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This page is designed to give a basic understanding of the type of Self Contained Breathing Apparatus (SCBA) that German Township Fire Department uses. We currently utilize MSA air packs. SCBA's as according to National Fire Protection Association (NFPA) should operate using positive pressure. This is, air pressure that is supplied to the breathing mask should have higher pressure than the outside atmospheric pressure. The higher pressure makes it easier to breathe, and if the mask seal around the face begins to gap the positive pressure should keep outside gasses from entering the mask. Some SCBA's however are still equipped with negative pressure. You can think of this as in order to get air you have to pull the air from the regulator with your normal breathing. It is usually harder to breathe and if the mask gaps you will bring in outside smoke into the mask.
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Each air pack is equipped with a SCBA air cylinder. The air in the cylinder is normal breathing air (not just oxygen) which has been filtered. Pressure in these cylinders are
4500 psi. The 4500 air packs give about 25 to 35 minutes of air depending on the person. Each air pack screws into the air cylinder using a high pressure hose. The hose then runs into a regulator. The regulator then feeds air into the low pressure hose connected to the SCBA mask. The low air audible warnings usually begin to sound at 500 psi and quit sounding at 300 psi. This means at the start of the warning there is approximately 5 minutes of air left. MSA uses a bell to warn the firefighter of impending low air supply.
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 | Pictured is an MSA high pressure line hook up to cylinder. What is important here is the low air audible warning. The low air audible warnings usually begin to sound at 500 psi and quit sounding at 300 psi. This means at the start of the warning there is approximately 5 minutes of air left. MSA uses a bell to warn the firefighter of impending low air supply. |
 | Pictured is an MSA regulator. The regulator has a red and gold knob. The gold knob is used during normal operation. This is the gold knob allows air to flow through the regulator from the high pressure hose to the low pressure hose connected to the mask. The red knob on the other hand is known as the bypass. Opening the red knob allows air to flow around the regulator. This allows air directly from the bottle to enter the low pressure hose. This is used during emergency operations such as a failing regulator. |
The
black device on the SCBA belt is a personal alert system (PASS). This device
sounds an audible warning if it is not moved for a short period of time or is
manually activated by the firefighter. It is designed to alert others if the
person wearing it becomes unconscious or in trouble. Perhaps you remember the
haunting sounds of PASS going off on 9/11.
The German Township Fire Department would like to acknowledge the Boles Fire Protection District for their contribution of this article.
