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87 Cards in this Set
- Front
- Back
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Charles Law
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When pressure is constant, temperature and volume have a directly proportional relationship
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Boyle's Law
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When Temperature is constant, pressure and volume have an inverse relationship
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Gay Lussac's Law
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When Volume is constant, temperature and pressure have a directly proportional relationship
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Dalton's Law
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The total pressure of a system is equal to the sum of it's component gases; each gas contributes it's percent of the total mixture
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Standard Pressure
standard Temperature |
760 mm Hg
O Celsius |
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Joule Thompson Effect
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Rapid expansion of a gas (increasing the volume) has a cooling effect, and can cause frosting on canisters
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Poisuelle's Law
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Flow is affected by pressure gradient, viscosity, length of tubing, but most dramatically by changes in radius (to the 4th power)
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Law of Laplace (cylinder)
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When the diameter of a cylinder increases, the tension in the wall of the container increases (aneurysms, LV)
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Law of Laplace (sphere)
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The smaller the diameter, the higher the pressure within the sphere and higher tension on wall; increasing the diameter decreases the pressure and tension
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Bernoulli's Principle
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When there is narrowing/ constriction in a tube, it results in increased velocity and decreased pressure at the area of narrowing
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Venturi Effect
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The application of Bernoulli's Principle: Substances can be entrained and carried forward by low pressure area following a constriction in a tube (MDI, Venturi mask)
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Adiabatic changes
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Rapidly compressing a gas causes an increase in temperature, rapidly decompressing a gas results in a lower temperature (no time to equilibrate)
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Ideal gas law
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PV= nrT
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Henry's law
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At a constant temperature, the amount of gas dissolved in a liquid is directly proportional to the partial pressure of gas over the liquid
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Diffusion hypoxia
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N20 has a higher molecular weight than O2, so it diffuses more slowly. When gases are turned off, if low O2 is provided, a hypoxic mix can result within the alveoli as N2O takes the available space for O2, and this decreases the driving pressure of oxygen into the bloodstream
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Latent heat of vaporization
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The amount of energy needed to transform a given amount of liquid into a gas
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Fick's Law
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5 factors affect diffusion: concentration gradient, tissue area, fluid tissue solubility are proportional, membrane thickness and molecular weight are inversely proportional
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Reynold's Number
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Predicts when flow will become turbulent (if number greater than 2000), flow becomes turbulent if velocity is too high, rough walls, bends or kinks, or flows through an orifice, radius changes, viscosity, and density
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Avagadro's number
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One mole of gas contains 6.023 x 10^23 molecules; one mole of gas at STP occupies 22.4 L
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Second gas effect
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Because different gases have different blood gas solubilities, it could happen that one gas is absorbed much more readily from the alveoli into the blood, causing the gases remaining within the alveoli to become more "concentrated" following the efflux of nitrous which is very soluble in blood
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Which is more soluble in blood: O2 or N2O?
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N2O is 20 times more soluble in blood than O2
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When can equilibration of inhalation agents be said to have taken place?
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When the concentration of agent is the same in all tissues
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Upon who's law is the pulse oximeter founded?
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Beer's law: describes how intensity of light is altered as it flows through a liuid
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Vapor Pressure
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The pressure at the boiling point: molecular transfer of particles from liquid to gas is in equilibrium and the vapor above the liquid is saturated
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gas bubbles in IV tubing following warming of liquid is a demonstration of who's law?
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Henry's Law
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How do you determine the liters of gas left in an O2 cylinder?
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multiply psi x 0.3
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Brownian Movements
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Random movement of particles of gas due to collisions, influenced by temperature
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Finding L of gas remaining in a cylinder
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Weigh cylinder and subtract tare weight; convert kg to g, divide the grams of gas by the molecular weight in grams, and multiply by 22.4
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One mole of gas =
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22.4 L,
also equals its molecular weight in grams |
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Graham's Law
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Smaller molecular weight substances diffuse more easily/ faster
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What problems are associated with N2O use during anesthetic administration?
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N2O will follow its concentration gradient into all air filled spaces, making them larger (i.e. increase size of pneumothorax, ETT cuff)
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Why does Helium administration help in cases of turbulent flow?
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Low molecular density equals decreased resistance and better flow
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Resistance due to viscosity can be overcome by:
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Increased pressure, increased energy (heat); think of fast blood administration (decrease viscosity by adding NS, warm the blood, and put it on a pressure bag)
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Coanda effect
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If a tube branches following a constriction in the tube, flow will go down one limb of the branch versus dividing equally between the two (example of coronary arteries following area of narrowing, bronchial narrowing and subsequent maldistribution of flow)
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Property of a fluid that determines flow when flow is laminar
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viscosity
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Degree angle at which laminar flow will become turbulent
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25
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Resistance to flow Increases or decreases when flow becomes turbulent?
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increases (i.e. airway pressures will increase if flow through ETT is turbulent d/t secretions, kinks, etc)
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Formula for applying Henry's Law to plasma concentration of O2 and CO2
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0.003/100 ml blood/ mm Hg partial pressure- multiply the partial pressure of O2 x 0.003, or for CO2 multiply by 0.067
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O2 and N20 psi and liters
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O2- 2200 psi and 660 L,
N20 745 psi (until all in gaseous state at which point it drops precipitously), 1590 liters |
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1 mmHg = ? cm H2O
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1.36 cm H2O
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1 atm = ? mm Hg (at sea level, STP)
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760 mm Hg
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Critical Temperature
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Temperature above which a gas cannot be maintained in a liquid state, regardless of pressure
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Critical Pressure
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pressure required to liquefy a gas at its critical temperature
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Safety devices to regulate pressure of cylinders due to changes in temperaute
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Frangible disc ruptures under pressure (overfilling or increased temp), wood's metal melts and releases gas in controlled fashion at excessive temperatures
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PISS
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Pin index safety system (for cylinders)
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DISS
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Diameter index safety system (for hoses)
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High Pressure system of gas machine
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Gas cylinders, yokes
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Intermediate pressure zone of gas machine
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Primary regulator on cylinders to Seondary regulator; pipeline supply, standby switch, O2 flush button
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Low pressure zone of gas machine
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Flow meters (balance regulator, fail safe), vaporizers,
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Who regulates the purity of medical gases?
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The FDA
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Who regulates the manufacturing, marking, labeling, filling, qualification, transportation, storage, handling, maintenance, requalification, and disposition of medical gas cylinders?
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The DOT
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Who regulates the safety of medical as cylinders?
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OSHA
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Constituent metals of wood's metal?
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Bismuth, tin, cadmium, lead (Boy these cylinders leak)
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Pressure relief valves
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Resealable, spring loaded, useful up to 500 psi
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Who regulates the purity of medical gases?
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The FDA
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Who regulates the manufacturing, marking, labeling, filling, qualification, transportation, storage, handling, maintenance, requalification, and disposition of medical gas cylinders?
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The DOT
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Who regulates the safety of medical as cylinders?
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OSHA
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Constituent metals of wood's metal?
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Bismuth, tin, cadmium, lead (Boy these cylinders leak)
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Pressure relief valves
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Resealable, spring loaded, useful up to 500 psi
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Markings on cylinders
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tare weight, test pressure, retest date, manufacturer's stamp, color, volume
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Do not expose cylinders to temperatures above:
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125 degrees F
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Safety considerations for storing cylinders;
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Do not expose them to combustibles (grease, dust, etc), keep valve closed when not in use,
proper securement, do not create oxygen rich environment (draping patient then using cautery) |
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Identify gas cylinders by:
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multiple means: color, label
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Do not use cylinder if:
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PSIG is greater than service pressure
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Markings on cylinders
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tare weight, test pressure, retest date, manufacturer's stamp, color, volume
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Markings on cylinders
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tare weight, test pressure, retest date, manufacturer's stamp, color, volume
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Do not expose cylinders to temperatures above:
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125 degrees F
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Do not expose cylinders to temperatures above:
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125 degrees F
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Safety considerations for storing cylinders;
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Do not expose them to combustibles (grease, dust, etc), keep valve closed when not in use,
proper securement, do not create oxygen rich environment (draping patient then using cautery) |
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Safety considerations for storing cylinders;
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Do not expose them to combustibles (grease, dust, etc), keep valve closed when not in use,
proper securement, do not create oxygen rich environment (draping patient then using cautery) |
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Identify gas cylinders by:
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multiple means: color, label
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Identify gas cylinders by:
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multiple means: color, label
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Do not use cylinder if:
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PSIG is greater than service pressure
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Do not use cylinder if:
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PSIG is greater than service pressure
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The ONLY way to know the volume left remaining in a N2O tank (or other liquid gas)
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Weigh the cylinder, subtract the tare weigt, convert weight to grams, divide by the molecular weight of the gas, and multiply by 22.4
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Why does altitude sickness occur?
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There is less oxygen in the atmosphere at higher elevations, so less oxygen available in alveoli, and less of a concentration gradient to "push" oxygen into blood
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Shut off "zone" valves for medical gases
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Quarter turn valves, should locate in the OR
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Minimum flow
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Varies from machine to machine, but typically 150-250 ml/min
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+ sign on O2 tank
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You can overfill the tank to 110%
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Shut off valve
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Near outlet source, also valve near bulk supply somewhere in the
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Nitrous "secondary regulator"
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Does not exist; the balance regulator down regulates the pressure of N2O at that diaphragm
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Fail Safe
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Intermediate pressure system
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Pin Index Safety System
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Each gas has a pin in position 5, Air has pin in position 1, O2 has pin in position 2, N20 has pin in position 3
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Viscosity
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The attraction caused by the friction between the molecules of a flowing substance
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Solubility
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The maximum amount of one substance that can dissolve in another- influenced by temperature, intermolecular interactions, and pressure
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Diffusion
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net movement by random motion that minimizes a concentration gradient
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At a given pressure, temperature at which a liquid will convert to a gas
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Boiling point
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