SCBA: Types, Usage, and Safety Tips for Firefighters

OBJECTIVES

Upon completion of this lesson, you will be able to:

• Describe the importance of Respiratory Protection.
• Elaborate the Respiratory Hazards of fire.
• Define respiratory equipment and its types.
• Describe the types of breathing apparatus.
• Elaborate the limitation of SCBA, physical and also psychological limitations.
• Describe the parts of SCBA.
• How to calculate the duration of air cylinder?
• Describe the methods of donning and demonstrate the donning doffing of SCBA

Introduction

Respiratory protection equipment is an essential component of the structural firefighting personal protection ensemble. A SCBA is both expensive and complicated; using one confidently requires practice. You must be proficient in using SCBA before you engage in interior fire suppression activities.

…………………………………………………………………………………….
…………………………………………………………………………………….

Respiratory Hazards

Firefighter need respiratory protection because a fire involves a complex series of chemical reactions that can rapidly affect the atmosphere in unpredictable ways. The most readily evident by-product of a fire is smoke. The visible smoke produced by a fire contains many different substances, some of which are dangerous if inhaled. As we know smoke includes toxic gases such as; Carbon monoxide (CO), Hydrogen cyanide & Phosgene, etc.

…………………………………………………………………………………….
…………………………………………………………………………………….

Conditions that Require Respiratory Protection

Most fire deaths are caused by smoke inhalation rather than burns. In fact, the products of combustion from house fires and commercial fires may be so toxic that just a few breaths can result in death—which is why you must always take respiratory protection before entering the fire. Use your SCBA at the fire scene and continue to wear it during overhaul until the air has been tested and proven to be safe by the safety officer.

…………………………………………………………………………………….
…………………………………………………………………………………….

Respiratory Equipment

The respirator is device that provides respiratory protection for the wearer. Breathing apparatus (BA) is a device worn by rescue workers, firefighters, and others to provide breathable air in an immediately dangerous to life or health (IDLH) atmosphere. Two basic types of respiratory equipment are Self Contained Breathing Apparatus and Non-Self-Contained Breathing Apparatus.

…………………………………………………………………………………….
…………………………………………………………………………………….

Self-Contained Breathing Apparatus (SCBA)

A respirator with an independent air supply that is used by firefighters to enter toxic or otherwise dangerous environment. It contains breathable compressed air. Also used by rescue workers while operating in areas of immediate danger to life and health, such as inside a building inferno or in a mine filled with smoke or toxic gas. Also called a compressed air breathing apparatus (CABA).

…………………………………………………………………………………….
…………………………………………………………………………………….

Types of SCBA

There are two main types of SCBA which are mentioned as under;

Open-circuit

SCBA in which the exhaled air is released into the atmosphere and is not reused. Typically used for structural firefighting. A tank of compressed air provides the breathing air supply for the user. Exhaled air is released into the atmosphere through a one-way valve.

Closed-circuit.

SCBA designed to recycle the user’s exhaled air. This system removes carbon dioxide and generates fresh oxygen. The air passes through a mechanism that adds oxygen within a closed system, where the oxygen is generated from a chemical canister. It is often used for extended operations such as mine rescue work and long tunnels.

Non Self-contained Breathing Apparatus (Supplied air Respirator)

An atmosphere-supplying respirator for which the source of breathing air is not designed to be carried by user. Uses an external source for breathing air. A hose line is connected to breathing air compressor or to a compressed air cylinder located outside the hazardous area. Commonly used in industrial setting, HAZMAT team and confined space entry team etc.

Uses and limitations for SCBA

• SCBA is designed to provide pure breathing air to fire fighter who are working in the hostile environment of fire.
• It must meet rigid manufacturing specifications so that it can functions in the increased temperature and smoke filled environments that fire fighters encounter.
• Limited amount of air available i.e. only for 30, 45 & 60 minutes’ Actual use time will depend on size of user, level of exertion, physical fitness, and conditions of use.
• An SCBA cylinder will generally havea  realistic useful life of not more than 50% of the rated time. (i.e. SCBA cylinder rated for 30 min. can be expected to last for a maximum of 15 min. during strenuous firefighting)

…………………………………………………………………………………….
…………………………………………………………………………………….

Factors to Manage Air Supply

To properly manage the air supply, a firefighter must consider the following factors;

• The time and the effort it will take to reach the task destination. Climbing stairs will take more energy and air than walking across a flat floor.
• The amount of air that will be available upon reaching the task destination.
• The amount of time necessary to complete the task and the air that will be used during that period.
• Some tasks will take more energy and air.
• The amount of time it will take to reach a safe area.
• At the end of this time, the firefighter must have a reserve of air for unexpected emergencies.

Note: SCBA provides a very limited window of time for firefighting and safe exit from the hazardous conditions of the fire. It is essential that you have a margin of safety built into your air supply for the unexpected emergencies.

Physical Limitations of the User

• Conditioning is important for SCBA users. An out-of-shape firefighter will consume the air supply more quickly and will have to exit the fire building long before a well-conditioned firefighter does so.
• Overweight or poorly conditioned firefighters are also at greater risk for heart attack due to physical stress. Altogether, the protective clothing and SCBA that must be worn when fighting fires weight more than 50 pounds.
• Moving with this extra weight requires additional energy, which in turn increases air consumption and body temperature.
• Taken collectively, this activity places additional stress on a firefighter’s body.
• A person with ideal body weight and its good physical condition will be able to perform more work per cylinder of air than a person who’s overweight or out of shape.

Psychological Limitations of the Users

• The user must make mental adjustments when wearing an SCBA. Breathing through SCBA is different from normal breathing and can be very stressful.
• Covering your face with a face piece, hearing the air rushing in, hearing valves open and close, and exhaling against positive pressure are all foreign sensations.
• The surrounding environment, which is often dark and filled with smoke, is foreign as well.
• Firefighters must adjust so they can operate effectively under these stressful conditions.
• Covering your face with a face piece, hearing the air rushing in, hearing valves open and close, and exhaling against positive pressure are all foreign sensations.
• The surrounding environment, which is often dark and filled with smoke, is foreign as well.
• Firefighters must adjust so they can operate effectively under these stressful conditions.
• Practice in donning PPE, breathing through SCBA, and performing firefighting tasks in darkness helps to build confidence.
• Training generally introduces one skill at a time. As your skill improves, you will be able to tackle tasks characterized by increasing levels of difficulty.

…………………………………………………………………………………….
…………………………………………………………………………………….

Parts of SCBA

There are three main parts of a SCBA which are;

1. Air Cylinder.
2. SCBA Harness.
3. Face Piece.

Parts Description of SCBA

Air cylinder: 

The component of SCBA that stores compressed air supply. Additionally, a main valve is used to control the air supply towards the assembly head.

Specification of Air Cylinder:
Material: Carbon Composite
Liquid volume: 9 liter
Working pressure: 300 bar
Testing pressure: 450 bar

Calculations of Cylinder Duration
If the pressure gauge is showing below or equal to 200 bar:
Duration = Pressure x Volume / 40

If the pressure gauge is showing above 200 bar:
Duration = Pressure x Volume / 44

Hydrostatic testing
Hydrostatic testing is pressure testing to verify the strength of cylinders against unwanted rupture. Cylinders must be tested after every 5 years. For the filling of cylinders, we used a compressor. A compressor is a device for increasing the pressure and density of gas.

…………………………………………………………………………………….
…………………………………………………………………………………….

SCBA Harness
part of SCBA which allows fire fighters to wear it as a “backpack”.

Other parts of Harness:

1. Backpack:
   The harness of the SCBA supports the components worn by a firefighter.
2. SCBA Regulator:
   This part reduces the high pressure in the cylinder to a useable lower pressure and controls the flow of air to the user.

…………………………………………………………………………………….
…………………………………………………………………………………….

Dual path pressure reducer

A feature that automatically provides a backup method for air to be supplied to the regulator of an SCBA if the primary passage malfunctions.

Airline

The hose through which air flows, either within an SCBA or from an outside source to a supplied air respirator.

End of service time indicator

A warning device on SCBA that alerts the user that the end of the breathing air is approaching.

Pressure gauge 

A device that measures and displays pressure readings. In an SCBA the pressure gauge indicates the quantity of breathing air that is available at any time.

• Lungs Demand valve (LDV).
• Low-pressure hose
• High-pressure hose
• Warning whistle.
• Hand Wheel (Connector)
• Cam lock

…………………………………………………………………………………….
…………………………………………………………………………………….

Face Piece Assembly

It delivers breathing air to the firefighter and protects the face from high temperatures and smoke. It consists of;

• Straps; (Head, Temporal, Neck, and Carrying)
• Exhalation valve, protective cap
• Nose cup, inhalation valve
• LDV port and LDV release button
• Visor, inner face cavity
• Material ofthe mask is EPDM. (ethylene propylene diene monomer rubber)

…………………………………………………………………………………….
…………………………………………………………………………………….

Methods of Donning and Doffing SCBA

Don means to put on an item of clothing or equipment while Doff means to take off an item of clothing or equipment. There are two methods of donning a SCBA;

• Overhead method.
• Coat method.

…………………………………………………………………………………….
…………………………………………………………………………………….

Donning SCBA Using the Over-the-Head Method (Skill Drill)

1. Open the case and lay out SCBA with cylinder valve away from self and place shoulder straps out to the sides.
2. Fully open the main cylinder valve.
3. Bend down and grasp the SCBA back plate with both hands. Use legs to lift SCBA overhead. Rotate SCBA 180 degrees so waist straps are pointed toward the ground.
4. Slowly slide pack down back while sliding arms into shoulder straps. Tighten shoulder straps and secure waist straps.
5. Don face piece and check for adequate seal. Pull the hood into position, don the helmet, and secure chin strap.
6. If necessary, connect the regulator to face piece. Activate air flow and PASS alarm (If available).

Doffing of SCBA (Skill Drill)

1. Remove gloves. Remove the regulator from face piece or disconnect the low-pressure hose from regulator.
2. Shut off air-supply valve to stop the flow of air and remove helmet and pull the protective hood down around neck.
3. Loosen straps on face piece remove face piece and release the waist belt.
4. Loosen the shoulder straps and remove SCBA and shut off the aircylinder valve.
5. Bleed air pressure from the regulator by opening the purge valve.
6. Turn off integrated PASS device, if present and place SCBA in a safe location