Chapter 4- Diving Science Diving Science 121 falls, respectively. Because of this change, it is not a good idea to store scuba cylinders in car trunks, which can reach temperatures of over 50°C (122°F). There is little danger from the pressure increase because of heat, but if a cylinder becomes hot enough, it will rupture the burst disk in the valve. Also, if the cylinder repeatedly expands and contracts from the changes in temperature, it will stress the metal and shorten the useful life of the scuba cylinder. It is better to store cylinders with only 7 to 14 bar (100 to 200 psi) of air and fill them just before use than to store them full. The metal alloys from which aluminum cylinders are made will crystallize if subjected to relatively low heat. They should not be placed near fires. If smoke stains are found during the annual visual cylinder inspection, the cylinder cannot be approved for use. Verify What You Have Learned Review the following questions about the thermal effects of diving: 34. You lose most heat under water primarily from water _______________________ and some from warming ________________. 35. Water vapor in air condenses to a liquid when _____________________________. 36. You can prevent a mask from fogging under water by lowering the _______________ of the water. 37. You must drink plenty of fluids when diving to _____________________________. 38. True or False. If the temperature surrounding a rigid container full of gas increases, the pressure of the gas increases.
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