and be tight fitting. This reduces drag through the water. Although wetsuits are great because they are not bulky, they are not as effective in keeping you warm as dry suits. Dry suits stop you getting wet completely and can be made out of a number of waterproof materials. Originally dry suits were made of oiled canvass and leather and as natural rubbers were developed these were used. Today there are two main types of suit. One is made of neoprene and combines the thermal efficiency of the material and the air gap and clothing to the skin and the other uses a thinner material and largely relies on the thermal undergarments to keep you warm. These suits are called membrane suits and can use a number of rubberised or waterproof materials. Seals to stop water getting in are used at the wrists and neck and are usually made out of either neoprene or latex.

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There are two types of "Diver Down" flags: the well known US version and an international version.

The US version is a rectangular red flag with a single, wide white stripe running diagonally from the top left corner to bottom right corner.

The international "Diver Down" flag is blue and white. It has a vertical white strip with two blue swallow tails. This flag is International Flag Code A (pronounced phonetically as 'alfa' or 'alpha'.) When flown as part of a message, this flag represents the character "A". When this flag is flown independently, it takes on the meaning of the "Diver Down" flag.

Both flags are intended to send the following message to other vessels: "I have a diver down. Keep well clear at slow speed." Check the links for images and specifications.

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It is up for debate, but there are some studies that have shown divers are more likely to get decompression sickness after a plane trip. The thinking is that they become dehydrated on the plane trip - which is a contributing factor to DCI. Another possibility is that the reduction in cabin pressure is enough to generate some small asymptomatic bubbling as the 8,000' cabin pressure may be just past the threshold to cause bubbling.

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No it is not by any means. it is atmospheric air compressed with the high amounts of carbons and other gases lowered or removed.

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Hygv

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Two

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No, even though dental compressors have very clean air, it is still not water-free enough to go in a steel tank, though it shouldn't cause problems in an aluminum, but mainly, even the high pressure dental pumps only go up to 175 psi, and even the lowest pressure scuba tanks are 2400psi, going up to 3300 in North America and 5000 in Europe.

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5 bars = 40 meters if you are looking to buy a watch you would not be able to take this one scuba diving but you would be fine in the bath tub
50 metres H2O 164.0 ft H2O 4.903 bar

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Diving, using trapped/contained ambient pressure air with no air-supply connection to the surface, likely began many centuries ago. With enough weight to counteract the buoyancy of the trapped air, almost anything is possible, and was probably attempted. Breath-hold or 'free' diving's origins, however, can be traced back to several thousand years BC, most likely attempts to salvage sunken treasure from wrecked ships. Both commercially and recreationally, free diving is still, by far, the most common and frequent. Cheapest, too. Strictly speaking, however, Self-Contained Underwater Breathing Apparatus, or SCUBA, using pressurized (150 atmospheres/approx 5300(!!!)lbs) air with a downstream user-demand regulator valve can be very closely dated. In his (highly reccomended) 1953 book, "The Silent World", Capitaine Jacques-Yves Cousteau describes how, in June, 1943, he first tested (his own design of) the world's first (23kg) 'aqualung', accompanied by Phillipe Taillez as (surface) dive-boat 'tender' and Frederic "Didi" Dumas as 'safety' (skin) chase diver. Capitaine Cousteau's wife, Simone was to observe only, using mask and schnorkle.

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The pressure increase is dependent on density of the water. Pure water at 60F has about 27.78 inches of water column (INWC or INWG) per psi or approximately 0.43197 psi/ft. This is from memory; but it should be close.

Fresh water: 0.43 psi per foot Sea water: 0.44 psi per foot.

So, for each additional 10 feet of depth, figure about 4.3 to 4.4 psi increase in pressure.

You can calculate this yourself by using the fact that fresh water weighs about 62.4 pounds per cubic foot (pcf) and sea water weighs about 64 pcf. Divide those numbers by 144 (the "footprint" of one cubic foot, 12 x 12) and there you go.

It's interesting to note that this pressure is independent of volume or expanse. i.e. the water pressure behind a fresh water dam at 100 feet deep is about 43.3 psi regardless of whether the dam's reservoir is 25 miles long or 10 feet long. Depth and density are the only relevant parameters needed to determine pressure.

Dive pressure, however, would be the water pressure of 43.3 plus the air pressure above the water. So the net pressure on your ears & body would be 43.3 plus 14.7 (one atmosphere)totalling 58 psi,or about 4 atmosphers. That's four times our normal experience. Worthy of careful consideration.

Regarding diving - internal pressure inside ones body EQUALS the atmospheric pressure (14.7 psi). [Otherwise we would be squashed by the athmospere.]

Therefore, the net result is still dependent on depth ONLY - in example given it would be around 2.95 atmospheres.

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Frankly, speaking to all of you what i had been told by one of the saturation diver that the maximum age doesn't matter atAl's long our medical is pass and fit. Because some of the saturation divers in UK overthrow their ages is 65 years old there still doing the saturation diving. As long you all who get involve in saturation diving operation is fit for your medical fitness you can still continue the job. Kathi's is what i can share the information to all of you.

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The qustion should be rephrased to "What is the DENSITY of air at 15 psi." Volume is independent of mass, i.e. one cubic foot is one cubic foot regardless of pressure. Density refers to how much mass there is per unit volume. At 15 psi or, more accurately 14.7 psi, (atmospheric pressure at sea level) the density of air is 0.0805 pounds per cubic foot (pcf). Not much. This is commonly called one "atmosphere." Compare that with 62.4 pcf for fresh water and about 64 pcf for sea water. I ran some quick numbers and found that for each 33 feet of sea water depth the pressure increases by one atmosphere (14.7 psi.) The common recreational dive depth limit of 60 feet corresponds to just under 3 atmospheres, including 27 psi water pressure plus 14.7 air pressure above the water for a total of about 42 psi.

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1cu ft = 12 * 12 * 12 cu.in = 1728 cu in = 1728 * (2.54*2.54*2.54) cc = 28316.85 cc = 28.3 liters = 28 kg or 62.4 pounds

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It's just barely possible you could under the right conditions. You'd need to be quite close to the submarine, and they'd be distorted and difficult to understand, the same way you can hear your neighbors in an apartment building but not necessarily be able to understand what they're saying. It doesn't seem likely you could hear conversational voices; they'd probably have to be shouting.

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sharks generally do not care that much for human blood.. now put a few drops of fish blood in the water and that is a different story...

For what it's worth..."There is no evidence of increased shark interest in a menstruating female. The hemolytic blood associated with menses may instead act as a shark deterrent (Edmonds, et al., 1992, p. 65)."

I found the following reference particularly helpful. It is on the Divers' Alert Network and is titled, "Diving Medicine FAQs, Menstruation During Diving Activities"

http://www.diversalertnetwork.org/medical/faq/faq.asp?faqid=109

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Approx $1500 - $2000