Chapter 41

Question 1

What are the three safety relief valves?

Answer 1

Frangible Metal Disc: ruptures at a specific pressure

Fusible Plug : melts at a specific temperature

Spring-Loaded valve : opens and vents gas at a set high pressure

Question 2

Color Codes for Medical Gas Cylinders

Answer 2

Oxygen - green
Carbon dioxide - gray
Nitrous oxide- light blue
Cyclopropane - orange
Helium - brown
Carbon dioxide & Oxygen- gray and green
Helium and oxygen - brown and green
Air - yellow

Question 3

How do you measure a gas filled cylinder?

Answer 3

Gas filled cylinders have a psi of 2200 and the formula to measure their duration is

Duration of flow = Psig x cylinder factor / Flow ( L/min )

Question 4

What is the cylinder factor for H/K and E cylinders ?

Answer 4

H/K : 3.14

E : 0.28

Question 5

What are the two organizations that are associated with Gas Cylinder Safety?

Answer 5

(NFPA). National Fire Protection Agency

(CGA). Compressed gas association

Question 6

How do you measure liquid gas cylinders?

Answer 6

They are measured by how much the cylinder weighs

1 liter of liquid gas weighs 2.5 pounds
It generates a pressure of 860 psig

The formula for liquid gas is

Amount of gas in cylinder = liquid weigh (lb) x 860 / 2.5 lb/ L

Question 7

Physical Separation

Answer 7

There are two types of methods to separate O2 from air

1. Molecular Sieves : composed of inorganic sodium aluminum silicate pellets. The pellets absorb N2 gases and water vapor from the air providing a concentrated mixture of more than 90% of O2 for patient use.
2. Oxygen concentrator : devices that are used primarily for supplying low- flow O2 in the home care setting. It sucks in the O2 and water vapor faster than the N2 (nitrogen). This system can produce a O2 mixture of approximately 40%

Question 8

Fictional Distillation

Answer 8

Is the most common and least expensive method for producing CO2. The steps are listed below
1. Atmospheric air is filtered to remove pollutants, water, and carbon dioxide
2. The purified air is liquified by compression and cooled by rapid expansion
3. O2 and nitrogen are heated slowly in distillation towers
4. N2 with a boiling point of 195 .8 degrees escapes first followed by argon, krypton, and xenon
5. O2 remaining is transferred to specially insulated cryogenic storage cylinders

Question 9

Cylinder Labeling and Identification

Answer 9

1. The letters DOT or ICC followed by the cylinder classification ( 3A or 3AA )
2. The normal filling pressure (psig)
3. The letter size of the cylinder ( E,G, H, ETC )
4. Followed by the cylinder serial number
5. The third line provides a mark of ownership followed by the manufactures stamp
6. Dates of test ( every 5-10 years )

An * next to the date indicates DOT approval for 10 year testing
An + means that the cylinder is approved for filling to 10% greater than its surface pressure

Saftey test are conducted every 5-10 years
Cylinders are pressurized to 5/3 of their service pressure

Question 10

Department of Transportation

Answer 10

DOT

DOT type 3A cylinders are made from carbon steel
DOT type 3AA containers are manufactured with a steel alloy tempered for higher strength

They are both made from seamless steel

Question 11

Safety indexed connector systems

Answer 11

3 systems used to ensure correct gas source

1. American Standard Safety System ( ASSS)
   - for the large cylinders and their attachments ( Cylinder H/K )
2. Pin- Index Safety System (PISS)
   - for small cylinders up to and including cylinder E.
3. Diameter -Index Pressure safety System (DISS)
   - for low - pressure gas connectors

2-5 for oxygen
1-5 for air

Question 12

Flow Meters and the different types

Answer 12

There are three categories of flow meters that are used in respiratory care

Flow meters allow the rate of gas flow to a patient to be set and controlled.

1. Flow Restrictor : is the simplest and least expensive of the flow meters. It consists of fixed orifice calibrated to deliver a specific flow at a constant pressure of 50 psig.
2. Bourdon gauge : a type of flowmeter that is used combined with a pressure- reducing valves. It also uses a fixed orifice similar to the flow restrictor. IT operates under variable pressure as adjusted with the pressure- reducing valve. Increasing the upstream pressure increases gas flow out of the device unless downstream pressure also increases.
3. Thorpe Tube : is always attached to a 50 psig source. It’s used to measure flow. Functions as a variable - orifice at constant pressure flow meter.

• compensated : prevents change in downstream resistance or back pressure from affecting meter accuracy.
• uncompensated : gas from 50 psig source flows into the metro at a rate controlled by a needle valve located before the flow tube.

Question 13

Cylinder Storage

Answer 13

Again follows the recommendations of the NFPA and CGA

Steps for storage

1. Store in racks or chained to the wall.
2. Store full and empty cylinders separately
3. Keep away from combustible material ( no heat)
4. Keep the temperature less than 125 degree Fahrenheit
   Keep cap on if not in use

Question 14

The Proper way to transfer Cylinders

Answer 14

There are five steps on transporting cylinders
1. Use the cylinder cart
2. Keep protective cap in place
3. Protect cylinders from striking other cylinders and other objects
4. Avoid dragging and dropping
5. Always read labels before use and transport

Question 15

What are the advantages and disadvantages of Flow Restrictors?

Answer 15

Advantages
- low cost , simple, and reliable
- cannot be set to incorrect flow
- can be used in any position ( gravity independent)

Disadvantages
- different versions require different flows
- accuracy varies with changes in source and downstream pressures
- cannot be used with high resistance equipment

Question 16

What are the three factors effecting duration of flow?

Answer 16

1. Gas Flow
2. Cylinder size
3. Cylinder pressure

Question 17

What does a hygrometer measure?

Answer 17

It measures humidity

Question 18

Integrated oxygen cylinders

Answer 18

( grab and go)
It eliminates the need for separate oxygen tanks, bourdon gauges regulators, and oxygen key/ wrenches

Question 19

What is the working pressure?

Answer 19

50 psig

Question 20

Air

Answer 20

Colorless, orderless, naturally occurring gas mixture
Contains 20.95% of oxygen, 78% nitrogen and about 1% trace gas

Question 21

Carbon Dioxide

Answer 21

Colorless and orderless
Gravity of 1.52 and is heavier than air

Question 22

Helium ( He)

Answer 22

Has a density of 0.1785 g/l
Heliox ( mixture of helium and oxygen ) most always be mixed with at least 20% oxygen
Manages sever cases of airway obstruction

Flows easier

Question 23

Nitric Oxide (No)

Answer 23

Selective pulmonary dilator
Exposure to high concentrators alone can cause methemoglobinemia which can cause hypoxia

FDA approved to treat near term infants with hypoxic respiratory failure

Question 24

Nitrous Oxide (N2O)

Answer 24

Must always be mixed with oxygen
Produced by thermal decomposition of ammonium nitrate

Question 25

Characteristics of Oxygen

Answer 25

- nonflammable but greatly accelerates combustion - colorless, orderless, transparent, and tasteless - at standard temperature, pressure, and its dry - at room temperature and 1 atm pressure only 3.3 ml of O2 dissolves in 100 ml of water

Question 26

Bulk Oxygen system

Answer 26

- Used to meet large O2 needs of health care facilities - Less expensive in the long run - Systems hold at least 20,000 cubic feet of gas - oxygen may be stored in liquid form - a key standard of the bulk O2 system is the requirement for a reserve or back up gas supply to equal the average daily gas use in the hospital - to meet that requirement larger facilities have a second, smaller liquid tank. - smaller facilities may use cylinder gas manifold as the backup. - failure of a bulk O2 supply can be life threatening to any patient receiving O2 or gas- powered ventilation support.

Question 27

Gas Supply Systems

Answer 27

There are three types of centrally located gas supply systems 1. Alternating supply of cylinder manifold system : consists of large cylinders (H/K) of compressed O2 banked together in series 2. Cylinder supply systems with reserve supply : consist of a primary supply, a secondary supply and a reserve supply. 3. Bulk gas system with reserve

Question 28

The different types of Medical gases

Answer 28

1. Laboratory gas : used for equipment calibration and diagnostic testing. Helium, Nitrogen, hydrogen helium to manage severe cases of airway obstruction. It’s low density decreases the work of breathing by making gas flow more laminar. 2.Anesthetic Gas- combined with oxygen to provide anesthesia during surgery. Nitrous oxide depresses the nervous system. If not combined with oxygen it can cause long lasting damage. 3. Therapeutic gas : used to relieve symptoms and improve the oxygenation of patients with hypoxemia.

Question 29

How to use oxygen cylinders properly

Answer 29

First step verify that the cylinder is properly labeled Verify that the cylinder has sufficient O2 in order to be used Use the cart with a chain or a hotline rack to secure the cylinder during transportation Avoid anything flammable or any sources of heat Make sure the connectors correspond with the cylinders Post a no smoking sign “Crack” the cylinder to remove debris