l39parts(at)hotmail.com
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 Posted: Sat Mar 31, 2007 4:06 pm Post subject: Footnote RE: CGA standards....Compressed Gas Assoc....R |
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SCUBA cylinders, which many people use for filling Eastern block air
systems, come in all colors.
| Quote: | From: Craig Schneider <craig(at)ustek.com>
Reply-To: yak-list(at)matronics.com
To: <yak-list(at)matronics.com>
Subject: CGA standards....Compressed Gas Assoc....RE: Oxygen
Date: Sat, 31 Mar 2007 15:43:12 -0400
CGA Standards
PRODUCTION, STORAGE AND DELIVERY OF GASES
Gases and Symbols
Oxygen 02
Nitrogen N2
Helium He
Ethylene C2H4
Carbon Dioxide C02
Nitrous Oxide N20
Cyclopropane (CH2)3
Common Mixtures
Oxygen/Nitrogen 21%02: 79% N2
Oxygen/ Carbon Dioxide (no more than 10% CO2)
Helium/ Oxygen (Oxygen (at) 21-60% with the remainder Helium) Referred to as
"Heliox"
Gas Hazards
Ethylene and Cyclopropane readily burn (flammable)
Gases Which Support Combustion
Oxygen
Helium/Oxygen
Oxygen/C02
Oxygen/ Nitrogen
Nitrous Oxide
Non-Flammable Gases
Nitrogen
Carbon Dioxide
Helium
Production
Fractional Distillation
Compress Air ( 100 Atm)
Cooled to liquid state
Rewarm to critical temp of each specific gas
Draw off each gas at critical temp.
Standards of Purity
Set by the FDA
Example: Oxygen must be >99% pure for medical use
(In comparison: industrial oxygen for welding much lower)
OXYGEN
Colorless
Odorless
Tasteless
Transparent
Density: 1.43 g/L (at) 0oC and 1 atm
Boils (at) -183o
Most abundant element in Earth crust
Compressed Air
Air contains all the gases of our natural atmosphere
Provided by tanks or through piping systems from compressors within the
hospital
Carefully filtered and provided oil free
Used as oxygen dilutant or as propellant
Carbon Dioxide: CO2
Colorless
Odorless
1 1/2 x heavier than air
FDA purity standard 99.9%
Helium
Second lightest element ( low density)
Odorless
Tasteless
Inert
Used therapeutically as Heliox for airway obstruction ( Will pass through
smaller spaces than air or pure 02)
Nitrous Oxide: N2O
Colorless
Faintly sweet smell
Anesthetic agent
Must be blended properly with oxygen and usually combined with other
anesthetics
CYLINDERS
Cylinders
Commonly referred to as "tanks"
Provide a way to contain separate gases and transport them
Seamlessly constructed
Steel alloy - often chrome-molybdenum
Made by spinning or stamping in a single piece
Cylinders Con't
Special markings on "shoulders" to designate:
DOT specified materials
Example: 3AA: seamless, high strength, heat treated alloy
Service Pressure: 2015 psi Serial # for that cylinder
Manufacturer's mark
Owner's Mark
Reverse side: Hydrostatic testing date
Inspectors mark
Retest date(s) : star indicates 10 yr cycle
Cylinder Sizes
Medical cylinders are typically E used for transport, 22 cu. ft gas, 4 1/2"
in diameter and 30" tall.
there are 28.3 liters in each cubic ft.
Cylinder Sizes
H/K
contains 244 cu. ft. 9 in. diameter and 55 in. high used for home care or
running equipment
Identify Cylinder Gas By:
LABEL! Required by FDA
USP sets purity standards
Color code: set by Compressed Gas Association (CGA)
Cylinder Codes
Oxygen - green
CO2 - gray
Nitrous oxide - light blue
Cyclopropane - orange
Helium - brown
CO2/ O2 - gray/green
Helium/O2 - brown/green
Air - yellow or green/black
Ethylene - red
Cylinder Pressure Safety System
Full assumed 2200 psi ( E,H,K,M)
Safety valve E: fusible plug, melts (at) 150-170oF
Safety valve H: frangible disk, ruptures (at) 5% below max test pressure
Storage Guidelines
Stored according to NFPA
Secured, no movement, safety signs posted, no smoking signs
Dry, Cool, Well ventilated
Anesthetics stored separately away from oxygen
Cylinder Valve Safety System
Similar sized cylinders can contain dissimilar gases. To avoid misuse:
CGA developed special valve attachments
E and smaller:Pin Index Safety System
Larger than E: American Standard Safety System
Pin Index Safety System
Specific placement of TWO holes drilled into valve stem. Placement defines
which gas in cylinder Paired #s for each Example: 2-5 Oxygen, 1-5 Air, 3-5
N2O
American Standard System
Threaded connections which vary in thread number and thread angle
Connectors will not thread onto dissimilar gases.
REGULATORS
Two sections:
1) Reducing valve: allows 2200 psi to be reduced to a safe pressure of 50
psi
2) A flow device
E or smaller, YOKE style
Larger than E, threaded regulators
Read pressure within tank off regulator pressure gauge
Pressure Gauge Readings
Open the valve of the tank and read the pressure on the gauge
Full should be 2200
Use conversion factor to find out how many liters of gas available
Conversion Factors
E factor: 0.28 L/psi
Example: 1000 psi x 0.28 = 280 Liters
H factor: 3.14 L/psi
Example: 1000 psi x 3.14 = 3140 Liters
The difference occurs because the tanks are very different in volume
Recall E is 22 ft3, H is 244 ft3
TANK DURATION FORMULA
minutes = pressure x factor
flowrate
EXAMPLE
minutes = 2200 psi x 0.28 L/psi
5 L/min
min. = 616 L = 123
5 L/min
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