Storage and Delivery of Medical Gases

Comprehensive vocabulary flashcards covering medical gas characteristics, production methods, cylinder safety, and delivery equipment based on Egan's Chapter 41.

Medical Air

A therapeutic gas mixture containing $20.95\%$ ($21\%$) oxygen, represented by the color yellow, and is colorless, odorless, and tasteless.

Singultus

The medical term for hiccups, which can be managed using Carbon Dioxide ($CO_2$).

Heliox

A mixture of Helium and at least $20\%$ Oxygen used to decrease the work of breathing.

Nitric Oxide ($NO$)

An FDA-approved therapeutic gas for term and near-term infants with hypoxic respiratory failure; it has a slight metallic odor and must be mixed with oxygen.

Nitrous Oxide ($N_2O$)

Known as 'Laughing Gas,' this anesthetic gas has a slightly sweet odor and taste and is used in anesthesia.

Fractional Distillation

The most common and least expensive method for producing bulk oxygen by filtering, compressing, and cooling atmospheric air.

Joule Thompson effect

The process of heating (compression) and cooling (expansion) of air to remove pollutants during fractional distillation.

Physical Separation

A method used in smaller settings like homes involving molecular sieves or semipermeable membranes to produce oxygen concentrations.

Molecular Sieves

Devices composed of inorganic sodium aluminum silicate pellets that absorb nitrogen and water vapor to produce an oxygen mixture of more than $90\%$.

Oxygen Concentrators

Home-setting devices that use a vacuum to pull ambient air through a semipermeable membrane, producing an oxygen mixture of approximately $40\%$.

Department of Transportation (DOT)

The federal agency responsible for regulating gas cylinders and ensuring they meet all safety specifications.

3AA Cylinder

A cylinder classification made with steel alloy tempered for higher strength.

3A Cylinder

A cylinder classification for tanks made from carbon steel.

Plus sign ($+$)

A marking on a cylinder indicating it is approved for filling up to $10\%$ greater than its service pressure.

Asterisk ($*$)

A marking next to a test date indicating DOT approval for 10-year cylinder testing instead of the standard 5-year.

Frangible metal disk

A safety relief valve consisting of a thin metal disk that ruptures at a specific pressure.

Fusible plug

A safety relief valve made of metal alloy that melts at a certain temperature; commonly found on small cylinders.

Spring-loaded valve

A safety relief valve used on large cylinders that opens and vents gas when high pressure is reached.

Filling density

The ratio between the weight of liquid gas put into a cylinder and the weight of water the cylinder would contain if full.

Cylinder Factor for E tank

$$0.28$$

Cylinder Factor for G tank

$$2.41$$

Cylinder Factor for H and K tanks

$$3.14$$

Duration of Flow Formula (Gas)

$$\text{Duration of Flow} = \frac{\text{Pressure (psig)} \times \text{Cylinder factor}}{\text{Flow (L/min)}}$$

Duration of Liquid Flow Formula

$$\text{Duration of liquid gas} = \frac{\text{liquid } O_2 \text{ weight (lb.)} \times 344}{\text{Flow (L/min)}}$$

Working Pressure

The standard pressure of $50\,psig$ used to distribute gas through hospital piping systems.

American Standard Safety System (ASSS)

The safety system used for high-pressure connections on large gas cylinders (sizes F through H/K).

Pin-Index Safety System (PISS)

The safety system for small gas cylinders (sizes AA through E) utilizing specific hole positions to prevent accidental misconnections.

PISS Pin Positions for Oxygen

2 and 5

Diameter-Index Safety System (DISS)

A safety system designed to prevent the accidental interchange of low-pressure ($< 200\,psig$) medical gas connectors.

Reducing Valve

A device used to reduce high pressure from a cylinder to a lower, workable pressure.

Regulator

A device that controls both the pressure and the flow of a gas.

Bourdon gauge

A fixed-orifice, variable-pressure flowmeter that measures upstream pressure; it is the best choice for transport because it is not gravity-dependent.

Compensated Thorpe tube

A flowmeter that accounts for downstream resistance (back pressure) and provides accurate flow readings, but must be used in an upright position due to gravity.