MEDICAL GASES
Manufacture, Storage, Transport
+ Delivery
First Year Respiratory Therapy
MJC
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Composition of the Air

We breathe earth’s atmosphere composed
of:




Nitrogen (78%)
Oxygen (21%)
Carbon Dioxide (0.03%)
Argon and trace gases (0.93%)

Neon, Xenon, Krypton and Deon
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How Oxygen is produced
Fractional Distillation
Physical Separation
Nitrogen Molecular sieve
Semi-Permeable membrane
Fractional Distillation
Large Manufacturing Facility
Fractional
Distillation for
liquid O2
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Fractional Distillation



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Atmospheric air is filtered of pollutants,
carbon dioxide and water
Air is compressed and cooled to a liquid
Then it is slowly heated and the nitrogen boils
off.
Liquid oxygen remains
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Physical Separation
Molecular Sieve
Semi-Permeable Plastic Membrane
(in the home)
Molecular Sieve



Composed of inorganic sodium aluminum
silicate pellets
These pellets absorb the nitrogen and water
vapor from the air
Produces up to 90% mixture
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Oxygen Concentrator
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Semipermeable Membrane




Pulls air through membrane
Oxygen passes through faster than nitrogen
Can produce 40% mixture
Good for long-term low flow oxygen
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Oxygen concentrator–Semi-permeable membrane
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Physical Separators


Will produce concentrations for nasal cannula
but only at low flows
Used in oxygen concentrators IN THE HOME
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Home Concentrator
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Medical Gases
Oxygen, Carbon Dioxide, Helium,
Nitrous Oxide, Nitric Oxide, Nitrogen,
Carbon Monoxide
Properties of Common Gases

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Chemical symbol
Molecular weight
Color, odor, taste
Physical state


Critical temperature, boiling point
Combustion characteristics
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Oxygen




02
Molecular Weight 32
Colorless, odorless, tasteless
Slightly heavier than air


Density of 1.29 g/L
Nonflammable but supports combustion
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Compressed Air




Is the same mixture of nitrogen, oxygen,
carbon dioxide and argon.
Is piped in to all modern hospitals
Used to power pneumatically powered
equipment
Some situations (patients are C02 retainers)
when oxygen is contraindicated
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Carbon Dioxide



C02
Colorless and Odorless
Does not support combustion


More soluble in liquids than oxygen


Used in fire extinguishers
Easier transporting in blood then oxygen
Used to treat hiccups (singulation)
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Helium

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

He
Odorless, tasteless, non-flammable
Second lightest of gases
Combined with oxygen (heliox) to reduce
work of breathing with swollen upper airways
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Nitrous Oxide




N 20
Nonflammable but supports combustion
Used as an anesthesia in OR (laughing gas)
Always mixed with oxygen (Entonox) and
other anesthesia agents
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Nitric Oxide




N0
Is nonflammable but supports combustion
Used experimentally in low concentrations
(ppm) for pulmonary vasodilation
Recently has had excellent results with
premature babies
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Nitrogen


N2
Used as lab gas (liquid) for freezing tissue
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Carbon Monoxide



CO
Used in Pulmonary Function Lab
Very diffusible – used to test how easily gas
will pass through the lung membranes
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Cyclopropane

Strictly an anesthesia gas
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Ethylene Oxide


Used to gas sterilize medical equipment
Useful for equipment that can’t handle high
temperatures or immersion in water
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Oxygen Storage
Tanks – Liquid
Tanks - Gas
Tank Sizes and Capacities
Large Cylinders
Small Cylinders
Oxygen Tank Sizes
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H Cylinders


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
2200 psi
A.S.S.S safety system
Threaded connection
Need to be safety chained and in a secured
dolly for moving
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E Cylinders



Small and lightweight (15 pounds)
PISS – Pin Index
Yoke connection
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Types and colors of cylinders
Air
Yellow
 Oxygen Green – Int’l (White)
 Helium Brown
 CO2
Grey
 Nitrogen Black
 Nitrous Oxide-Blue
Do NOT trust the color of the tank as sole
indicator of it’s contents

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Labels –
The only
sure way
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Other Oxygen Tank Markings
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Regulation of cylinders
D.O.T
O.S.H.A.
F.D.A.
B.M.D.
Recommending Agencies




C.G.A.
N.F. P.A.
A.N.S.I.
I.S.O
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Bulk Supply Systems
Liquid Oxygen
Bulk Oxygen Systems

Large capacity


Liquid oxygen
Small system (or back up)


Nitrous Oxide
Bank of H cylinders
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Large Oxygen Supply System
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Small Bank of Cylinders
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Liquid vs Gas

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Insulated – Liquid
Solid metal - Gas
Large continuous demand – Liquid
Small portable – Liquid or tank
Tanks act differently if they contain gas or
liquid

No accurate gauge on liquid tank content
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Go figure
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Liquid Oxygen





Constantly losing oxygen despite insulation
Needs pressure and insulation for cold
temperature (-118oC)
Low pressure (200 psi)
Large system has vaporizers fins to help with
heat transfer when liquid turns to gas (frozen
year round)
Small system is great for mall shopping
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Bulk
Liquid
Oxygen
supply
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Bulk
Oxygen
Supply
System
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Home Liquid
Oxygen
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Low Pressure Safety Systems
Diameter Index Safety System
Quick Connect
Wall (low pressure) systems

D.I.S.S.



50 P.S.I
The MJC lab has these
Quick connect

A newer “better system”
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DISS (and
Dat)
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DISS Wall Outlet
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Different Quick Connects
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More Quick Connects
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Flowmeters


Thorpe Tube is most common
Can use Bourdon Gauge
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Other Safety Features
Zone Valves
Zone Valve System
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Zone Valves
for bulk O2
supply
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Cylinder Connections
(High Pressure)
American Standard Safety System
Pin Index Safety System
Key Index Safety System
Regulators



They decrease internal tank pressure down
to a working pressure (50psi)
They read and display the internal tank
pressure
They meter out the precise flow for patient
use.
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Cylinder connections

A.S.S.S. (American Standard)



H cylinders
High pressure, large tanks
P.I.S.S. (Pin Index)


E cylinders
High pressure, small tanks
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American Safety Standard System
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Pin Index System
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Pin Index System
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Pin Index
Numbering
for small
cylinders
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Tank Duration
How long will they last
Cylinder Duration Calculations

You can memorize size of tank then calculate
how long it will last
Or use:
 Conversion factors


3.14 for H cylinders
0.28 for E cylinders
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Liquid Oxygen Duration




Convert pounds to liters
Multiply by 860 to get volume of gaseous
oxygen (Liters)
Divide by the liter flow (L/min)
Convert minutes to hours and minutes
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Thanks for listening
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