TOPIC: SELF-CONTAINED BREATHING APPARATUS
LEVEL OF INSTRUCTION: COGNITIVE - APPLICATION
OBJECTIVES:
2-4.1. Identify the hazardous environments requiring the use of respiratory protection. (3-3.1a)
2-4.2. Identify the physical requirements of an SCBA user.(3-3.1a)
2-4.3. Identify the uses and limitations of SCBA. (3-3.1a)
2-4.4. Identify each component and safety feature of the SCBA.
(3-3.1a)
2-4.5. Identify the function of each component of the SCBA. (3-3.1a)
2-4.9. Identify the daily inspection procedures for the four main components of Self-Contained Breathing
Apparatus as illustrated in IFSTA Essentials:
2-4.11 Identify the uses of each major component of SCBA recharging systems as described in IFSTA
Essentials or department procedures. (3-5.3a)
2-4.18 Identify safety procedures to be used when wearing and working with self-contained breathing
apparatus, to include:(3-5.3a)
2-4.18.1
General safety considerations
2-4.18.2
Monitoring of firefighters entering hazardous situations.
2-4.18.3
Maintenance and storage operations.
2-4.19 Identify the functions of the human respiratory and circulatory systems, and the effects of stress
and toxic substances on them. (3-5.3a)
MATERIALS NEEDED: Any audio-visual materials necessary. SCBA unit complete, spare cylinder, air
cylinder refilling station.
REFERENCES: IFSTA Essentials, 4th Edition, pages 87-109
IFSTA Self-Contained Breathing Apparatus, 2nd Edition pages 7-12, 87-102, 199-215 and 257-270
PREPARATION (Step #1):
1
I.
Hazardous Environments
A.
Oxygen deficiency
1.
Combustion process consumes oxygen
2.
Production of toxic gases may displace oxygen
3.
Oxygen concentration diluted by other gases during combustion process
4.
Physiological effects of reduced oxygen (hypoxia)
a.
21% oxygen in air
1).
b.
c.
d.
17% oxygen in air
1).
Some muscular impairment
2).
Increase in respiratory rate
12%
oxygen in air
1).
Dizziness, headache, rapid fatigue
9% oxygen in air
1).
e.
Death in minutes from respiratory failure and concurrent heart
failure.
Elevated temperatures
1.
Heated air can damage respiratory tract
a.
b.
c.
C.
Unconsciousness
6% and less
1.)
B.
Normal
Excessive heat 120-130 degrees
1).
Blood pressure drop
2).
Circulatory failure
Inhalation of heated gases causes
1).
Pulmonary edema
2).
Death from asphyxiation
Respiratory tissue injury is not immediately reversible with the introduction
of fresh, cool air
Smoke
1.
Smoke is a suspension of fine particles of
a.
Tar
2
2.
D.
b.
Carbon
c.
Dust
Provides a means for the condensation of some of the gaseous products of
combustion
a.
Aldehydes
b.
Organic acids
3.
Some of these particles are lethal some are irritating
4.
Size of particle determines how deeply they will penetrate into the lung
Toxic gases
1.
2.
During fires a firefighter will be exposed to combinations of irritants and toxicants
a.
Each fire will present differing products of combustion
b.
Combinations may have a synergistic effect
Harmful effects of inhaled toxic gases
a.
b.
3.
4.
Disease of the lung tissue
Impair the oxygen carrying capacity of red blood cells
Type of toxic gases given off dependent upon
a.
Nature of the combustion
b.
Rate of heating
c.
Temperature of involved gases
d.
Oxygen concentration at time of combustion
Commonly found fire gases
a.
Carbon monoxide
1).
More fire deaths occur from exposure to carbon monoxide than any
other product of combustion
2).
Colorless
3).
Odorless
4).
Present at every fire
5).
Results from incomplete combustion
6).
Carbon monoxide combines with the bloods hemoglobin about 200
times more readily than oxygen causing oxygen to be excluded and
eventually hypoxia will result
3
7).
Concentrations of carbon monoxide above five hundredths of one
percent (0.05%) (500 ppm) can be dangerous
8).
Symptoms include
-Headache
-Dizziness
-Nausea
-Vomiting
-Cherry-red skin coloration
b.
9).
Administering pure oxygen is most important element in first aid
care
10).
Brain injuries may appear up to three weeks after a severe
exposure
Hydrogen chloride
1).
Colorless gas
2).
Pungent odor
3).
Causes swelling of upper respiratory tract
-Labored breathing
-Suffocation can result
4).
Due to the increased use of plastics, PVC is commonly found at
fires
-Polyvinyl chloride
5).
Overhaul stage is especially dangerous
-Latent heat can still decompose plastics
-Electrical cables may continue to decompose after fire is
extinguished
c.
Hydrogen cyanide (HCN)
1).
Interferes with respiration at the cellular and tissue level
2).
Classified as a chemical asphyxiate
3).
Colorless gas
4).
Noticeable almond odor
5).
Materials, which emit HCN, include
a.
Wool
4
6).
d.
e.
Nylon
c.
Polyurethane foam
d.
Rubber
e.
Paper
Concentrations above 270 PPM are almost immediately fatal
Carbon dioxide
1).
Nonflammable
2).
Colorless
3).
Odorless
4).
Concentrations of greater than 10 to 12 percent cause death within
a few minutes from paralysis of the brain's respiratory center
5).
Care should be when working around total CO2 flooding system
Nitrogen oxides
1).
2).
f.
b.
Two dangerous nitrogen oxides
a.
Nitrogen dioxide (NO2)
b.
Nitric oxide(NO)
Nitrogen dioxide is a pulmonary irritant
a.
Reddish brown in color
b.
Commonly called silo gas
c.
Released from pyroxylin plastics
3).
Causes pulmonary edema
4).
React with water and oxygen to form nitric and nitrous acids
5).
Cause arterial dilation, variation in blood pressure, dizziness, and
headaches
6).
Irritating effects can be tolerated while lethal dose is being inhaled
Phosgene (COCL2)
1).
Colorless, tasteless gas
2).
Disagreeable odor
3).
Produced when freon comes into contact with flame
4).
When it comes in contact with water, it decomposes into
hydrochloric acid
5
II.
Physical requirements
A.
B.
C.
Physical
1.
Sound physical condition
2.
Maximize amount of work that can be performed
3.
Maximize available air supply
Agility
1.
Must be agile as the unit will restrict wearers movements
2.
Will affect balance
Facial features
1.
D.
E.
III.
IV.
Need good facepiece seal
Medical
1.
Good motor coordination needed
2.
Must have good physical strength and size
3.
Good cardiovascular system
4.
Healthy respiratory system
Mental
1.
Adequate training in use of equipment
2.
Self-confidence
3.
Emotional stability
Limitations of the S.C.B.A.
A.
Limited visibility
B.
Decreased ability to communicate
C.
Increased weight
D.
Decreased mobility
Four basic components of open-circuit S.C.B.A.
A.
Backpack and harness assembly
1.
Designed to hold the air cylinder on the firefighter's back
2.
Adjustable harness straps provide a secure fit
3.
Waist strap is designed to properly distribute weight of cylinder or pack
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B.
Air cylinder assembly
1.
Many different sizes available
2.
Main weight of the breathing apparatus
3.
Cylinder pressures and capacities
a.
b.
Low pressure-2216 PSI, 45 cubic feet of air
1).
Rated to be 30 minute cylinder
2).
Expected use time 12 to 18 minutes
Low pressure-3000 PSI, 66 cubic feet of air
1).
c.
High pressure-4500 PSI, 45 cubic feet of air
1).
d.
Rated as a one hour cylinder
Regulator
1.
Regulator reduces the pressure from the cylinder to slightly above atmospheric
pressure and controls the flow to meet the needs of the wearer
2.
By-pass valve or purge valve is used as an emergency valve should the regulator
fail
3.
Pressure gauges are sometimes located on the regulator or in close proximity to
the facepiece
a.
4.
D.
Rated as a 30 minute cylinder
High pressure-4500 PSI, 88 or 90 cubic feet of air
1).
C.
Rated as a 45 minute cylinder
Should be within 100 PSI of the cylinder gauge
All units are required to have an audible quarter service alarm
Facepiece assembly
1.
Lens
2.
Exhalation valve
-One-way valve
V.
3.
Possibly a low pressure hose
4.
Adjustable straps or webbing
5.
Speaking diaphragm
Components of an Air Supply System
A.
Compressor
7
1.
Takes air and compresses it
2.
Operating principles
a.
b.
c.
B.
Air is cooled after each stage
1.
Removes some contaminants in the air
2.
Components
a.
Mechanical filter
b.
Dryer
c.
Air sweetener
d.
Carbon monoxide converter
Operating principles
a.
D.
Takes ambient air and compresses it in stages
Purification system
3.
C.
Usually electric driven motors
Air moves from the compressor to
1).
Permanent filtering systems
2).
Replaceable filtering systems
b.
Permanent systems remove large solid and liquid contaminants
c.
Replaceable systems remove
1).
Oil
2).
Water
3).
Odors
4).
Other gases and contaminants
Cascade (storage) system
1.
Three or more 300-cubic-foot cylinders
2.
Used for storage of compressed air
3.
Open cylinders one at a time during filling of SCBA bottles
Charging station
1.
Used to protect the operator should the cylinder rupture
2.
May or may not contain water depending on the type of cylinders being refilled
3.
Contains fragmentation deflector
8
4.
VI.
Emergency procedures
A.
B.
C.
VII.
May contain other control valves
Breathing from low-pressure hose
1.
Remove facepiece from hose
2.
Hold hose close to face
3.
Breathe directly from the hose
Breathing from the regulator
1.
Remove facepiece and low-pressure hose from the regulator
2.
Hold regulator close to face
3.
Breathe directly from the low-pressure hose connection on the regulator
Special breathing techniques (skip breathing)
1.
Inhale
2.
Hold breath as long as it takes to exhale and then inhale again before exhaling
3.
Take normal breaths and exhale slowly
Safety procedures
A.
General
1.
Use the provided SCBA in accordance with instructions and training
2.
Know the SCBA protection limits and safety features
3.
Know air supply duration
4.
Calculate a point of no return
5.
Ensure proper facepiece fit
6.
Follow basic safety guidelines
a.
Before entering a hazardous atmosphere, don and check the unit for
operation
b.
Always work in pairs
c.
Stay in contact with a wall, hoseline, lifeline/guideline or partner(s)
d.
Work to control breathing
e.
Be extremely cautious if forced to use the bypass valve
f.
Do not take the facepiece off
9
g.
B.
7.
Protect the SCBA from damage
8.
Inspect and maintain SCBA in accordance with department policy
Entry monitoring systems
1.
2.
C.
Report any malfunctions or apparent damage
Entry control
a.
Some type of device provided for each individual entering the area
b.
Entry time and location maintained
Guide line system
a.
A series of lines to which others entering the area attach
b.
An individual remains outside to monitor the line
c.
Entry time and location maintained
Maintenance and storage operations
1.
2.
3.
4.
Cleaning and sanitizing
a.
Follow department SOP's
b.
Clean and sanitize facepiece after each use
c.
Use cleansers recommend by the manufacturer
d.
Inventory of spare facepeices
Inspection and testing for defects
a.
For department SOP's
b.
Inspect all new units before placing in service
c.
Have breathing air quality tested quarterly
d.
Ensures all inspections are performed by qualified personnel
e.
Keep accurate records
f.
Remove defective facepieces from service
Repair and reconditioning
a.
Follow manufacturer procedures and recommendations
b.
Allow only personnel certified by the manufacturer to repair units
c.
Use exact replacement parts
Storage
a.
Follow department procedures
b.
Follow manufacturer's instructions for storage
10
5.
VIII.
IX.
c.
Ensure straps are in good condition and fully extended
d.
Store cylinders in cool dry well-ventilated area
e.
Be sure cylinders do not touch electrical sources
Recharging
a.
Avoid dropping or abusing air cylinders
b.
Be sure cylinders are secure before filling
c.
Never bang on valves with tools
d.
Be sure all connections are tight
e.
Close the cylinder valve and release air pressure in the regulator before
removing it from cylinder
Respiratory and Circulatory Systems
A.
Respiratory system - supplies the body with oxygen
B.
Circulatory system - transports oxygen to the cells of the body
C.
Effects of stress and toxic substances
1.
Increased levels of Carbon Dioxide
2.
Increased respirations
3.
Gases and toxins attack the oxygen exchange capability
Daily Inspection of SCBA
A.
Check to ensure that cylinder is ninety percent full
B.
Check all gauges for function
-Must be within 100 PSI of each other
C.
Check low pressure, quarter service alarm for function
D.
Check all hose connections
E.
Ensure that facepiece is clean and operational
F.
Check straps and harness
G.
Operate bypass and mainline valves
11