Fires need oxygen to survive… and so do firefighters
The first use in the UK of breathing equipment was in 1800 with the Smoke Helmet. It worked along the same principle as deep-sea divers at the time by using a long hose connected to a helmet. These were heavily restricted by the length of the hose attached.
Next came ‘The Proto’. Originally designed for use in mines, the system was entirely self-contained. Oxygen was stored in a cylinder at the back along with an absorbent in a bag at the front. Air exhaled was passed into the bag which absorbed the carbon dioxide and was mixed with fresh oxygen.
These were evolved until the late 1950s.
Compress to impress
The 1960s brought about a new type of breathing apparatus which used compressed air, instead of cleaning air that had been exhaled. The kit used a full face mask which allowed for more communication between crew members.
The equipment acted as heat and flame resistance, as well as activating a distress signal if movement was not sensed for a certain period of time. This distress signal allowed firefighters to locate their partners and the signal could also be activated manually.
Self Contained Breathing Apparatus systems
Open circuit systems are similar to sets of scuba equipment as they contain filtered, compressed air to be inhaled through the mask. They contain two regulators. The first reduces the pressure of the airflow to the mask. The second reduces it even further to a level just above or below standard atmospheric pressure (judged to be 101,325 Pascals). The air filter has three standard sizes, 4 litres, 6 litres and 6.8 litres.
Closed-circuit systems are typically smaller as they filter and recirculate gas emitted. They are usually used when a longer supply of oxygen is required or if open circuit systems are too big, for example in mine rescue operations because open circuit tanks cannot fit through restricted spaces.
The Open Circuit system has two types of fail-safes, a negative pressure operation and a positive pressure operation.
Negative pressure relies on the pressure inside the mask to be slightly lower (hence negative) than that of ambient pressure. As such if the mask is not sealed perfectly, surrounding gases will be pulled into the mask due to the pressure difference.
Positive pressure relies on pressure in the mask being sufficiently higher than the surroundings to activate the airflow. If the mask falls off or air begins to leak the valves will release more air into the mask in order to try and keep the pressure stable. So if the mask comes off completely the airflow will increase massively and wasted oxygen will be excessive.
Not just for firefighters
SCBAs (Self Contained Breathing Apparatus) are used beyond just firefighting. Firefighting equipment has an obvious reliance on heat and flame resistance, while industry use is centred around petrochemical and nuclear operations. More recently the equipment has been used by medical staff treating Ebola cases.
Realism for Flashing Lights
SCBA equipment arrives in the newest Flashing Lights update, increasing your firefighting arsenal. Flashing Lights is available on Steam now.
Article written by Will Stallibrass