Techniques and Procedures I RC 170

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Techniques and Procedures IRC 170

• Basic Physics
• For
• Respiratory Therapist

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Energy

• Energy- the ability to do work
• Work force X distance
• Kinetic energy- energy that an object possesses
  when it is in motion.
• Potential energy or stored energy- the energy an
  object possesses because of its position. (energy
  of position, gravitaxl)

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Matter has mass and occupies space

• Atomic Theory all matter is composed of tiny
  particles called atoms.

• Kinetic Theory atoms and molecules that make up
  matter are in constant motion

Figure 1-1 States of Matter
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States of Matter

• Solid
• Limited atomic motion due to Van der Walls forces
  (mutual attracx)
• Mostly Potential Energy, very little Kinetic
• Hard to compress
• Liquid
• Freedom of motion - Some KE
  some PE
• Takes shape of container
• Exhibits flow
• Hard to compress
• Gas
• very weak attractive forces - mostly KE
• Lacks Motion restrictions
• Able to Flow, expand/compress

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Temp and Pressure scales

• Temp conversions Box 1-3, page 9
• Pressure conversions Box 1-4, page 9
• 1 ATM 760 mmHg 14.7 psi 1034 cmH2O
• 1mmHg 1.36 cmH2O

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Temp Scales
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1st Law of Thermodynamics

• Energy can be neither created nor destroyed, only
  xformed in nature
• Energy gains must energy losses
• Equal energy requirements to freeze/melt

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Change of State
Boiling point temperature at which a liquid
converts to a gaseous state
Figure 1-3 Temperature Scales
Freezing point temperature at which change
occurs from a liquid to a solid
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The relationship between temperature, pressure,
and kinetic activity of water molecules.
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Critical Pressure/Temp

• Critical Temperature T at which a gas cant be
  converted back to a liquid state at any pressure
  (-118 C 182 F for O2)
• Critical Pressure P required to convert a gas
  back to a liquid state at its critical
  temperature (716 psi for O2)
• Gas state of matter above it critical
  temperature
• Vapor state of matter below its critical
  temperature

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Change of State

• Evaporation Change from Liquid to Gas Below its
  boiling point
• Rate of evaporation increases with
• ? temperature, ?surface area
• ? PB
• Sublimation Change from solid to gas by-passing
  the liquid state
• Condensation conversion of a substance from a
  gas to a liquid.

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Heat Xfer

• 1st law tells us that 2 objects of differing
  temps will xfer energy (Heat) until at
  equilibrium
• 4 modes of heat xfer
• Conduction (direct contact, solids)
• Convection (direct contact, fluids)
• Radiation (indirect contact)
• Evaporation/Condensation
• energy is xferd due to change of state
• Evaporative cooling

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Hg Barometer
Figure 1-4 A mercury barometer
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Aneroid Barometer
Figure 1-5 An aneroid barometer
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Electronic Transducer
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Pressure and Humidity

• Water Vapor Pressure P exerted by vapor due to
  kinetic activity which is T dependent. (Table 1-4
  page 16)
• _at_ 37C 47 mmHg of VP
• Absolute Humidity actual content of water
  present in a sample of gas.
• Relative Humidity actual content of water
  present in a sample of gas relative to its total
  carrying capacity. Expressed in a .
• (Page 103 Egan Table 6-3)

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BH Humidity Deficit

• Body Humidity ratio of water vapor capacity
  at body Temp. (37C)
• Humidity Deficit
• The difference b/w capacity content
• Absolute Humidity at Body Temp
• 43.8 mg/L

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Properties of Liquids

• Pascals Principle
• A Liquids Pressure is exerted in all directions
• Pressure exerted depends on Depth (height)
  Density
• Viscosity
• Opposing Force to a liquids flow
• Directly proportional to molecular cohesive
  forces
• Increased Temp decreases viscosity
• Weakens molecular bonds

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Properties of Liquids
Figure 1-6 A practical example of buoyancy.
Archimedess Principle when an object is
submerged in a fluid, it will be buoyed up by a
force equal to the weight of the fluid that is
displaced by the objectif the weight density
of the object being submerged is less than the
weight density of the water, the object will
float
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Properties of Liquids
Adhesion Cohesion
Water Meniscus (Adhesion)
Mercury Meniscus (Cohesion)
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Properties of Liquids
Figure 1-8 The molecular basis for surface tension
Surface Tension cohesive forces between liquid
molecules at a gas- liquid interface. Box
1-5 Adhesive and Cohesive forces.
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Properties of Liquids
Laplace's Law the pressure within a sphere is
directly related to the surface tension of the
liquid and inversely related to the radius of the
sphere
Surface Tension forces cause a liquid to have the
tendency to occupy the smallest possible area,
which is usually a sphere.
Figure 1-9 Laplace's law.
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Properties of Liquids
Capillary Action
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H20 DVD VIDEO MODERN MARVELS PART I
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Gas Laws

• Boyles The volume that a gas occupies when it
  is maintained at a constant temperature is
  inversely proportional to the absolute pressure
  exerted upon it.
• With a constant temperature
• If you double the Press, your volume halves
• As press increases, Volume decreases vice versa
• P1V1 P2V2 P1V1 P2V2

T1 T2
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Boyles Law
Figure 1-10 Boyles Law
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BOYLES ON YOU TUBE
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Boyles Law

• Joule-Thompson Effect
• Expansion Cooling
• Purging a cylinder
• Due to breaking of van der waals bonds
• Compression Heating
• Diesel engine

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Gas Laws

• Charless When the pressure of a gas is held
  constant, the volume of a gas varies directly
  with its absolute temperature
• Under Constant pressure
• Increase in temperature will increase the volume
• V1 V2
• T1 T2

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Charless law
Figure 1-11 Charles's law
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CHARLES ON YOU TUBE
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Gay-Lussacs law

• Gay-Lussacs if the volume of a gas is held
  constant, the gas pressure rises as the absolute
  temperature of the gas increases.
• Volume is constant
• Pressure increases as temperature increases
• P1 P2
• T1 T2

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Gay-Lussacs law
Figure 1-12 Gay-Lussacs law
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GAY-LUSSAC ON YOUTUBE
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Combined Gas Law
Combined Gas Law
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Daltons law of Partial pressures

• The sum of the partial pressures of a gas mixture
  equals the total pressure of the system.
  PB 760 mm Hg
• PO2 (760) (0.21) PO2 159 mm Hg
• PB PO2 PN2 PCO2 P (trace gases)
• PB (760)(0.21) (760)(0.78) (760)(.003)
  (760)(.07)
• PB 760 mm Hg

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Laws of Diffusion

• Diffusion net movement of gas molecules from a
  high concentration to a lower concentration.
• Grahams Law The lower the density of the gas
  the more diffusible the gas.
• Henrys Law The higher the partial pressure of a
  gas the quicker it will dissolve in a liquid.

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Ficks law of Diffusion

• Ficks the rate of diffusion of a gas in a
  gaseous medium is proportional to the gradient of
  their concentration, the surface area available
  for diffusion, and inversely proportional to the
  thickness of the membrane.
• The higher the concentration of the gas the
  quicker it dissolves.

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Ficks law of diffusion
Figure 1-14 Ficks law of diffusion
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Pre-class Survey!

• In mmHg, what is the pressure exerted by water in
  air _at_ 37C?
• In mg/L, What is the absolute content of water
  vapor in air _at_ 37C?
• What is the Cylinder Color for Oxygen?
• What is the Cylinder factor of an E tank?

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Fluid Mechanics

• Laminar flow smooth flow page 18 fig.1-5
• Viscosity of the gas
• Length of the tubing
• Radius of the tube
• Turbulent flow rough flow chaotic disorderly
  pattern or layers. ?velocity
• Transitional flow mixture of laminar and
  turbulent flows.

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Figure 1-15 Three patterns of flow laminar,
turbulent, and transitional
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Poiseuilles Law (Laminar flow)

• Driving pressure plus resistance to flow
• Viscosity of the fluid/gas
• More viscous the greater the pressure needed
• Length of the tube
• Longer the tube greater the pressure needed
• Radius of the tube (4th power of the radius)
• ? radius by ½ will ? resistance by 16 times
• Smaller the radius the greater the pressure
  needed
• Reynoldss number Turbulent flow occurs when
  Reynoldss number exceeds 2000.

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• Modern Marvels Part II

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Press in flowing fluids

• STATIC FLOWING

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Bernoulli Principle

• Bernoullis as the forward velocity of a gas
  (or Liquid) moving through a tube increases, the
  lateral wall pressure of the tube will decrease.
• Drop in lateral fluid pressure is directly
  related to the increase in fluid velocity.
• Law of Continuity fluids velocity varies
  inversely with x-sectional area

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Figure 1-16 The Bernoulli principle
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Venturi Principle

• The lateral pressure drop that occurs as the
  fluid flows through a constriction in a tube can
  be restored to the pre-constriction pressure if
  there is a gradual dilation in the tube distal to
  the constriction.
• This also helps to prevent turbulent flow.

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Entrainment port
Figure 1-17 The Venturi principle
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Entrainment
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Air Injector
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Coanda Effect

• Coanda Effect wall attachment phenomenon
• A wall placed next to a jet stream of gas creates
  a low-pressure vortex or separation bubble. The
  gas stream tends to bend towards the wall. (Page
  332 figure 11-21)

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Figure 1-18 The Coanda effect