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# Science Of Diving

### SSI course The Science of Diving

Term | Definition |
---|---|

Pressure | Pressure=Force/Area or P=F/A |

Atmospheric Pressure | Air pressure at sea level. expressed as 1 ATA |

Hydrostatic Pressure | The weight exerted by a fluid due to the force of gravity 1 ata=34 feet of fresh water (ffw) 1 ata=33 feet of salt water (fsw) |

Fresh water | exerts 14.7 psi/34 ffw = .432psi/ft |

Salt Water | exerts 14.7 psi/33 fsw = .445psi/ft |

Gauge pressure | pressure does not take in to account atmospheric pressure (mostly for divers information) |

Absolute Pressure | The total pressure exerted on an object Absolute pressure (ata)=Depth (fsw)/(33fsw/ata)+1 |

Formulas for Converting Pressure | Pressure(ata)=(D/33ft) + 1 D=(ata)-1) x 33 ft |

Convert from Celsius to Fahrenheit | F=(C x 1.8) + 32 |

Convert from Fahrenheit to Celsius | C=(F - 32) / 1.8 |

Degrees Kelvin | Degrees Kelvin=C + 273 |

Degrees Rankine | Degrees Rankine = F + 460 |

1 liter | 1000 Cubic centemeters |

1 cubic foot | 1728 cubic inches |

1 cubic yard | 27 cubic feet |

1 statute mile (land) | 5280 feet |

1 nautical mile | 1.151 Statute Miles |

Density | Mass/Volume |

Components of Air | Nitrogen = 78.08% Oxygen = 20.94% Argon = 0.93% Carbon Dioxide = 0.03% Other Gases = 0.02% |

Hypoxia | Not enough O2 to support life at low partial pressures= unconsciousness and death |

Hyperocia | Too much O2 at high partial pressure. = pulmonary ore central nervous system toxicity. |

Pressure | Always referred to as (P) P= (Depth/33) + 1 Depth =(P-1) x 33 |

Boyle's Law | If the temperature remains constant the pressure and volume of any gas are inversely related, ie.. as the pressure increases, the volume decreases and if the volume increases the pressure decreases. |

Boyle's Law formula | P1 x V1 = P2 x V2 |

Charles' Law | If the pressure of a gas is constant, then the volume of the gas varies directly with temperature. |

Charles' Law formula - Constant volume | P1 / T1 = P2 / T2 |

Charles' Law formula - Constant pressure | V1 / T1 = V2 /T2 |

General Gas Law formula | (P1 x V1) / T1 = (P2 x V2) / T2 |

Henry's Law | The amount of gas that will dissolve in a liquid is directly proportional to the partial pressure of that gas, given that the temperature and the molecular movement (agitation) of the liquid are constant |

Dalton's Law | In a mixture of gases, the total pressure (P) of the mixture equals the sum of the partial pressures (pp) of the individual gases. ppgas 1 + ppgas 2 = P |

Dalton's Law formula | ppgas = P x fgas fgas = the fraction of gas in the mixture expressed as a decimal also P = ppgas / fgas |

Buoyancy | is the force by which an object floats or sinks, there are three kinds of buoyancy: |

Neutral Buoyancy | Will remain suspended at the same depth it was placed. |

Negative Buoyancy | Will sink when placed in fluid. |

Positive Buoyancy | Will rise toward the surface, at the surface will remain floating. |

Archimedes' Principle | An object placed in liquid will be buoyed up by a force equal to the weight of the liquid it displaces. |

Archimedes' formula | B = (VO x DL) - WO B = Bouyant force VO = Volume of the object DL = Density of the liquid WO = Weight of the object |

Density of salt water | 64 lbs /cu ft |

Density of fresh water | 62.4 lbs / cu ft |

Surface air Consumption Rate | SAC = (AC / T) / D SAC = Surface air consumption rate AC = Air consumed in psi D = Depth expressed in bar or (fsw /33) =1 T = time |

Formula to find time | T = AC /(SAC x D) |

Formula to find the air Consumed | AC = SAC x D x T |

What changes the appearance of the environment under water | Refraction Diffusion Turbidity Absorption |

Sound | Travels 4x faster in water than it does in air and sound delay is 1/4 that of air so it is hard to determine which way the sound comes from. |

Created by:
nemery12