A breathing apparatus (BA) provides a supply of breathable air when the surrounding atmosphere is compromised. These specialized devices are deployed in environments containing smoke, toxic gases, chemical vapors, or where oxygen levels are dangerously low. Understanding the proper operation of this equipment is directly related to safety and effectiveness during emergencies. Correct usage ensures the wearer receives a consistent, uncontaminated air supply, allowing them to work or escape a hazardous situation.
Defining Common Breathing Apparatus
The equipment designed to protect the respiratory system generally falls into two categories: air-purifying and air-supplying systems. Air-purifying respirators, often called filtering facepieces, filter contaminants from the existing air, but they are ineffective in oxygen-deficient atmospheres or against highly concentrated toxic gases. Air-supplying apparatus deliver clean air from an independent source, making them suitable for dangerous environments where the ambient air cannot sustain life.
The most common self-contained unit is the Self-Contained Breathing Apparatus (SCBA), which uses a compressed air cylinder worn on the user’s back. This cylinder stores air at extremely high pressure, often between 2,200 and 4,500 pounds per square inch (psi), depending on the cylinder material and capacity. A high-pressure regulator reduces this stored pressure in stages to a safe, breathable level before it reaches the face mask.
Another common type is the Supplied Air Respirator (SAR), which uses a long hose connected to a stationary air source located in a safe zone outside the hazardous area. This system offers a virtually unlimited air duration but restricts the wearer’s movement to the length of the airline. Both SCBA and SAR utilize a mask or hood assembly designed to create a complete seal around the face.
Essential Safety Checks Before Use
Before any breathing apparatus is deployed, a systematic inspection must be completed to confirm operational readiness.
Cylinder and Pressure Check
The air cylinder pressure gauge must be checked against the manufacturer’s minimum operating level. A fully charged cylinder typically registers between 2000 and 4500 psi. Any reading below a pre-determined safe threshold, often around 90% of full capacity, requires the cylinder to be replaced immediately.
Harness and Straps
The entire harness assembly and carrying straps require close examination for any signs of wear, cuts, or degraded material. The integrity of these components is important for maintaining the secure positioning of the heavy cylinder on the user’s back. All buckles and connection points must be tested to ensure they lock securely and adjust smoothly before the apparatus is donned.
Low-Pressure Warning Device
A specific test must be performed on the low-pressure warning device, which is an alarm designed to activate when the cylinder pressure drops to a pre-set limit. This alarm often sounds when approximately 25% of the air supply remains, providing the user time to exit the hazardous environment safely. The user must manually activate the air flow to trigger and verify the function of this alarm before committing to the environment.
Mask and Regulator
The face mask and regulator assembly must be checked for cracks, tears, or any compromise to the sealing surfaces. The connection point between the regulator and the mask must be secure and free of debris. The exhalation valve, which allows exhaled air to escape without compromising the seal, should also be clear. These checks ensure the apparatus will function as designed.
Donning and Operating the Device
The process of putting on and activating the breathing apparatus must be executed quickly and methodically. The harness should be slipped over the shoulders like a backpack, ensuring the weight is distributed evenly. All straps, including the waist belt and shoulder straps, must be cinched down tightly to prevent the unit from shifting during movement, which could compromise the face mask seal.
Once the harness is secure, the face mask is placed over the head, and the head straps are tightened systematically. The goal is to achieve an airtight seal. A proper seal verification, often called a negative pressure test, involves closing the intake valve and gently inhaling; the mask should pull tightly against the face and hold a vacuum for a moment.
The next action is connecting the regulator to the facepiece. This connection is typically a quick-connect fitting that locks into place with an audible click, ensuring a secure, leak-free junction. Once the regulator is attached, the main cylinder valve is opened fully by turning it counter-clockwise, which fully pressurizes the entire system.
Immediately after opening the main valve, the user should listen closely for any air leaks, which manifest as a distinct hiss. If no leaks are detected, the user can begin breathing normally, and the regulator will automatically supply air on demand. A final check involves monitoring the gauge to confirm the full air pressure is registered and that the needle does not drop rapidly, indicating a major leak.
During operation, the wearer must continuously monitor the air pressure gauge. Maintaining a calm and controlled breathing rhythm helps to conserve the air supply, as frantic breathing consumes air much faster. The duration of the air supply is determined by the cylinder size and the user’s exertion level. When the low-pressure alarm sounds, the wearer must immediately begin their exit strategy, recognizing they have a limited window of time remaining.
Cleaning and Storage Protocols
After the breathing apparatus has been removed, proper post-use protocol ensures its readiness for the next deployment. The facepiece must be thoroughly cleaned and sanitized to remove contaminants and biological residue. A mild soap or approved disinfectant solution is used to wash all surfaces of the mask, followed by a thorough rinse with clean water.
The regulator and hoses should be wiped down and closely inspected for any moisture ingress or physical damage. Any component showing signs of wear, such as cracked rubber or damaged connections, must be flagged for maintenance or replacement before the unit is returned to service. This inspection prevents failure during future emergency use.
If the air cylinder was used, it must be removed and sent for immediate recharging to its full operational pressure. Cylinders are hydrostatically tested periodically to maintain safety standards, and any cylinder due for testing should be noted. The entire apparatus is then reassembled, ensuring the newly charged cylinder is connected. The system must be stored in a cool, dry location where it is easily accessible and maintained in a ready-state condition.