Chapter 41: Storage and Delivery of Medical Gases

What is the FDA purity standard for O2?

99.0%

Air

AIR Supports Combustion Yellow

Bordon Gauge

Advantages: Operates under variable pressures as adjusted with the pressure reducing valve; isn't affected by gravity. Disadvantage: Inaccuracy when pressure distal to the orifice changes, specifically if downstream pressure increases the pressure difference across the orifice and actual output flow decrease.

Thorpe Tube

Advantages: Pressure compensated or uncompensated (rare) Disadvantages: Gravity. Not ideal for transport

Advantages vs Disadvantages of a flow restrictor

Advantages: low cost, simple, reliable (no moving parts), cannot be set to incorrect flow, and can be used in any position (gravity independent). Disadvantages: different versions required for different flows, accuracy varies with changes in source and downstream pressures , and cannot be used with high-resistance equipment.

Carbon Dioxide

CO2 Nonflammable Gray

What is CGA?

Compressed Gas Association * this is why safety guidelines are divided into cylinder storage, transport, and use.

What is DOT?

DOT- Department of Transportation *there are specific requirements for shipping biohazard materials according to the Hazardous Materials Standard. *DOT is classified into two categories: 3A cylinders made from carbon steel, and 3AA containers are made for higher strength with aluminum.

What does it mean to be hydrostatically?

Expansion which occurs when the bottle is pressurized to maximum test pressure during the qualification test. * An approved cylinder with a service pressure of 2015 psi can be filled to 2200 psi. This type of testing means the cylinder is looked over for leakage, expansion, and wall stress. This occurs every 5-10 years.

Helium/Oxygen (Heliox)

He/02 Supports Combustion Brown/Green

What are therapeutic effects of Heliox and NO?

Heliox (mixture of O2 and He) may be used to manage severe cases of airway obstruction. Nitric Oxide in treatment of term or near term infants for hypoxemic respiratory failure. Also, could be used for adults.

Amount of gas in a cylinder

amount of gas in cylinder= liquid weight (lb) X 860 2.5 lb/L

Duration of Flow equation

duration of flow (min)= pressure (psig) X cylinder factor Flow L/M

Duration of gas (min)

duration of gas (min)= amount of gas in cylinder (L) Flow (L/min)

Helium

Не Nonflammable Brown

What is the cylinder size for an H and K tank?

3.14

What is standard working pressure?

50 psi

What is the difference between a regulator, reducing valve, and flow meter?

*A regulator is an adjustable reducing valve commonly used in combinations with a Bourdon-type flow gauge. The combination of a flow meter with a reducing valve is called a regulator. *Reducing valve is used for reduction in gas valve. *Flow meter is for control of gas flow to a PT.

What are the symbols stamped on the tank shoulder? What do they indicate?

*An asterisk (**) next to the test date indicates DOT approval for 10-year testing. *A plus sign (+) means that the cylinder is approved for filling to 10% greater than its service pressure.

What is the cylinder size for a E tank?

0.28

Oxygen

02 Supports Combustion Green

What is the difference between a compensated and an uncompensated Thorpe tube?

An uncompensated Thorpe tube is calibrated in L/min. Gas is controlled by the needle valve before the flow tube. Restriction could cause resistance and falsely shows a flow lower than actually delivered to the patient. This equals inaccuracy. **Location of the needle is before the flow tube. A compensated Thorpe tube is used when a more accurate gas flow is needed. This Thorpe tube has a high resistance, this works great with high-resistance equipment. Gravity dependent (not ideal for patient transport). **Location of needle valve is after the flow tube.

Nitrogen

N Nonflammable Black

Nitrous Oxide

N20 Supports Combustion Blue

Nitric oxide

NO Supports Combustion Light Blue

What is NFPA?

National Fire Protection Agency. * this is why safety guidelines are divided into cylinder storage, transport, and use. *Established in 1896, devoted to eliminating death, injury, property and economic loss due to fire, electrical and related hazards.

How is liquid O2 stored?

O2 can be stored in a high-pressure metal cylinder or a cryogenic (low temp) cylinder.

What is the difference between the 3 safety systems?

PISS: is part of the ASSS but applies only to the valve outlets of small cylinder up to and including size E. *Prevents misconnections, like ASSS. ASSS: standards for high-pressure connections between large gas cylinders (sizes F through H/K) and their attachments. * makes misconnections difficult because the size (bore) of the cylinder outlet and its threading differ based on the type of gas in the cylinder. DISS is established to prevent accidental interchange of low pressure (<200 psi) medical gas connectors.

Where is the pin location for O2?

Pin position of 2 and 5

Small vs Large cylinders

Small cylinders are labeled E-AA, used for transport, and anesthetic. * have post valve and yoke connector. Large cylinders are labeled F-H, and K. *Have a threaded valve outlet.

How is O2 produced?

Small quantities- physical separation of O2 from air. Large quantities- produced by by fractional distillation and atmospheric air. Fractional Distillation: most common and least expensive method for producing O2. First atmospheric air is filtered to remove pollutants, water, and CO2. The purified air is liquefied by compression and cooled by rapid expansion (Joule - Thompson effect). The resulting mixture of liquid O2 and nitrogen is heated slowly, then nitrogen with its boiling point escapes and the remaining O2 is transferred to cryogenic cylinders.

How do we determine the contents of a gas vs liquid cylinder?

To know how much gas is contained in a cylinder, you need to measure the pressure. EX. If a cylinder is full at 2200 psi, it will be half full when the pressure decreases to 1100 psi. In a liquid cylinder the measured pressure is vapor pressure above the liquid. Weighing the cylinder is the only accurate method for determining the contents.

What is the purpose of cracking a cylinder?

To make sure there is no dust, dirt, or debris.

What is the purpose of a pressure relief valve?

To prevent a cylinder from rupturing or possibly exploding the cylinder. *If there was an increase in gas temperature, that would increase the gas pressure. This high pressure would cause said explosion.