Med gas 1

Compressed Gas Association (CGA)

Sets standards and safety guidelines for manufacturing, transporting, and storing compressed gases.

National Fire Protection Association (NFPA)

Creates standards for storage of flammable and oxidizing gases.

Department of Transportation (DOT)

Regulates cylinder construction, testing, and transportation.

Food and Drug Administration (FDA)

Sets purity standards for medical gases

Bureau of Medical Devices (BMD)

Provides standards and regulates medical devices.

Occupational Safety & Health Administration (OSHA)

Ensures safe working conditions for employees.

Flammable Gas Definition

Explosive when mixed with air or oxygen in the right proportions.

Non‑Flammable Gas Definition

Not easily ignited and does not burn rapidly if ignited.

Examples of Non‑Flammable Gases

Nitrogen (N₂), Carbon dioxide (CO₂), Helium (He).

Combustion Definition

Rapid chemical reaction with oxygen that releases heat.

Gases that Support Combustion

Oxygen, Nitric Oxide, Compressed Air, Nitrous Oxide, O₂/N₂, Heliox, O₂/CO₂.

Anesthetic Gases

Nitrous Oxide, Ethylene, Isoflurane.

Lab Gases

CO₂, Helium, Nitrogen, Carbon Monoxide (DLCO testing).

Therapy Gases

Medical Air, Oxygen, Heliox, O₂/CO₂, O₂/N₂.

CO₂ Characteristics

Colorless, odorless, 1.5× heavier than air, does not support combustion.

CO₂ Tank Color

Gray/Silver.

CO₂ Purity Requirement

FDA purity ≥ 99%.

Helium Characteristics

Very low density, odorless, tasteless, nonflammable, stable.

Helium Purity Requirement

FDA requires 99% purity.

Heliox Common Ratios

80/20, 70/30, 60/40.

Heliox Indications

Upper airway obstruction (croup, post‑extubation edema, epiglottitis), severe asthma, COPD exacerbation.

Why Heliox Works

Lower density improves airflow through narrowed passages.

Medical Air Characteristics

Colorless, odorless, density 1.29 g/L, filtered/purified atmospheric air.

Medical Air Purity Requirement

FDA purity 99%.

N₂O Characteristics

Colorless, sweet odor/taste, non‑flammable but supports combustion.

N₂O Uses

Analgesic, anxiolytic, anesthetic (dentistry, labor & delivery).

Oxygen Characteristics

Colorless, odorless, tasteless, transparent, nonflammable but supports combustion.

Oxygen Density

1.43 g/L (heavier than air).

Oxygen Purity Requirement

FDA purity ≥ 99%.

Nitric Oxide Characteristics

Colorless, toxic if overdosed, nonflammable but supports combustion.

Nitric Oxide Action

Potent vasodilator.

NO Indications

FDA‑approved for PPHN; used off‑label for adults.

DOT 3A Cylinder

Made from carbon steel.

DOT 3AA Cylinder

Heat‑treated steel alloy; stronger than 3A.

Meaning of “+” on Cylinder

Meaning of “*” on Cylinder*

Approved for 10‑year hydrostatic test interval.

Small Cylinder Connection Type

Yoke (PISS)

Large Cylinder Connection Type

Threaded valve (ASSS).

Oxygen

Green

CO2

Gray

Nitrous Oxide

Blue

Helium

Brown

Medical Air

Yellow

Heliox

Brown/Green

O2/CO2

Gray/Green

Service Pressure Definition

Pressure at 70°F when filled.

Full Tank Example

2000 psi + 10% = 2200 psi.

E‑Tank Conversion Factor

0.28

H‑Tank Conversion Factor

Why subtract 200 psi?

Safety buffer to avoid running out.

Minimum Capacity

≥ 13,000 cubic feet.

Liquid Oxygen Expansion Ratio

1 cu ft liquid = 860 cu ft gas.

Manifold System Definition

Multiple large cylinders grouped together at a fixed site.

Manifold Requirement

Must have backup system.

Working Pressure

Reduced to 50 psi.

Zone Valves Purpose

Shut off gas in case of leak or fire.

ASSS

Threaded, high‑pressure connections for large tanks.

DISS

Low‑pressure (<200 psi) threaded connectors with specific diameters.

PISS

Pin‑indexed system for small cylinders (AA–E).

Oxygen Pin Positions

2 & 5

Reducing Valve

Reduces gas pressure to usable level.

Flowmeter (Thorpe Tube)

Measures/regulates flow; range 0.25–15+ LPM.

Flow Restrictor

Fixed orifice delivering a specific flow at constant pressure.

Bourdon Gauge

Flowmeter used with adjustable high‑pressure regulator; reads flow based on pressure.

How to Clear Valve Outlet

Open and close valve quickly.

Never Use Oil Because…

Oil + oxygen = explosion risk.

How to Store Unsecured Tanks

Lay them on the floor.

Monitor PSI

Frequently check while in use.

Compression

Atmospheric air is compressed to high pressure

Cooling

Compressed air is cooled until it liquefies

Distillation

Nitrogen boils off first; oxygen remains as the heavier liquid

Collection

Purified liquid oxygen is stored and later vaporized for medical use