Self-contained breathing apparatus

A self-contained breathing apparatus, or SCBA, is a respirator that does not clean the air. In place of cleaning the air, this respirator holds breathable air in a gas cylinder. It is often used by firefighters and workers doing a job in a confined space. In these places, cleaning the air can not be done, as people would die from not having oxygen to breathe. SCBAs in the United States are checked by NIOSH and the National Fire Protection Association. SCBAs also have rules under American National Standards Institute Z88.2. The newest is from 2015.

A person using a gas cylinder under water is using a SCUBA set. This is not an SCBA, which is used out of water.

 Types of SCBA 
NIOSH says there are three types of SCBA: closed-circuit, open-circuit, and continuous-flow.
 Closed-circuit type 
There are many names for the closed-circuit SCBA system. Some call it a rebreather, as no air leaves the SCBA system. There are two types of closed-circuit SCBA:
 Uses Compressed oxygen.
 Uses an oxygen-generating solid. This type of closed-circuit SCBA uses a chemical reaction. One has a chlorate candle has to be hit to start this type of closed-circuit SCBA. Another can use sodium hydroxide. 

Closed-circuit SCBAs work in the 1 hour range. But, ANSI Z88.2 also says that SCBAs can work from "15 minutes to 4 hours".

There are two types of closed-circuit SCBA: 
 Demand, where breathing causes the part of the SCBA that goes on the face to be pushed into the person's face.  
 Pressure-demand, where breathing causes the face part to be pushed away from the person's face.

 Open-circuit type 
In the open-circuit SCBA system, air leaves the SCBA system. As of 1987, compressed oxygen is not to be used. Like the closed-circuit type, there are demand and pressure-demand open-circuit SCBAs.

If the part that goes on the face was made for "demand," it cannot be used with a "pressure-demand" SCBA. And a part made for "pressure-demand" cannot be used with a "demand" SCBA. Both types of open-circuit SCBA work from 30 to 60 minutes.

As of 2015, Z88.2 says that most of these SCBAs use "Grade D" compressed air. But they can also use cryogenic air or compressed oxygen.

 Continuous flow 
Escape SCBAs are a type of continuous flow SCBA. Escape SCBAs come with hoods. Hoods are transparent plastic put on the head. Escape SCBAs are only used for getting out of a deadly place.

Escape SCBAs work from 3 to 10 minutes.

 Related pages 

 Respirator
 Gas mask
 NIOSH ratings

 Notes 

 References 




Category:Protective clothing
Category:Headgear
Category:Firefighting