Comprehensive Guide to SCBA Types, Components, and Safety Features

What are the two main types of SCBA?

Open-circuit SCBA and closed-circuit SCBA.

How does open-circuit SCBA operate?

Exhaled air is vented to the outside atmosphere.

How does closed-circuit SCBA operate?

Exhaled air remains within the system; carbon dioxide is removed, oxygen is added, and the reoxygenated air is recirculated to the facepiece.

Where are closed-circuit SCBA commonly used?

They are mainly used in shipboard operations, extended hazardous materials incidents, some rescue operations, and by industrial fire brigades.

What are the basic components of an open-circuit SCBA?

A backplate and harness assembly, air cylinder assembly, regulator assembly, and facepiece assembly.

What is the purpose of the backplate and harness assembly?

It holds the breathing air cylinder on the firefighter's back, stabilizes the unit, distributes weight, and provides a secure and comfortable fit.

What is the purpose of the air cylinder assembly?

It stores breathing air under pressure for the SCBA.

What materials may SCBA cylinders be constructed from?

Steel, aluminum, aluminum wrapped in fiberglass, or Kevlar/carbon composite materials.

What does the SCBA cylinder valve do?

It controls the flow of air from the cylinder into the SCBA system.

What information does the cylinder pressure gauge provide?

It indicates the amount of air remaining in the cylinder.

What is the purpose of the regulator assembly?

It reduces the high pressure of air from the cylinder to a pressure appropriate for breathing and controls airflow to the wearer.

What happens inside the regulator when the firefighter inhales?

A pressure differential occurs in the regulator, causing the diaphragm to move and allowing air to flow to the facepiece.

What happens when the firefighter exhales?

Exhalation moves the regulator diaphragm back to the closed position.

What is the bypass valve used for?

It allows air to flow directly from the cylinder to the regulator if the regulator fails.

What is the purpose of the SCBA facepiece?

It provides fresh breathing air while protecting the eyes and face from injury.

What are the main components of an SCBA facepiece?

Facepiece frame and lens, head harness, exhalation valve, nose cup, speaking diaphragm, and regulator fitting or hose connection.

What is the purpose of the facepiece frame and lens?

It protects the eyes and face and provides a sealed viewing area.

What is the purpose of the head harness?

It holds the facepiece securely against the face.

What does the exhalation valve do?

It releases exhaled air without allowing contaminated outside air into the facepiece.

What does the nose cup do?

It directs exhaled air away from the lens and helps reduce fogging or condensation.

What is the purpose of the speaking diaphragm?

It allows the firefighter to communicate while wearing the facepiece.

What is the purpose of the regulator fitting or hose connection?

It connects the regulator or hose to the facepiece and supplies breathing air.

What is a heads-up display (HUD)?

A system that provides information about SCBA operation, such as cylinder pressure, through lights or indicators visible to the firefighter.

What is the purpose of the SCBA low-pressure alarm?

It alerts the firefighter when the cylinder pressure has dropped to a predetermined level.

What is an end-of-service-time indicator (EOSTI)?

A warning system that alerts the firefighter when the SCBA cylinder is approaching the end of its usable air supply.

What is the Rapid Intervention Crew Universal Air Coupling (RIC UAC)?

A universal air connection that allows a rapid intervention crew to supply air to a firefighter's SCBA cylinder.

What is a buddy breathing system?

A system that allows firefighters to share air from one SCBA cylinder with another firefighter during an emergency.

What is an Emergency Escape Breathing Support System (EEBSS)?

A system that allows a firefighter to share air from one SCBA with another firefighter who needs emergency breathing support.

What is the purpose of an integrated PASS control module?

It provides information and controls for the PASS and SCBA, including displays or indicators for cylinder pressure, alarms, remaining battery life, and estimated operating time.

Why are alarm lights important on an SCBA?

They provide visual warnings and allow rescuers to recognize when a PASS device has activated, especially when noise may make the audible alarm difficult to hear.

What is a voice communications system used with SCBA?

A system that allows firefighters to communicate through the SCBA facepiece, sometimes using a wired or wireless connection to the firefighter's radio.

What are some limitations of SCBA equipment?

Limited visibility, decreased ability to communicate, decreased endurance, decreased mobility, possible poor condition of the apparatus, and limited air supply.